Celestin Apprentice 2

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Text File | 1992-11-27 | 13.0 KB | 292 lines | [TEXT/MSET]

CLASS DEFINITION :CLASS -- : name super{ cname1 cname2 } opt Begins definition of a new class. One or more classnames can be designated as superclass(es). There are optional parameters that may also be declared after the superclass list, including n INDEXED, LARGE, and GENERAL. ;CLASS -- Ends definition of a class. SUPER{ -- : cname1 cname2 } opt Used to declare the superclass(es) when defining a class. See :class. GENERAL -- Optional class declaration that will allow late binding when this class is used as an ivar. But note that GENERAL classes may not be used to map ivars to Mac toolbox calls because the class header information will be included. INDEXED classes are automatically GENERAL. LARGE -- Sets the "large" option on an indexed class, allowing the number of elements to be greater than 32K. INDEXED n -- Sets a class and its subclasses to indexed, of element byte width n. Used after the superclass declaration list when defining a new class. Note that when instantiating an indexed class, you MUST precede the instance name with the number of elements you wish that instance to have. Also note that all indexed classes are automatically declared to be GENERAL, so you may not used indexed classes to map into toolbox calls. Also, n must be < 32K (see LARGE). :M -- : name: Begins definition of a method within a class. Note that name: MUST end with a colon (:). ;M -- Ends definition of a method in a class. PRIVATE -- Use within a class definition. Makes the following methods private—that is, they will be accessible from within this class or any of its subclasses, but not from anywhere else. The criterion is simply that a call to Self of Super may access a private method, but nothing else can. Note that for this reason you can't late-bind to a private method, even if you do it from within the class itself. PUBLIC -- Makes the following methods public—that is, they will be accessible from anywhere. PRIVATE and PUBLIC may be used any number of times within the one class definition. Methods are initially public when a class compilation starts. CallFirst -- : methodname: The next method definition will always execute the method indicated by methodname: BEFORE it is executed by a subclass. Provides a way for superclasses to limit the extent to which subclasses may override a method. CallLast -- : methodname: The next method definition will always execute the method indicated by methodname: AFTER it is executed by a subclass. Provides a way for superclasses to limit the extent to which subclasses may override a method. SELF -- obj Object reference to self. Only used in a class definition. SELF is not necessarily the same as ^BASE, because of multiple inheritance. SUPER -- obj Use within a class method definition to refer to self, an instance of the class, but the superclass method will be invoked. LATE BINDING [ -- Begins an expression with a late bound message that computes the address of the object to recieve the message. e.g. get: [ 0 at: anArray ] . This is an alternative syntax to that provided by **, [], and [self]. ] -- See above. note that [SELF], [], and ** are all synonyms. [SELF] obj selid -- Late binds whatever is on the stack to the given method. e.g. obj get: [self] . You must be sure that obj really does point to an object. [] ^obj selid -- See above. ** ^obj selid -- See above. STANDARD METHODS CLASSINIT: -- Our standard constructor method. The default message that is ALWAYS sent to an object at time of instantiation, even ivars. Note that if parameters are to be included for a classinit: for an INDEXED class, the #elements must precede those parameters (#elems must be top item on stack) at instantiation time (read that again). Note that for class object classinit: is a null method, that is it does nothing. ADDR: -- ^base Returns the address of the beginning of an object's ivars. CLASS: -- class Returns the class pointer for an object. COPYTO: obj -- Copies the ivar part of the passed in object to self. Doesn't check type - be careful. DUMP: -- Performs a formatted dump of a class. LENGTH: -- len Gets total length of object. Length will include class header information only if class is of type GENERAL. Otherwise, length is merely the length of the ivar data field(s). PRINT: -- Use to display a class, default is just a DUMP:. RELEASE: -- Our standard destructor method. Any objects that allocate heap storage will redefine this appropriately. Our convention is that an object will release ALL its storage when it gets a release: message. Other methods can be provided to partly release storage, as needed. CONSOLE INSPECTION .CLASS: -- A method. Prints the name of the class of the given object. .ID: -- A method. Prints the name of the given object, if it has a name. MISCELLANEOUS BYTES n -- : ivarname Bytes is used as the ivar allocation primitive for basic classes. Allocates n bytes as a named instance variable of an object. You can use bytes to map a Toolbox data structure as an object when named access to some of the fields is not needed (but you must know the proper length). BIND_WITH obj --<selector> obj-modified cfa If you are late-binding in a loop, it can be much faster if you do the bind just once, then reuse the resulting cfa each time in the loop. This way you only have to perform the method search once. To bind initially and get the cfa, use BIND_WITH. Usage: (saveCfa and ^obj-mod are values or locals). (get object's address) bind_with someSelector: -> saveCfa -> ^obj-mod. (in the loop) ^obj-mod saveCfa ex-method. SET_CLASS obj theClass -- SET_CLASS is a utility word used to patch nucleus objects when their classes are defined in higher-level files. Actually it could be used to change the class of any object, if anyone is silly enough to want to do that. SET_TO_CLASS objPtr -- : cname If you need to declare the object pointer before the class exists, use SET_TO_CLASS once the class is defined, thus: ' someOP set_to_class someClass. STANDARD CLASSES (COL) -- : name Collections are ordered lists with a current size. We implement them by multiply inheriting the generic (COL) class with the array class of the appropriate width. We use a few tricks to avoid late binding to self in loops. ARRAY #elems -- : name The basic 4-byte cell one-dimension array. Class is INDEXED. BOOL -- : name Subclass of