C/C++ Interactive Guide/c-cplusplus-interactive-guide.iso/c_ref/csource4/232_01/apndx1

Text File | 1987-06-17 | 53.5 KB | 1,450 lines

.so macros
.nh
.ds CF
.ds CH
.ps +0.2i
.nr PO +0.2i
.Nm Object
.PP
The class \fBObject\fP is a superclass of all classes in the system, and is
used to provide a consistent basic functionality and default behavior.
Many methods in class \fBObject\fP are overridden in subclasses.
.SH
Responds to
.Rs ==
Return true if receiver and argument are the
same object, false otherwise.
.Rs ~~
Inverse of ==.
.Rs asString
Return a string representation of the receiver,
by default this is the same as \fIprintString\fP, although one or the
other is redefined in many subclasses.
.Rs asSymbol
Return a symbol representing the receiver.
.Rs class
Return object representing the class of the receiver.
.Rs copy
Return shallowCopy of receiver.
Many subclasses redefine shallowCopy.
.Rs deepCopy
Return the receiver.  This method is redefined in many sub\%classes.
.Rs do: d
The argument must be a one argument block.
Execute the block on every element of the receiver collection.
Elements in the receiver collection are listed using \fIfirst\fP and \fInext\fP
(below), so the default behavior is merely to execute the block using the
receiver as argument.
.Rs error:
Argument must be a String.  Print argument string as error message.
Return \fBnil\fP.
.Rs first n
Return first item in sequence, which is by default simply the receiver.
See \fInext\fP, below.
.Rs isKindOf:
Argument must be a \fBClass\fP.  Return true if class of receiver, or any
superclass thereof, is the same as argument.
.Rs isMemberOf:
Argument must be a \fBClass\fP.  Return true if receiver is instance of
argument class.
.Rs isNil
Test whether receiver is object \fBnil\fP.
.Rs next n
Return next item in sequence, which is by default \fBnil\fP.  This message is
redefined in classes which represent sequences, such as \fBArray\fP
or \fBDictionary\fP.
.Rs notNil
Test if receiver is not object \fBnil\fP.
.Rs print
Display print image of receiver on the standard output.
.Rs printString
Return a string representation of receiver.
Objects which do not redefine printString, and which therefore do not have
a printable representation, return their class name as a string.
.Rs respondsTo:
Argument must be a symbol.  Return true if receiver will respond to
the indicated message.
.Rs shallowCopy
Return the receiver.  This method is redefined in many sub\%classes.
.Ex
7 ~~ 7.0    True
7 asSymbol    #7
7 class    Integer
7 copy    7
7 isKindOf: Number    True
7 isMemberOf: Number    False
7 isNil    False
7 respondsTo: #+    True
.Nm Object UndefinedObject
.PP
The pseudo variable \fBnil\fP is an instance (usually the only instance) of the
class \fBUndefinedObject\fP.  \fBnil\fP is used to represent undefined values,
and is
also typically returned in error situations.  \fBnil\fP is also used as a terminator
in sequences, as for example in response to the message \fInext\fP when there are
no further elements in a sequence.
.SH
Responds to
.Rs isNil r
Overrides method found in Object.  Return true.
.Rs notNil r
Overrides method found in Object.  Return false.
.Rs printString r
Return 'nil'.
.Ex
nil isNil    True
.Nm Object Symbol
.PP
Instances of the class \fBSymbol\fP are created either by their literal
representation, which is a pound sign followed by a string of nonspace
characters (for example #aSymbol ),
or by the message \fIasSymbol\fP being passed to an object.
Symbols cannot be created using \fInew\fP.  Symbols are guaranteed to have
unique representations; that is, two symbols representing the same
characters will always test equal to each other.  Inside of literal
arrays, the leading pound signs on symbols can be eliminated, for example:
#(these are symbols).
.SH
Responds to
.Rs == r
Return true if the two symbols represent the same characters,
false otherwise.
.Rs asString r
Return a String representation of the symbol without the leading pound
sign.
.Rs printString r
Return a String representation of the symbol, including the leading pound
sign.
.Ex
#abc == #abc    True
#abc == #ABC    False
#abc ~~ #ABC    True
#abc printString    #abc
\&'abc' asSymbol    #abc
.Nm Object Boolean
.PP
The class \fBBoolean\fP provides protocol for manipulating true and false values.
The pseudo variables \fBtrue\fP and \fBfalse\fP are instances of the subclasses of
\fBBoolean\fP; \fBTrue\fP and \fBFalse\fP, respectively.
The subclasses \fBTrue\fP and \fBFalse\fP, in combination with blocks, are used to
implement conditional control structures.  Note, however, that the
bytecodes may optimize conditional tests by generating
code in-line, rather than using message passing.
Note that bit-wise boolean operations are provided by class \fBInteger\fP.
.SH
Responds To
.Rs &
The argument must be a boolean.  Return the logical conjunction (and)
of the two values.
.Rs |
The argument must be a boolean.  Return the logical disjunction (or)
of the two values.
.Rs and:
The argument must be a block.  Return the logical conjunction (and)
of the two values.  If the receiver is false the second argument is not
used, otherwise the result is the value yielded in evaluating the argument
block.
.Rs or:
The argument must be a block.  Return the logical disjunction (or)
of the two values.  If the receiver is true the second argument is not
used, otherwise the result is the value yielded in evaluating the argument
block.
.Rs eqv:
The argument must be a boolean.  Return the logical equivalence (eqv)
of the two values.
.Rs xor:
The argument must be a boolean.  Return the logical exclusive or (xor)
of the two values.
.Ex
(1 > 3) & (2 < 4)    False
(1 > 3) | (2 < 4)    True
(1 > 3) and: [2 < 4]    False
.Nm Object Boolean True
.PP
The pseudo variable \fBtrue\fP is an instance (usually the only instance) of
the class \fBTrue\fP.
.SH
Responds To
.Rs ifTrue:
Return the result of evaluating the argument block.
.Rs ifFalse:
Return \fBnil\fP.
.Rs ifTrue:ifFalse:
Return the result of evaluating the first argument block.
.Rs ifFalse:ifTrue:
Return the result of evaluating the second argument block.
.Rs not
Return \fBfalse\fP.
.Ex
(3 < 5) not    False
(3 < 5) ifTrue: [17]    17
.Nm Object Boolean False
.PP
The pseudo variable \fBfalse\fP is an instance (usually the only instance) of
the class \fBFalse\fP.
.Rs ifTrue:
Return \fBnil\fP.
