Inside Macintosh: Mac OS Runtime Architectures /

Chapter 3 - Programming for the CFM-Based Runtime Architecture

Using the Main Symbol as a Data Structure

As mentioned before, the main symbol does not have to point to a routine, but can point to a block of data instead. You can use this fact to good effect with plug-ins, where the block of data referenced by the main symbol can contain essential information about the plug-in. Using the main symbol in this fashion has several advantages:

• The Code Fragment Manager returns the address of the main symbol when you programmatically prepare a fragment, so you do not need to call FindSymbol.
• You do not have to reserve and document the specific name of an export for your plug-in.

However, not having a specific symbol name means that the plug-in's purpose is not quite as obvious.

A plug-in can store its name, icon, or information about its symbols in the main symbol data structure. Storing symbolic information in this fashion eliminates the need for multiple FindSymbol calls.

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© Apple Computer, Inc.
11 MARCH 1997

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