Introduction
Object Pascal must have a CODE segment named %_MethTables in order to
access object methods. In MacApp this is taken care of "behind the scenes" so
you don't have to worry about it . However, if you are doing a straight Object
Pascal program, you must make sure that %_MethTables is around when
you need it. If it's unloaded when you call a method, your Macintosh will begin
executing wild noncode and die a gruesome and horrible death.
The MPW Pascal compiler must see some declaration of an object in order to
produce a reference to the magic segment. You can achieve this cheaply by
simply including ObjIntf.p in your Uses declaration. This
must be in the main program, by the way. The compiler will produce a call to
%_InitObj which is in %_MethTables.
If you're a more adventurous soul, you can call %_InitObj explicitly
from the initialization section of your main program (you must use the
{$%+} compiler directive to allow the use of "%" in
identifiers). This will load the %_MethTables segment. See Technical
Note #93 for ideas about locking down segments that are needed forever without
fragmenting the heap.
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References
M.PT.MPWLoad
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