.Rs ifFalse:
Return the result of evaluating the argument block.
.Rs ifTrue:ifFalse:
Return the result of evaluating the second argument block.
.Rs ifFalse:ifTrue:
Return the result of evaluating the first argument block.
.Rs not
Return \fBtrue\fP.
.Ex
(1 < 3) ifTrue: [17]    17
(1 < 3) ifFalse: [17]    nil
.Nm Object Magnitude
.PP
The class \fBMagnitude\fP provides protocol for those subclasses possessing
a linear ordering.  For the sake of efficiency, most subclasses redefine
some or all of the relational messages.  All methods are defined in
terms of the basic messages <, = and >, which are in turn defined
circularly in terms of each other.  Thus each subclass of \fBMagnitude\fP
must redefine at least one of these messages.
.Rs <
Relational less than test.  Returns a boolean.
.Rs <=
Relational less than or equal test.
.Rs =
Relational equal test.  Note that this differs from ==, which is
an object equality test.
.Rs ~=
Relational not equal test, opposite of =.
.Rs >=
Relational greater than or equal test.
.Rs >
Relational greater than test.
.Rs between:and:
Relational test for inclusion.
.Rs max:
Return the maximum of the receiver and argument value.
.Rs min:
Return the minimum of the receiver and argument value.
.Ex
$A max: $a    $a
4 between: 3.1 and: (17/3)    True
.Nm Object Magnitude Char
.PP
This class defines protocol for objects with character values.
Characters possess an ordering given by the underlying representation,
however arithmetic is not defined for character values.
Characters are written literally by preceding the character desired with
a dollar sign, for example: $a \0 $B \0 $$.
.SH
Responds to
.Rs == r
Object equality test.  Two instances of the same character always test equal.
.Rs asciiValue
Return an \fBInteger\fP representing the ascii value of the receiver.
.Rs asLowercase
If the receiver is an uppercase letter returns the same letter in lowercase,
otherwise returns the receiver.
.Rs asUppercase
If the receiver is a lowercase letter returns the same letter in uppercase,
otherwise returns the receiver.
.Rs asString r
Return a length one string containing the receiver.
Does not contain leading dollar sign, compare to \fIprintString\fP.
.Rs digitValue
If the receiver represents a number (for example $9) return the digit value
of the number.  If the receiver is an uppercase letter (for example $B) return
the position of the number in the uppercase letters + 10, ($B returns 11, for
example).  If the receiver is neither a digit nor an uppercase letter an
error is given and \fBnil\fP returned.
.Rs isAlphaNumeric
Respond true if receiver is either digit or letter, false otherwise.
.Rs isDigit
Respond true if receiver is a digit, false otherwise.
.Rs isLetter
Respond true if receiver is a letter, false otherwise.
.Rs isLowercase
Respond true if receiver is a lowercase letter, false otherwise.
.Rs isSeparator
Respond true if receiver is a space, tab or newline, false otherwise.
.Rs isUppercase
Respond true if receiver is an uppercase letter, false otherwise.
.Rs isVowel
Respond true if receiver is $a, $e, $i, $o or $u, in either
upper or lower case.
.Rs printString r
Respond with a string representation of the character value.
Includes leading dollar sign, compare to \fIasString\fP, which does not include $.
.Ex
$A < $0    False
$A asciiValue    65
$A asString    A
$A printString    $A
$A isVowel    True
$A digitValue    10
.Nm Object Magnitude Number
.PP
The class \fBNumber\fP is an abstract superclass for \fBInteger\fP and \fBFloat\fP.
Instances of \fBNumber\fP cannot be created directly.
Relational messages and many arithmetic messages are redefined in each
subclass for arguments of the appropriate type.  In general, an error message
is given and \fBnil\fP returned for illegal arguments.
.SH
Responds To
.Rs +
Mixed type addition.
.Rs \(mi
Mixed type subtraction.
.Rs *
Mixed type multiplication
.Rs /
Mixed type division.
.Rs \(ua n
Exponentiation, same as raisedTo: .
.Rs @
Construct a point with coordinates being the receiver and the argument.
.Rs abs
Absolute value of the receiver.
.Rs exp
e raised to the power.
.Rs gamma n
Return the gamma function (generalized factorial) evaluated at the
receiver.
.Rs ln
Natural logarithm of the receiver.
.Rs log:
Logarithm in the given base.
.Rs negated
The arithmetic inverse of the receiver.
.Rs negative
True if the receiver is negative.
.Rs pi n
Return the approximate value of the receiver multiplied by \*(p (3.1415926...).
.Rs positive
True if the receiver is positive.
.Rs radians n
Argument converted into radians.
.Rs raisedTo:
The receiver raised to the argument value.
.Rs reciprocal
The arithmetic reciprocal of the receiver.
.Rs roundTo:
The receiver rounded to units of the argument.
.Rs sign
Return \(mi1, 0 or 1 depending upon whether the receiver is negative, zero or
positive.
.Rs sqrt
Square root.  nil if receiver is less than zero.
.Rs squared
Return the receiver multiplied by itself.
.Rs strictlyPositive
True if the receiver is greater than zero.
.Rs to:
Interval from receiver to argument value with step of 1.
.Rs to:by:
Interval from receiver to argument in given steps.
.Rs truncatedTo:
The receiver truncated to units of the argument.
.Ex
3 < 4.1    True
3 + 4.1    7.1
3.14159 exp    23.1406
9 gamma    40320
5 reciprocal    0.2
0.5 radians    0.5 radians
13 roundTo: 5    15
13 truncateTo: 5    10
.Nm Object Magnitude Number Integer
.PP
The class \fBInteger\fP provides protocol for objects with integer values.
.SH
Responds To
.Rs == r
Object equality test.  Two integers representing the same value are
considered to be the same object.
.Rs //
Integer quotient, truncated towards negative infinity (compare to \fIquo:\fP).
.Rs \e\e
Integer remainder, truncated towards negative infinity (compare to \fIrem:\fP).
.Rs allMask:
Argument must be \fBInteger\fP.  Treating receiver and argument as bit strings,
return \fBtrue\fP if all bits with 1 value in argument correspond to bits with 1
values in the receiver.
.Rs anyMask:
Argument must be \fBInteger\fP.  Treating receiver and argument as bit strings,
return true if any bit with 1 value in argument corresponds to a bit with
1 value in the receiver.
.Rs asCharacter
Return the Char with the same underlying ascii representation as the low
order eight bits of the receiver.
.Rs asFloat
Floating point value with same magnitude as receiver.
