Power GUI Programming with VisualAge C++/powergui.iso/trialva/ibmcppw/help/lxsghelp.hlp

OS/2 Help File | 1996-02-22 | 12.1 KB | 294 lines

ΓòÉΓòÉΓòÉ 1. Collection Class SmartGuide Help ΓòÉΓòÉΓòÉ

The Collection Class SmartGuide helps you choose the appropriate Collection
type for your application.

In this SmartGuide, you select from the following four basic properties:

 o Whether the class elements are ordered or unordered

 o Whether the class uses keys in accessing elements in the collection

 o Whether equality is defined for the element

 o Whether any given element or key is unique, or whether multiple occurrences
   of the same element or key are allowed.

 You can use this SmartGuide either in Novice or Expert mode.  In Novice mode,
 the SmartGuide walks you through the selection of the appropriate Collection
 class.  In Expert mode, you are assumed to know the Collection type that you
 want to use and you are simply prompted for the name of the collection,
 element type, and key type. You can also choose the implementation variant
 based on the performance and storage characteristics of your application.

 This SmartGuide generates C++ source code that uses the Collection class you
 have selected.  It also generates the required functions for the element type
 and key type.

 To use this SmartGuide, make the selection by clicking on the appropriate
 radio button, then press the Next push button. You can return to a previous
 SmartGuide page and change your selection by pressing the Back pushbutton.

 When you are satisfied with your selections, press the Done push button.  The
 source code will be generated in your Edit session, starting at the current
 location of the cursor.  Optionally, the usage code can be generated in a
 separate file. screen.


ΓòÉΓòÉΓòÉ 1.1. Novice ΓòÉΓòÉΓòÉ

Select this button if you want help in selecting the appropriate Collection
type.  When you select this button, the subsequent SmartGuide pages will walk
you through the selection of the appropriate Collection type. You will be
prompted for the class attributes that you want to use in your application,
like key access and equality. You can also specify if you want the usage code
to be generated or not, and if you want the usage code to be generated in a
separate file.


ΓòÉΓòÉΓòÉ 1.2. Expert ΓòÉΓòÉΓòÉ

Select this button if you have already made the decision on the appropriate
Collection class that you want to use in your application. When you select this
button, the next SmartGuide page will simply prompt for the following
information about your class and its elements: collection type, collection
name, element type, and key type.


ΓòÉΓòÉΓòÉ 1.3. Ordered Collection ΓòÉΓòÉΓòÉ

Select this button if the elements in the class will have a next or previous
relationship with each other. Ordered collections can either be sorted or
sequential.  Sorted collections have their elements sorted by an ordering
relation defined for the element type. Sequential collections have their
ordering determined by an explicit qualifier.


ΓòÉΓòÉΓòÉ 1.4. Unordered Collection ΓòÉΓòÉΓòÉ

Select this button if the elements in the class will not have a next or
previous relationship with each other, that is, it is unordered .


ΓòÉΓòÉΓòÉ 1.5. Key Access ΓòÉΓòÉΓòÉ

Select this button if the collection will have a key defined for its elements.
Keys allow you to organize the elements in a collection, and access a specific
element in the collection. If you select this button, the SmartGuide will
generate the appropriate key type functions .


ΓòÉΓòÉΓòÉ 1.6. No Key Access ΓòÉΓòÉΓòÉ

Select this button if the collection will not have a key defined for its
elements.


ΓòÉΓòÉΓòÉ 1.7. Element Equality ΓòÉΓòÉΓòÉ

Select this button if you want to define an equality relation for the elements
of the collection.  When two elements are equal, all data members of both
elements are equal.


ΓòÉΓòÉΓòÉ 1.8. No Element Equality ΓòÉΓòÉΓòÉ

Select this button if you do not want to define an equality relation for the
elements of the collection.


ΓòÉΓòÉΓòÉ 1.9. Unique ΓòÉΓòÉΓòÉ

Select this button if you do not want two keys or two elements to be equal,
that is, they are unique collections .


ΓòÉΓòÉΓòÉ 1.10. Multiple ΓòÉΓòÉΓòÉ

Select this button if you will allow two equal elements, or elements with equal
keys in the collection, that is, they are multiple collections .


ΓòÉΓòÉΓòÉ 1.11. No Restriction ΓòÉΓòÉΓòÉ

Select this button if you do not want restricted access to the collection.
Collections with restricted access have a restricted set of functions that can
be applied to them.


ΓòÉΓòÉΓòÉ 1.12. Restrict Priority ΓòÉΓòÉΓòÉ

Select this button if you want an element to be placed in the collection
according to its key value or priority . The highest priority is indicated by
the lowest key value.


ΓòÉΓòÉΓòÉ 1.13. Sorted ΓòÉΓòÉΓòÉ

Select this button if you want the elements of the collection to be arranged by
an ordering relation defined for the element type. The ordering relation is
determined by the instantiations of the collection class.


