segunda-feira, março 21, 2005

PowerBuilder 9 - About libraries

Whenever you save an object, such as a window or menu, in a painter, PowerBuilder stores the object in a library (a PBL file). Similarly, whenever you open an object in a painter, PowerBuilder retrieves the object from the library.
Assigning libraries
PowerScript targets can use as many libraries as you want. Libraries can be on your own PC or workstation or on a server. When you create a target, you specify which libraries it uses. You can also change the library search path for a target at any time during development.
For information about specifying the library search path, see "Specifying the target's library search path".
How the information is saved
Every object is saved in two parts in a library:
Source form This is a syntactic representation of the object, including the script code.
Object form This is a binary representation of the object, similar to an object file in the C and C++ languages. PowerBuilder compiles an object automatically every time you save it.
Using libraries
It is hard to predict the needs of a particular application, so the organization of a target's libraries generally evolves over the development cycle. PowerBuilder lets you reorganize your libraries easily at any time.
About library size
For small applications, you might use only one library, but for larger applications, you should split the application into different libraries.
There are no limits to how large libraries can be, but for performance and convenience, you should follow these guidelines:
Number of objects It is a good idea not to have more than 50 or 60 objects saved in a library. This is strictly for your convenience; the number of objects does not affect performance. If you have many objects in a library, list boxes that list library objects become unmanageable and the System Tree and Library painter become more difficult to use.
Balance Managing a large number of libraries with only a few objects makes the library search path too long and can slow performance by forcing PowerBuilder to look through many libraries to find an object. Try to maintain a balance between the size and number of libraries.
Organizing libraries
You can organize your libraries any way you want. For example, you might put all objects of one type in their own library, or divide your target into subsystems and place each subsystem in its own library.
Sharing objects with others
PowerBuilder provides basic source control using the PBNative check in/check out utility. PBNative allows you to lock the current version of PowerBuilder objects and prevents others from checking out these objects and modifying them while you are working on them.
The project administrator must design a directory hierarchy for the project's workspace. The administrator might create a separate subdirectory for each target in the workspace, or for each PBL in the workspace. After the administrator sets up the project and registers every object in the workspace, individual developers copy a template workspace to their own computers, open the workspace, and connect to source control.
PowerBuilder also provides a direct connection to external SCC-compliant source control systems.
For more about using PBNative and other source control systems, see "Using a source control system with PowerBuilder".

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