.Rs bitAnd:
Argument must be \fBInteger\fP.  Treating the receiver and argument as bit strings,
return logical \fBand\fP of values.
.Rs bitAt:
Argument must be \fBInteger\fP greater than 0 and less than underlying word size.
Treating receiver as a bit string, return the bit value at the given position,
numbering from low order (or rightmost) position.
.Rs bitInvert
Return the receiver with all bit positions inverted.
.Rs bitOr:
Return logical \fBor\fP of values.
.Rs bitShift:
Treating the receiver as a bit string, shift bit values by amount indicated
in argument.  Negative values shift right, positive left.
.Rs bitXor:
Return logical \fBexclusive-or\fP of values.
.Rs even
Return true if receiver is even, false otherwise.
.Rs factorial
Return the factorial of the receiver.  Return as Float for large numbers.
.Rs gcd:
Argument must be \fBInteger\fP.  Return the greatest common divisor of the
receiver and argument.
.Rs highBit
Return the location of the highest 1 bit in the receiver.
Return \fBnil\fP for receiver zero.
.Rs lcm:
Argument must be \fBInteger\fP.  Return least common multiple of receiver and
argument.
.Rs noMask:
Argument must be \fBInteger\fP.  Treating receiver and argument as bit strings,
return true if no 1 bit in the argument corresponds to a 1 bit in the receiver.
.Rs odd
Return true if receiver is odd, false otherwise.
.Rs quo:
Return quotient of receiver divided by argument.
.Rs radix:
Return a string representation of the receiver value, printed in the base
represented by the argument.  Argument value must be less than 36.
.Rs rem:
Remainder after receiver is divided by argument value.
.Rs timesRepeat:
Repeat argument block the number of times given by the receiver.
.Ex
5 + 4    7
5 allMask: 4    True
4 allMask: 5    False
5 anyMask: 4    True
5 bitAnd: 3    1
5 bitOr: 3    7
5 bitInvert    \(mi6
254 radix: 16    16rFE
\(mi5 // 4    \(mi2
\(mi5 quo: 4    \(mi1
\(mi5 \e\e 4    1
\(mi5 rem: 4    \(mi1
8 factorial    40320
.Nm Object Magnitude Number Float
.PP
The class \fBFloat\fP provides protocol for objects with floating point values.
.SH
Responds To
.Rs == r
Object equality test.  Return true if the receiver and argument
represent the same floating point value.
.Rs \(ua n
Floating exponentiation.
.Rs arcCos
Return a \fBRadian\fP representing the arcCos of the receiver.
.Rs arcSin
Return a \fBRadian\fP representing the arcSin of the receiver.
.Rs arcTan
Return a \fBRadian\fP representing the arcTan of the receiver.
.Rs  asFloat
Return the receiver.
.Rs ceiling
Return the Integer ceiling of the receiver.
.Rs coerce:
Coerce the argument into being type Float.
.Rs exp
Return e raised to the receiver value.
.Rs floor
Return the Integer floor of the receiver.
.Rs fractionPart
Return the fractional part of the receiver.
.Rs gamma n
Return the value of the gamma function applied to the receiver value.
.Rs integerPart
Return the integer part of the receiver.
.Rs ln
Return the natural log of the receiver.
.Rs radix:
Return a string containing the printable representation of the receiver
in the given radix.  Argument must be an Integer less than 36.
.Rs rounded
Return the receiver rounded to the nearest integer.
.Rs sqrt
Return the square root of the receiver.
.Rs truncated
Return the receiver truncated to the nearest integer.
.Ex
4.2 * 3    12.6
2.1 \(ua 4    19.4481
2.1 raisedTo: 4    19.4481
0.5 arcSin    0.523599 radians
2.1 reciprocal    0.47619
4.3 sqrt    2.07364
.Nm Object Magnitude Radian
.PP
The class \fBRadian\fP is used to represent radians.  Radians are a unit of
measurement, independent of other numbers.
Only radians will responds to the trigonometric functions
such as \fIsin\fP and \fIcos\fP.
Numbers can be converted into
radians by passing them the message \fIradians\fP.  Similarly, radians
can be converted into numbers by sending them the message \fIasFloat\fP.
Notice that only a limited range of arithmetic operations are permitted on
Radians.
Radians are normalized to be between 0 and 2\(*p.
.SH
Responds to
.Rs +
Argument must be a Radian.  Add the two radians together and return the
normalized result.
.Rs \(mi
Argument must be a Radian.  Subtract the argument from the receiver and
return the normalized result.
.Rs *
Argument must be a Number.  Multiply the receiver by the argument amount
and return the normalized result.
.Rs /
Argument must be a Number.  Divide the receiver by the argument amount
and return the normalized result.
.Rs asFloat
Return the receiver as a floating point number.
.Rs cos
Return a floating point number representing the cosine of the
receiver.
.Rs sin
Return a floating point number representing the sine of the receiver.
.Rs tan
Return a floating point number representing the tangent of the receiver.
.Ex
0.5236 radians sin    0.5
0.5236 radians cos    0.866025
0.5236 radians tan    0.577352
0.5 arcSin asFloat    0.523599
.Nm Object Magnitude Point
.PP
\fBPoint\fPs are used to represent pairs of quantities, such as coordinate
pairs.
.SH
Responds To
.Rs <
True if both values of the receiver are less than the corresponding values
in the argument.
.Rs <=
True if the first value is less than or equal to the corresponding value in
the argument, and the second value is less than the corresponding value in
the argument.
.Rs >=
True if both values of the receiver are greater than or equal to the
corresponding values in the argument.
.Rs *
Return a new point with coordinates multiplied by the argument value.
.Rs /
Return a new point with coordinates divided by the argument value.
.Rs //
Return a new point with coordinates divided by the argument value.
.Rs +
Return a new point with coordinates offset by the corresponding values in
the argument.
.Rs abs
Return a new point with coordinates having the absolute value of the
receiver.
.Rs dist:
Return the Euclidean distance between the receiver and the argument
point.
.Rs max:
The argument must be a \fBPoint\fP.
Return the lower right corner of the rectangle defined by the receiver and
the argument.
.Rs min:
The argument must be a \fBPoint\fP.
Return the upper left corner of the rectangle defined by the receiver and
the argument.
.Rs transpose
Return a new point with coordinates being the transpose of the receiver.
.Rs x
Return the first coordinate of the receiver.
.Rs x:
Set the first coordinate of the receiver.
.Rs x:y:
Sets both coordinates of the receiver.
.Rs y
Return the second coordinate of the receiver.
.Rs y:
Set the second coordinate of the receiver.