ΓòÉΓòÉΓòÉ 1.14. Sequential ΓòÉΓòÉΓòÉ

Select this button if you want the ordering of elements in the collection to be
determined by an explicit qualifier.


ΓòÉΓòÉΓòÉ 1.15. Stack ΓòÉΓòÉΓòÉ

Select this button if you want the elements in the collection to be added or
removed on a last-in, first-out (LIFO) basis.


ΓòÉΓòÉΓòÉ 1.16. Queue ΓòÉΓòÉΓòÉ

Select this button if you want the elements in the collection to be added or
removed on a first-come, first-served basis.


ΓòÉΓòÉΓòÉ 1.17. Double Ended Queue ΓòÉΓòÉΓòÉ

Select this button if you want the elements in the collection to be added or
removed from the two ends of the queue, that is, from the "fresh" end and the
"old" end.


ΓòÉΓòÉΓòÉ 1.18. Collection Type ΓòÉΓòÉΓòÉ

Enter the name of the Collection class type that you want to use. This can be
any of the following:

 o Bag

 o Deque

 o Equality Sequence

 o Heap

 o Key Bag

 o Key Set

 o Key Sorted Bag

 o Key Sorted Set

 o Map

 o Priority Queue

 o Queue

 o Relation

 o Sequence

 o Set

 o Sorted Bag

 o Sorted Map

 o Sorted Relation

 o Sorted Set

 o Stack


ΓòÉΓòÉΓòÉ 1.19. Collection Name ΓòÉΓòÉΓòÉ

Enter the name of the collection class that will be instantiated in the
generated code.


ΓòÉΓòÉΓòÉ 1.20. Element Type ΓòÉΓòÉΓòÉ

Enter the type of the elements that will comprise the collection. This type can
either be predefined or user-defined.


ΓòÉΓòÉΓòÉ 1.21. Key Element Type ΓòÉΓòÉΓòÉ

Enter the key type for the collection.  This type can either be predefined or
user-defined.


ΓòÉΓòÉΓòÉ 1.22. Table ΓòÉΓòÉΓòÉ

Select this button if the collection is primarily used for reading data but the
elements are not frequently added or deleted once the collection is created.
Use a table implementation if all of the following are true:

 o The elements to be stored are small.

 o You can predict with some accuracy how many elements your application will
   be handling.

 o Few or no elements will need to be added or deleted once the collection is
   first created.


ΓòÉΓòÉΓòÉ 1.23. Diluted Table ΓòÉΓòÉΓòÉ

Select this button if some elements of the collection are inserted or deleted
after the collection is created, and if the collection is primarily read from,
rather than written to.


ΓòÉΓòÉΓòÉ 1.24. List ΓòÉΓòÉΓòÉ

Select this button when you anticipate that many elements will be added or
deleted, and when you cannot accurately predict the maximum size of the
collection when it is first created. In a List implementation, storage is
dynamically allocated and freed.


ΓòÉΓòÉΓòÉ 1.25. AVL Tree ΓòÉΓòÉΓòÉ

The AVL Tree is a special form of binary search tree that maintains balance. An
AVL tree is suitable for a collection that contains a large number of small
elements.  It is also suitable for adding and deleting, because the performance
overhead for the rebalancing that sometimes occurs when an element is added or
deleted is still less expensive than searching through the elements of a
sequence to find the position at which to add or delete an element.


ΓòÉΓòÉΓòÉ 1.26. B* Tree ΓòÉΓòÉΓòÉ

A B* Tree implementation variant is suitable when you have many large elements
that are accessed by key. Because keys and their data are separated, the keys
in the tree structure are used for quick search and the pointers are used for
quick access of the data.


ΓòÉΓòÉΓòÉ 1.27. Hash Table ΓòÉΓòÉΓòÉ

In this implementation, an index is calculated from the key or other parts of
an element.  This index is used to look for matches in a hash table. A hash
table implementation is suitable for nearly all applications with a balanced
mix of operations.  Such an implementation is quick for retrieving elements.
It can also add and delete elements quickly, because unlike an AVL tree, it
does not need to be rebalanced.  The efficiency of a hash table implementation
is largely dependent on how efficiently you implement the hash function.


ΓòÉΓòÉΓòÉ 1.28. Main program ΓòÉΓòÉΓòÉ

If you enable this checkbox, a main program containing usage code will be
generated for you. If you disable this checkbox, no main program will be
generated, only the class declarations.


ΓòÉΓòÉΓòÉ 1.29. File Stem ΓòÉΓòÉΓòÉ

Enter the base name (or file stem) of the file that will be generated for your
application.  If you enter a name in this field, the main program will be
generated in the specified file with a .cpp extension.  The class declarations
will be generated in the current Edit session, starting at the current location
of the cursor.  You must save the file containing this generated class
declarations as a .hpp file using the same file stem.