byte. Note that since the datalength of aMops class bool is 1, this class should not be used to map into a Toolbox record of type BOOLEAN because the Pascal type boolean has a length of 2 (Use the Mops class INT for a Toolbox boolean). BYTE -- : name A standard 1-byte variable class. DICADDR -- : name DICADDR is a relocatable dictionary address class - use to store non-executable dictionary addresses. HANDLE -- : name The standard class for handles. HANDLEARRAY #elems -- : name HANDLEARRAY and HANDLELIST are for the implementation of collections of heap-based objects. HandleArray has normal array properties. Use HandleList if the number of elements may grow arbitrarily large, and if indexing isn't so important. HandleArray also includes methods to allow the array to be used as a stack - needed for FileList. HANDLELIST #elems -- : name HANDLELIST allows the implementation of a list of heap-based objects. Unlike HANDLEARRAY, the list can be of indefinite length. We use a heap block to store the handles to the objects contiguously, rather than have a separate block for each handle and link them together. This saves on memory overhead and reduces the number of memory manager calls. It also reflects the assumption that insertions and deletions into the middle of the list will be infrequent, as these could be more inefficient than with a linked scheme. We expect that elements will normally be added to the end, and probably not removed at all, or not very often. INDEXED-OBJ -- : name Class INDEXED-OBJ is the generic superclass for all arrays. Here we define the general indexed methods, which apply regardless of indexed width. LONGWORD -- : name Generic superclass for var, handle etc. OBJHANDLE -- : name An OBJHANDLE is a handle that points to an object in the heap. OBJPTR -- : name An object pointer is a "low-level" entity, rather like a value. The syntax for object pointers is: objPtr anObjptr class_is theClass OBJ_ARRAY #elems -- : name OBJ_ARRAY is a generic superclass which makes it easy to generate an array of objects of a given class. Just define a new class which multiply inherits from the given class (or classes) and OBJ_ARRAY (which must come last). This will add an indexed section to each object of the new class, with elements wide enough to contain objects of the original class. Then SELECT: "switches in" the selected element to be the "current" element, and all the normal methods of the class can then be used. Note the use of"32767 indexed" in the class definition. ORDERED-COL #elems -- : name Ordered-Collection is a collection of 4-byte cells. A subclass of (col) and array. PTR -- : name A standard class. For toolbox pointers. RESOURCE -- : name Provides basic support for Toolbox resources. SEQUENCE #elems -- j : name A generic superclass for classes which have multiple items which frequently need to be looked at in sequence. At present the main function of Sequence is to implement the EACH: method, which makes it very simple to deal with each element. Sequence can be multiply inherited with any class which implements the FIRST?: and NEXT?: methods. The actual implementation details are quite irrelevant, as long as these methods are supported. VAR -- : name The standard variable class. Subclass of longword that adds the +: and -: methods. Useful as an ivar that maps into a Toolbox LONGINT record structure. X-ADDR -- : name X-ADDR is an executable dictionary address class. The only significant difference to DicAddr is that there is an Exec: method and no Get: method. But if we ever have to separate code and data, having a separate class could prove very useful. X-ARRAY #elems -- : name A subclass of ARRAY, can execute its elements (which are cfas of Mops words). X-COL #elems -- : name X-COL is a collection of executable word addresses. A subclass of (col) and x-array. PRIMITIVES ^BASE -- addr Addr is the base address of the private data of the object. Only used in a class definition. Same as addr: self. OBJ -- obj Called from within an inline method. Passes the object's base and displacement to Handlers to generate the correct address. Optimization will then apply. OBJECT -- class The root class of all classes. Only used as a declared superclass when defining a new class. Note that class object has the pre-defined methods class:, .id:, .class:, addr:, length:, copyto:, classinit:, release:, dump:, and print:. So ALL objects possess these methods. Some of these methods do nothing, for class object. OBJLEN -- n Computes total data length of current object. CHKSAME obj -- obj A check that two objects are of exactly the same class. Aborts with error message if not. CHKCLASS cfa -- cfa Aborts and issues error message if the cfa does not refer to a class. ?>CLASS obj -- class Converts the pointer to an object to a pointer to its class. Aborts if failure. ?CLASS -- Error if not compiling a class definition. CL1 -- Cleans up the class compiler data on an abort. CL>LEN #els class -- #els len Gets data length of object given #els and class. DFA class -- dfa Given a pointer to a class, returns the data field address. First 2 bytes are the data length, second 2 bytes are the width of the indexed elements. DLEN&XWID class -- dlen xwid Given a class pointer, retuns the ivar datalength and width of the indexed elements. EXMID obj selID -- Executes a method given its sel ID. Used in late binding. FFA ^class -- ffa Given a pointer to a class, returns the flag field address. FINDM selID class -- offs cfa Finds a method in a class. GETDLEN obj -- n Gets length of object's named ivars. IFA class -- ifa Given a pointer to a class, returns the ivar field address. IVFINDM selID ^ivar -- offs cfa Looks for a method in IX -- ifa Called from within an inline method. Compiles code to generate the indexed address. META -- class META is the super class of Object - top of all inheritance. MFA class -- mfa Given a pointer to a class, returns the methods field address. RELCNT -- n A value. For testing - counts release: msgs to make sure we're releasing everything. SFA class -- sfa Given a pointer to a class, returns the superclass field address, which is an N-way pointer. SUPER( -- : cname1 cname2 } opt Synonym for super{. XWID class -- xwid Given a class pointer, retuns the width of the indexed elements. ^CLASS -- class Addr of the class we're currently compiling. ^DLEN obj -- dfa Returns the dfa for the given object. ^ELEM idx -- addr Leaves addr of indexed element.