.Ex
(10@12) < (11@14)    True
(10@12) < (11@11)    False
(10@12) max: (11@11)    11@12
(10@12) min: (11@11)    10@11
(10@12) dist: (11@14)    2.23607
(10@12) transpose    12@10
.Nm Object Random
.PP
The class \fBRandom\fP provides protocol for random number generation.  Sending
the message \fInext\fP to an instance of \fBRandom\fP results in a \fBFloat\fP
between 0.0 and 1.0, randomly distributed.
By default, the pseudo random sequence is the same for each object in class
\fBRandom\fP.  This can be altered using the message \fIrandomize\fP.
.SH
Responds To
.Rs between:and: n
Return a random number uniformly distributed between the two arguments.
.Rs first n
Return a random number between 0.0 and 1.0.
This message merely provides consistency with protocol for other sequences,
such as Arrays or Intervals.
.Rs next
Return a random number between 0.0 and 1.0.
.Rs next: d
Return an \fBArray\fP containing the next n random numbers, where n
is the argument value.
.Rs randInteger: n
The argument must be an integer.  Return a random integer between 1 and the
value given.
.Rs randomize n
Change the pseudo-random number generator seed by a time dependent value.
.Ex
i \(<- Random new
i next    0.759
i next    0.157
i next: 3    #( 0.408 0.278 0.547 )
i randInteger: 12    5
i between: 4 and: 17.5    10.0
.Nm Object Collection
.PP
The class \fBCollection\fP provides protocol for groups of objects, such as
\fBArray\fPs or \fBSet\fPs.
The different forms of collections are distinguished by several
characteristics, among them whether the size of the collection is fixed
or unbounded, the presence or absence of an ordering, and their insertion
or access method.  For example, an \fBArray\fP is a collection with a
fixed size and ordering, indexed by integer keys.  A \fBDictionary\fP, on the
other hand, has no fixed size or ordering, and can be indexed by
arbitrary elements.  Nevertheless, \fBArrays\fP and \fBDictionarys\fP share many
features in common, such as their access method (\fIat:\fP and \fPat:put:\fP),
and the ability to respond to \fIcollect:\fP, \fIselect:\fP, and many other
messages.
.PP
The table below lists some of the characteristics of several forms of
collections:
.TS
center box;
l c c c c c.

Name    Creation    Size    Ordered?    Insertion    Access
    Method    fixed?        method    method

_

Bag/Set    new    no    no    add:    includes:

Dictionary    new    no    no    at:put:    at:

Interval    n to: m    yes    yes    none    at:

List    new    no    yes    addFirst:    first
                addLast:    last

Array    new:    yes    yes    at:put:    at:

String    new:    yes    yes    at:put:    at:

.TE
.PP
The list below shows messages that are shared in common by all collections.
.SH
Responds to
.Rs addAll:
The argument must be a \fBCollection\fP.
Add all the elements of the argument collection to the receiver collection.
.Rs asArray
Return a new collection of type \fBArray\fP containing the elements from
the receiver collection.  If the receiver was ordered, the elements will
be in the same order in the new collection, otherwise the elements will
be in an arbitrary order.
.Rs asBag
Return a new collection of type \fBBag\fP containing the elements from
the receiver collection.
.Rs asList n
Return a new collection of type \fBList\fP containing the elements from
the receiver collection.  If the receiver was ordered, the elements will
be in the same order in the new collection, otherwise the elements will
be in an arbitrary order.
.Rs asSet
Return a new collection of type \fBSet\fP containing the elements from
the receiver collection.
.Rs asString
Return a new collection of type \fBString\fP containing the elements from the
receiver collection.  The elements to be included must all be of type
\fBCharacter\fP.  If the receiver was ordered, the elements will be in the same
order in the new collection, otherwise the elements will be listed in an
arbitrary order.
.Rs coerce:
The argument must be a collection.
Return a collection, of the same type as the receiver, containing elements
from the argument collection.  This message is redefined in most subclasses
of collection.
.Rs collect:
The argument must be a one argument block.
Return a new collection, like the receiver, containing the result of
evaluating the argument block on each element of the receiver collection.
.Rs detect:
The argument must be a one argument block.
Return the first element in the receiver collection for which the
argument block evaluates true.  Report an error and return \fBnil\fP if
no such element exists.
Note that in unordered collections (such as \fBBags\fP or \fBDictionarys\fP) the first
element to be encountered that will satisfy the condition may not be
easily predictable.
.Rs detect:ifAbsent:
Return the first element in the receiver collection for which the
first argument block evaluates true.  Return the result of evaluating
the second argument if no such element exists.
.Rs do:
The argument must be a one argument block.
Evaluate the argument block on each element in the receiver collection.
.Rs includes:
Return true if the receiver collection contains the argument.
.Rs inject:into:
The first argument must be a value, the second a two argument block.
The second argument is evaluated once for each element in the receiver
collection, passing as arguments the result of the previous evaluation
(starting with the first argument) and the element.
The value returned is the final value generated.
.Rs isEmpty
Return true if the receiver collection contains no elements.
.Rs occurrencesOf:
Return the number of times the argument occurs in the receiver collection.
.Rs remove:
Remove the argument from the receiver collection.  Report an error
if the element is not contained in the receiver collection.
.Rs remove:ifAbsent:
Remove the first argument from the receiver collection.  Evaluate the second
argument if not present.
.Rs reject:
The argument must be a one argument block.
Return a new collection like the receiver containing all elements for
which the argument block returns false.
.Rs select:
The argument must be a one argument block.
Return a new collection like the receiver containing all elements for
which the argument block returns true.
.Rs size
Return the number of elements in the receiver collection.
.Ex
i \(<- 'abacadabra'
i size    10
i asArray    #( $a $b $a $c $a $d $a $b $r $a )
i asBag    Bag ( $a $a $a $a $a $r $b $b $c $d)
i asSet    Set ( $a $r $b $c $d )
i occurrencesOf: $a    5
i reject: [:x | x isVowel]    bcdbr
.Nm Object Collection Bag/Set
.PP
\fBBags\fP and \fBSets\fP are each
unordered collections of elements.
Elements in the collections do not have keys, but are added and removed
directly.
The difference between a \fBBag\fP and a \fBSet\fP is that each element can occur
any number of times in a \fBBag\fP, whereas only one copy is inserted into
a \fBSet\fP.
.SH
Responds to
.Rs add:
Add the indicated element to the receiver collection.
