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improve instance variable hiding

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git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@29779 72102866-910b-0410-8b05-ffd578937521
This commit is contained in:
Richard Frith-MacDonald 2010-02-26 10:25:35 +00:00
parent f088bceae8
commit e43d625338
7 changed files with 108 additions and 105 deletions
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54
Source/GSInternal.h
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@ -27,49 +27,43 @@
* their code when the class implementation is changed in new versions of the
* library.
*
* The public class MUST contain an instance variable 'id _internal;' to be
* used as a pointer to a private class containing the ivars.
* The public class MUST contain a use of the GS_INTERNAL() macro with the
* class name as it's argument.
*
* Before including the header file containing the public class declaration,
* you must define GS_X_IVARS (where X is the class name) to be the
* list of actual instance variable declarations for the class.
*
* Before including this file, you must define 'GSInternal' to be the name
* of your public class with * 'Internal' appended.
* eg. if your class is called 'MyClass' then use the following define:
* #define GSInternal MyClassInternal
*
* After including this file you can use the GS_BEGIN_INTERNAL() and
* GS_END_INTERNAL() macros to bracket the declaration of the instance
* variables.
* After including this file you can use the GS_PRIVATE_INTERNAL() macro
* to declare the private subclass used to hold real instance variables.
* The argument to this macro is the public class name (the GS_X_IVARS
* list must also be defined).
*
* You use GS_CREATE_INTERNAL() in your intialiser to create the object
* holding the internal instance variables, and GS_DESTROY_INTERNAL() to
* get rid of that object (only do this if '_internal' is not nil) in
* your -dealloc method.
* get rid of that object in your -dealloc method.
*
* Instance variables are referenced using the 'internal->ivar' suntax or
* the GSIV(classname,object,ivar) macro.
*
* ARGH FIXME ... the following idea doesn't work ... need to rethink/rwrite.
*
* If built with CLANG, with support for non-fragile instance variables,
* rather than GCC, the compiler/runtime can simply declare instance variables
* within the implementation file so that they are not part of the public ABI,
* in which case the macros here mostly reduce to nothing and the generated
* code can be much more efficient.
*/
#if 1 || !__has_feature(objc_nonfragile_abi)
#if !GS_NON_FRAGILE
/* Code for when we don't have non-fragine instance variables
/* Code for when we don't have non-fragile instance variables
*/
/* Start declaration of internal ivars.
*/
#define GS_BEGIN_INTERNAL(name) \
#define GS_PRIVATE_INTERNAL(name) \
@interface name ## Internal : NSObject \
{ \
@public
/* Finish declaration of internal ivars.
*/
#define GS_END_INTERNAL(name) \
@public \
GS_##name##_IVARS \
} \
@end \
@implementation name ## Internal \
@ -80,29 +74,23 @@
#define GS_CREATE_INTERNAL(name) \
_internal = [name ## Internal new];
/* Create holder for internal ivars.
/* Destroy holder for internal ivars.
*/
#define GS_DESTROY_INTERNAL(name) \
DESTROY(_internal);
if (_internal != 0) DESTROY(_internal);
#undef internal
#define internal ((GSInternal*)_internal)
#undef GSIVar
#define GSIVar(X,Y) (((GSInternal*)(X->_internal))->Y)
#else /* !__has_feature(objc_nonfragile_abi) */
#else /* GS_NON_FRAGILE */
/* We have support for non-fragile ivars
*/
#define GS_BEGIN_INTERNAL(name) @interface name () {
#define GS_PRIVATE_INTERNAL(name)
/* Finish declaration of internal ivars.
*/
#define GS_END_INTERNAL(name) } @end
/* Create holder for internal ivars (nothing to do).
*/
#define GS_CREATE_INTERNAL(name)
#define GS_DESTROY_INTERNAL(name)
@ -114,6 +102,6 @@ DESTROY(_internal);
#undef GSIVar
#define GSIVar(X,Y) ((X)->Y)
#endif /* !__has_feature(objc_nonfragile_abi) */
#endif /* GS_NON_FRAGILE */