.Rs add:withOccurences:
(\fBBag\fP only) Add the indicated element to the receiver \fBBag\fP the given number
of times.
.Rs first n
Return the first element from the receiver collection.
As the collection is unordered, the first element
depends upon certain values in the internal representation, and is
not guaranteed to be any specific element in the collection.
.Rs next n
Return the next element in the collection.
In conjunction with \fIfirst\fP, this can be used to access each
element of the collection in turn.
.Ex
i \(<- (1 to: 6) asBag    Bag ( 1 2 3 4 5 6 )
i size    6
i select: [:x | (x \e\e 2) strictlyPositive]    Bag ( 1 3 5 )
i collect: [:x | x \e\e 3]    Bag ( 0 0 1 1 2 2 )
j \(<- ( i collect: [:x | x \e\e 3] ) asSet    Set ( 0 1 2 )
j size    3
.LP
\fBNote:\fP Since \fBBags\fP and \fBSets\fP are unordered, there is no way to
establish a mapping between the elements of the Bag i in the example above
and the corresponding elements in the collection that resulted from the
message collect: [:x | x \e\e 3].
.Nm Object Collection KeyedCollection
.PP
The class \fBKeyedCollection\fP provides protocol for collections with keys,
such as \fBDictionarys\fP and \fBArrays\fP.
Since each entry in the collection has both a key and value, the
method \fIadd:\fP is no longer appropriate.  Instead, the method
\fIat:put:\fP, which provides both a key and a value, must be used.
.SH
Responds to
.Rs asDictionary
Return a new collection of type \fBDictionary\fP containing the elements
from the receiver collection.
.Rs at:
Return the item in the receiver collection whose key matches the argument.
Produces and error message, and returns nil, if no item is currently in
the receiver collection under the given key.
.Rs at:ifAbsent:
Return the element stored in the dictionary under the key given by the
first argument.  Return the result of evaluating the second argument if
no such element exists.
.Rs atAll:put:
The first argument must be a collection containing keys valid for the
receiver.  At each location given by a key in the first argument place
the second argument.
.Rs binaryDo:
The argument must be a two argument block.  This message is similar to \fIdo:\fP,
however both the key and the element value are passed as argument to the
block.
.Rs includesKey:
Return true if the indicated key is valid for the receiver collection.
.Rs indexOf:
Return the key value of the first element in the receiver collection matching
the argument.
Produces an error message if no such element exists.
Note that, as with the message \fIdetect:\fP, in unordered collections the
first element may not be related in any way to the order in which elements
were placed into the collection, but is rather implementation dependent.
.Rs indexOf:ifAbsent:
Return the key value of the first element in the receiver collection matching
the argument.
Return the result of evaluating the second argument if no such element
exists.
.Rs keys
Return a Set containing the keys for the receiver collection.
.Rs keysDo:
The argument must be a one argument block.
Similar to \fIdo:\fP, except that the values passed to the block are the keys
of the receiver collection.
.Rs keysSelect:
Similar to \fIselect\fP, except that the selection is made on the basis of keys
instead of values.
.Rs removeKey:
Remove the object with the given key from the receiver collection.
Print an error message, and return \fBnil\fP, if no such object exists.
Return the value of the deleted item.
.Rs removeKey:ifAbsent:
Remove the object with the given key from the receiver collection.
Return the result of evaluating the second argument if no such object
exists.
.Rs values
Return a Bag containing the values from the receiver collection.
.Ex
i \(<- 'abacadabra'
i atAll: (1 to: 7 by: 2) put: $e    ebecedebra
i indexOf: $r    9
i atAll: i keys put: $z    zzzzzzzzzz
i keys    Set ( 1 2 3 4 5 6 7 8 9 10 )
i values    Bag ( $z $z $z $z $z $z $z $z $z $z )
#(how odd) asDictionary    Dictionary ( 1 @ #how 2 @ odd )
.Nm Object Collection KeyedCollection Dictionary
.PP
A \fBDictionary\fP is an unordered collection of elements, as are \fBBags\fP
and \fBSets\fP.
However, unlike these collections, elements inserted and removed from
a \fBDictionary\fP must reference an explicit key.  Both the key and value
portions of an element can be any object, although commonly the keys are
instances of \fBSymbol\fP or \fBNumber\fP.
.SH
Responds to
.Rs at:put:
Place the second argument into the receiver collection under the key given
by the first argument.
.Rs currentKey
Return the key of the last element yielded in response to a \fIfirst\fP or
\fInext\fP request.
.Rs first n
Return the first element of the receiver collection.
Return nil if the receiver collection is empty.
.Rs next n
Return the next element of the receiver collection, or nil if no such element
exists.
.Ex
.ta 3i
i \(<- Dictionary new
i at: #abc put: #def
i at: #pqr put: #tus
i at: #xyz put: #wrt
i print    Dictionary ( #abc @ #def #pqr @ #tus #xyz @ #wrt )
i size    3
i at: #pqr    #tus
i indexOf: #tus    #pqr
i keys    Set ( #abc #pqr #xyz )
i values    Bag ( #wrt #def # tus )
i collect: [:x | x asString at: 2]    Dictionary ( #abc @ $e #pqr @ $u #xyz @ $r)
.Nm Object Collection KeyedCollection Dictionary Smalltalk
.PP
The class \fBSmalltalk\fP provides protocol for the pseudo variable
\fBsmalltalk\fP.
Since it is a subclass of Dictionary, this variable can be used to store
information, and thus provide a means of communication between objects.
Other messages modify various parameters used by the Little Smalltalk system.
.SH
Responds To
.Rs date n
Return the current date and time as a string.
.Rs display n
Set execution display to display the result of every expression typed, but
not for assignments.
Note that the display behavior can also be modified using the \-d argument
on the command line.
.Rs displayAssign n
Set execution display to display the result of every expression typed,
including assignment statements.
.Rs doPrimitive:withArguments: n
Execute the indicated primitive with arguments given by the second array.
A few primitives (such as those dealing with process management) cannot be
executed in this manner.
.Rs noDisplay n
Turn off execution display - no results will be displayed unless explicitly
requested by the user.
.Rs perform:withArguments: d
Send indicated message to the receiver, using the arguments given.
The first value in the argument array is taken to be the receiver of
the message.
Unpredictable results if the number of arguments is not appropriate for
the given message.
.Rs sh: n
The argument, which must be a string, is executed as a Unix command by the
shell.  The value returned is the termination status of the shell.
.Rs time: n
The argument must be a block.  The block is executed, and the number of
seconds elapsed during execution returned.  Time is only accurate to within
about one second.
.Ex
smalltalk date    Fri Apr 12 16:15:42 1985
smalltalk perform: #+ withArguments: #(2 5)    7
smalltalk doPrimitive: 10 withArguments: #(2 5)    7
.Nm Object Collection KeyedCollection SequenceableCollection
.PP
The class \fBSequenceableCollection\fP contains protocol for collections that have
a definite sequential ordering and are indexed by integer keys.
Since there is a fixed order for elements, it is possible to refer to the
last element in a \fBSequenceableCollection\fP.
.SH
Responds to
.Rs ,
Appends the argument collection to the receiver collection, returning a new
collection of the same type as the receiver.
.Rs copyFrom:to:
Return a new collection, like the receiver, containing the designated
subportion of the receiver collection.
.Rs copyWith:
Return a new collection, like the receiver, with the argument added to
the end.
.Rs copyWithout:
Return a new collection, like the receiver, with all occurrences of
the argument removed.
.Rs equals:startingAt:
The first argument must be a \fBSequenceableCollection\fP.
Return true if each element of the receiver collection is equal to the
corresponding element in the argument offset by the amount given in
the second argument.
.Rs findFirst:
Find the key for the first element whose value satisfies the
argument block.
Produce an error message if no such element exists.
.Rs findFirst:ifAbsent:
Both arguments must be blocks.
Find the key for the first element whose value satisfies the first argument block.
If no such element exists return the value of the
second argument.
.Rs findLast:
Find the key for the last element whose value satisfies the argument block.
Produce an error message if no such element exists.
.Rs findLast:ifAbsent:
Both arguments must be blocks.
Find the key for the last element whose value satisfies the first argument block.
If no such element exists return the value of the second argument block.
.Rs firstKey
Return the first key valid for the receiver collection.
.Rs indexOfSubCollection:startingAt:
.br
Starting at the position given by the second argument, find the next
block of elements in the receiver collection which match the collection
given by the first argument, and return the index for the start of that block.
Produce an error message if no such position
exists.
.Rs indexOfSubCollection:startingAt:ifAbsent:
.br
Similar to \fIindexOfSubCollection:startingAt:\fP, except that the result of the
exception block is produced if no position exists matching the pattern.
.Rs last
Return the last element in the receiver collection.
.Rs lastKey
Return the last key valid for the receiver collection.
.Rs replaceFrom:to:with:
Replace the elements in the receiver collection in the positions indicated
by the first two arguments with values taken from the collection given
by the third argument.
.Rs replaceFrom:to:with:startingAt:
.br
Replace the elements in the receiver collection in the positions indicated
by the first two arguments with values taken from the collection given
in the third argument, starting at the position given by the fourth
argument.
.Rs reversed n
Return a collection, like the receiver, with elements reversed.
.Rs reverseDo:
Similar to \fIdo\fP:, except that the items are presented in reverse order.
.Rs sort n
Return a collection, like the receiver, with the elements sorted
using the comparison <=.  Elements must be able to respond to the binary
message <=.
.Rs sort: n
The argument must be a two argument block which yields a boolean.
Return a collection, like the receiver, sorted using the argument
to compare elements for the purpose of ordering.
.Rs with:do:
The second argument must be a two argument block.
Present one element from the receiver collection and from the collection
given by the first argument in turn to the second argument block.
An error message is given if the collections do not have the same number of
elements.
.Ex
i \(<- 'abacadabra'
i copyFrom: 4 to: 8    cadab
i copyWith: $z    abacadabraz
i copyWithout: $a    bcdbr
i findFirst: [:x | x > $m]    9
i indexOfSubCollection: 'dab' startingAt: 1    6
i reversed    arbadacaba
i , i reversed    abacadabraarbadacaba
i sort: [:x :y | x >= y]    rdcbbaaaaa
.Nm Object Collection KeyedCollection SequenceableCollection Interval
.PP
The class \fBInterval\fP represents a sequence of numbers in an arithmetic
sequence, either ascending or descending.  Instances of \fBInterval\fP are
created by numbers in response to the message \fIto:\fP or \fIto:by:\fP.
In conjunction with the message \fIdo:\fP, \fBIntervals\fP create a control
structure similar to do or for loops in Algol like languages.  For example:
.DS B
.sp
(1 to: 10) do: [:x | x print]
.sp
.DE
will print the numbers 1 through 10.
Although they are a collection, \fBIntervals\fP cannot be added to.
They can, however, be accessed randomly using the message \fIat\fP:.
.SH
Responds to
.Rs first
Produce the first element from the interval.  In conjunction with
\fIlast\fP, this message may be used to produce each element from the
interval in turn.  Note that \fBIntervals\fP also respond to the message
\fIat:\fP, which can be used to produce elements in an arbitrary order.
.Rs from:to:by:
Initialize the upper and lower bounds and the step size for the receiver.
(This is used principally internally by the method for number to create new
Intervals).
.Rs next
Produce the next element from the interval.
.Rs size
Return the number of elements that will be generated in producing the
interval.
.Ex
(7 to: 13 by: 3) asArray    #( 7 10 13 )
(7 to: 13 by: 3) at: 2    10
(1 to: 10) inject: 0 into: [:x :y | x + y]    55
(7 to: 13) copyFrom: 2 to: 5    #( 8 9 10 11 )
(3 to: 5) copyWith: 13    #( 3 4 5 13 )
(3 to: 5) copyWithout: 4    #( 3 5 )
(2 to: 4) equals: (1 to: 4) startingAt: 2    True
.Nm Object Collection KeyedCollection SequenceableCollection List
.PP
Lists represent collections with a fixed order, but indefinite
size.  No keys are used, and elements are added or removed from one end of
the other.
Used in this way, Lists
can perform as \fIstacks\fP or as \fIqueues\fP.  The table below
illustrates how stack and queue operations can be implemented in terms
of messages to instances of List.
.TS
center;
l s | l s
l l | l l.
\fIstack operations\fP    \fIqueue operations\fP

_
push    addLast:    add    addLast:
pop    removeLast    first in queue    first
top    last    remove first in queue    removeFirst
test empty    isEmpty    test empty    isEmpty
.TE
.SH
Responds to
.Rs add:
Add the element to the beginning of the receiver collection.  This is the same
as \fIaddFirst:\fP.
.Rs addAllFirst:
The argument must be a SequenceableCollection.  The elements of the argument
are added, in order, to the front of the receiver collection.
.Rs addAllLast:
The argument must be a SequenceableCollection.  The elements of the argument
are added, in order, to the end of the receiver collection.
.Rs addFirst:
The argument is added to the front of the receiver collection.
.Rs addLast:
The argument is added to the back of the receiver collection.
.Rs removeFirst
Remove the first element from the receiver collection, returning the
removed value.
.Rs removeLast
Remove the last element from the receiver collection, returning the
removed value.
.Ex
i \(<- List new
i addFirst: 2 / 3    List ( 0.6666 )
i add: $A
i addAllLast: (12 to: 14 by: 2)
i print    List ( 0.6666 $A 12 14 )
i first    0.6666
i removeLast    14
i print    List ( 0.6666 $A 12 )
.Nm Object Collection KeyedCollection SequenceableCollection List Semaphore
.PP
Semaphores are used to synchronize concurrently running \fBProcesses\fP.
.SH
Responds To
.Rs new:
If created using \fInew\fP, a \fBSemaphore\fP starts out with zero excess
signals.  Alternatively, a \fBSemaphore\fP can be created with an arbitrary
number of excess signals by giving it an argument to \fInew\fP:.
.Rs signal
If there is a process blocked on the semaphore is it scheduled for
execution, otherwise
the number of excess signals is incremented by one.
.Rs wait
If there are excess signals associated with the semaphore the number of
signals is decremented by one, otherwise
the current process is placed on the semaphore queue.
.Nm Object Collection KeyedCollection SequenceableCollection File
.PP
A \fBFile\fP is a type of collection where the elements of the collection are
stored on an external medium, typically a disk.
For this reason, although most operations on collections are defined for
files, many can be quite slow in execution.
A file can be opened on one of three \fImodes\fP:
In \fIcharacter\fP mode every read returns a single character from the
file.
In \fIinteger\fP mode every read returns a single word, as an integer value.
In \fIstring\fP mode every read returns a single line, as a \fBString\fP.
For writing, character and string modes will write the string representation
of the argument, while integer mode must write only a single integer.
.SH
Responds To
.Rs at:
Return the object stored at the indicated position.  Position is given as a
character count from the start of the file.
.Rs at:put:
Place the object at the indicated position in the file.  Position is given
as a character count from the start of the file.
.Rs characterMode
Set the mode of the receiver file to \fIcharacter\fP.
.Rs currentKey
Return the current position in the file, as a character count from the
start of the file.
.Rs integerMode
Set the mode of the receiver file to \fIinteger\fP.
.Rs open:
Open the indicated file for reading.
The argument must be a \fBString\fP.
.Rs open:for:
The \fIfor:\fP argument must be one of 'r', 'w' or 'r+'
(see fopen(3) in the Unix programmers
manual).  Open the file in the indicated mode.
.Rs read
Return the next object from the file.
.Rs size
Return the size of the file, in character counts.
.Rs stringMode
Set the mode of the receiver file to \fIstring\fP.
.Rs write:
Write the argument into the file.
.Nm Object Collection KeyedCollection SequenceableCollection ArrayedCollection
.PP
The class \fBArrayedCollection\fP provides protocol for collections with a
Fixed size and integer keys.
Unlike other collections, which are created using the message \fInew\fP,
instances of \fBArrayedCollection\fP must be created using the one argument
message \fInew:\fP.  The argument given with this message must be a positive
integer, representing the size of the collection to be created.
In addition to the protocol shown, many of the methods inherited
from superclasses are redefined in this class.
.SH
Responds to
.Rs =
The argument must also be an \fBArray\fP.  Test whether the receiver and the
argument have equal elements listed in the same order.
.Rs at:ifAbsent:
Return the element stored with the given key.  Return the result
of evaluating the second argument if the key is not valid for the
receiver collection.
.Rs padTo: n
Return an array like the received that is at least as long as the argument
value.  Returns the receiver if it is already longer than the argument.
.Ex
\&'small' = 'small'    True
\&'small' = 'SMALL'    False
\&'small' asArray    #( $s $m $a $l $l)
\&'small' asArray = 'small'    True
#(1 2 3) padTo: 5    #(1 2 3 nil nil)
#(1 2 3) padTo: 2    #(1 2 3)
.Nm Object Collection KeyedCollection SequenceableCollection ArrayedCollection Array
.PP
Instances of the class \fBArray\fP are perhaps the most commonly used
data structure in Smalltalk programs.
\fBArrays\fP are represented textually by a pound sign preceding the list of
array elements.
.SH
Responds to
.Rs at:
Return the item stored in the position given by the argument.
An error message is produced, and \fBnil\fP returned, if the argument is not
a valid key.
.Rs at:put:
Store the second argument in the position given by the first argument.
An error message is produced, and \fBnil\fP returned, if the argument is not
a valid key.
.Rs grow:
Return a new array one element larger than the receiver, with the argument
value attached to the end.  This is a slightly more efficient command than
\fIcopyWith:\fP, although the effect is the same.
.Ex
i \(<- #(110 101 97)
i size    3
i \(<- i grow: 116    #( 110 101 97 116)
i \(<- i collect: [:x | x asCharacter]    #( #n #e #a #t )
i asString    neat
.Nm Object Collection KeyedCollection SequenceableCollection ArrayedCollection ByteArray
.PP
A \fBByteArray\fP is a special form of array in which the elements must be
numbers in the range 0-255.  Instances of \fBByteArray\fP are given a very
compact encoding, and are used extensively internally in the Little
Smalltalk system.
A \fBByteArray\fP can be represented textually by a pound sign preceding
the list of array elements surrounded by a pair of square braces.
.SH
Responds to
.Rs at:
Return the item stored in the position given by the argument.
An error message is produced, and \fBnil\fP returned, if the argument is not
a valid key.
.Rs at:put:
Store the second argument in the position given by the first argument.
An error message is produced, and \fBnil\fP returned, if the argument is not
a valid key.
.Ex
i \(<- #[110 101 97]
i size    3
i \(<- i copyWith: 116    #[ 110 101 97 116 ]
i \(<- i asArray collect: [:x | x asCharacter]    #( #n #e #a #t )
i asString    neat
.Nm Object Collection KeyedCollection SequenceableCollection ArrayedCollection String
.PP
Instances of the class \fBString\fP are similar to \fBArrays\fP, except
that the individual elements
must be \fBCharacter\fP.  \fBStrings\fP are represented literally by placing single
quote marks around the characters making up the string.
\fBStrings\fP also differ from \fBArrays\fP in that
Strings possess an ordering, given by the underlying ascii sequence.
.SH
Responds to
.Rs ,
Concatenates the argument to the
receiver string, producing a new string.
If the argument is not a \fBString\fP it is first converted
using \fIprintString\fP.
.Rs <
The argument must be a \fBString\fP.  Test if the receiver is lexically
less than the argument.  For the purposes of comparison case differences
are ignored.
.Rs <=
Test if the receiver is lexically less than or equal to the
argument.
.Rs >=
Test if the receiver is lexically greater than or equal to the argument.
.Rs >
Test if the receiver is lexically greater than the argument.
.Rs asSymbol r
Return a \fBSymbol\fP with characters given by the receiver string.
.Rs at:
Return the character stored at the position given by the argument.
Produce and error message, and return \fBnil\fP, if the argument does not represent
a valid key.
.Rs at:put:
Store the character given by second argument at the location given by
the first argument.  Produce an error message, and return \fBnil\fP, if either
argument is invalid.
.Rs copyFrom:length: n
Return a substring of the receiver.  The substring is taken from the
indicated starting position in the receiver and extends for the given length.
Produce an error message, and return \fBnil\fP, if the given positions are
not legal.
.Rs copyFrom:to: r
Return a substring of the receiver.  The substring is taken from the
indicated positions.
Produce an error message, and return \fBnil\fP, if the given positions are
not legal.
.Rs printAt: n
The argument must be a \fBPoint\fP which describes a location on the
terminal screen.  The string is printed at the specified location.
.Rs size
Return the number of characters stored in the string.
.Rs sameAs:
Return true if the receiver and argument string match with the exception of
case differences.  Note that the boolean message = , inherited from
ArrayedCollection, can be used to see if two strings are the same including
case differences.
.Ex
\&'example' at: 2    $x
\&'bead' at: 1 put: $r    read
\&'small' > 'BIG'    True
\&'small' sameAs: 'SMALL'    True
\&'tary' sort    arty
\&'Rats live on no evil Star' reversed    ratS live on no evil staR
.Nm Object Block
.PP
Although it is easy for the programmer to think of blocks as a syntactic
construct, or a control structure, they are actually objects, and share
attributes of all other objects in the Smalltalk system, such as the
ability to respond to messages.
.SH
Responds to
.Rs fork
Start the block executing as a \fBProcess\fP.
The value \fBnil\fP is immediately returned,
and the \fBProcess\fP created from the block
is scheduled to run in parallel with the current process.
.Rs forkWith:
Similar to \fIfork\fP, except that the array is passed as arguments to the
receiver block prior to scheduling for execution.
.Rs newProcess
A new \fBProcess\fP is created for the block, but is not
scheduled for execution.
.Rs newProcessWith: n
Similar to \fInewProcess\fP, except that the array is passed as arguments to the
receiver block prior to it being made into a process.
.Rs value
Evaluates the receiver block.  Produces an error message, and returns nil,
if the receiver block required arguments.  Return the value yielded by
the block.
.Rs value:
Evaluates the receiver block.  Produces an error message, and returns nil,
if the receiver block did not require a single argument.  Return the
value yielded by the block.
.Rs value:value:
Two argument block evaluation.
.Rs value:value:value:
Three argument block evaluation.
.Rs value:value:value:value:
Four argument block evaluation.
.Rs value:value:value:value:value:
.br
Five argument block evaluation.
.Rs whileTrue:
The receiver block is repeatedly evaluated.  While it evaluates to true,
the argument block is also evaluated.  Return nil when the receiver block
no longer evaluates to true.
.Rs whileTrue
The receiver block is repeatedly evaluated until it returns a value that is
not true.
.Rs whileFalse:
The receiver block is repeatedly evaluated.  While it evaluates to false,
the argument block is also evaluated.  Return nil when the receiver block
no longer evaluates to false.
.Rs whileFalse
The receiver block is repeatedly evaluated until it returns a value that is
not false.
.Ex
['block indeed'] value    block indeed
[:x :y | x + y + 3] value: 5 value: 7    15
.Nm Object Class
.PP
The class \fBClass\fP provides protocol for manipulating class instances.
An instance of class \fBClass\fP is generated for each class in the Smalltalk
system.  New instances of this class are then formed by sending messages
to the class instance.
.SH
Responds to
.Rs deepCopy: n
The argument must be an instance of the receiver class.  A deepCopy
of the argument is returned.
.Rs edit n
The user is placed into a editor editing the file from which the class
description was originally obtained.  When the editor terminates, the class
description will be reparsed and will override the previous description.
See also \fIview\fP (below).
.Rs list n
Lists all subclasses of the given class recursively.
In particular, \fBObject\fP \fIlist\fP will list the names of all the
classes in the system.
.Rs new
A new instance of the receiver class is returned.  If the methods for
the receiver contain protocol for \fInew\fP, the new instance will
first be passed this message.
.Rs new:
A new instance of the receiver class is returned.  If the methods for
the receiver contain protocol for \fInew:\fP, the new instance will
first be passed this message.
.Rs respondsTo n
List all the messages that the current class will respond to.
.Rs respondsTo: d
The argument must be a Symbol.  Return true if the receiver class,
or any of its superclasses, contains a method
for the indicated message. Return false otherwise.
.Rs shallowCopy: n
The argument must be an instance of the receiver class.  A shallowCopy
of the argument is returned.
.Rs superClass n
Return the superclass of the receiver class.
.Rs variables n
Return an array containing the names of the instance variables used in
the receiver class.
.Rs view n
Place the user into an editor viewing the class description from which the
class was created.  Changes made to the file will not, however, affect the
current class representation.
.Ex
Array new: 3    #( nil nil nil )
Bag respondsTo: #add:    True
SequenceableCollection superClass    KeyedCollection
.Nm Object Process
.PP
Processes are created by the system, or by passing the message \fInewProcess\fP
or \fIfork\fP to a block; they cannot be created directly by the user.
.SH
Responds To
.Rs block
The receiver process is marked as being blocked.  This is usually
the result of a semaphore wait.
Blocked processes are not executed.
.Rs resume
If the receiver process has been \fIsuspend\fPed, it is rescheduled for
execution.
.Rs suspend
If the receiver process is scheduled for execution, it is marked as
suspended.  Suspended processes are not executed.
.Rs state
The current state of the receiver process is returned as a Symbol.
.Rs terminate
The receiver process is terminated.  Unlike a blocked or suspended process,
a terminated process cannot be restarted.
.Rs unblock
If the receiver process is currently blocked, it is scheduled for
execution.
.Rs yield
Returns \fBnil\fP.  As a side effect, however,
if there are pending processes the current process is
placed back on the process queue and another process started.