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b04641a6a8
git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@32501 72102866-910b-0410-8b05-ffd578937521
141 lines
4.7 KiB
Objective-C
141 lines
4.7 KiB
Objective-C
/* GSInternal
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Copyright (C) 2009 Free Software Foundation, Inc.
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Written by: Richard Frith-Macdonald <rfm@gnu.org>
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This file is part of the GNUstep Base Library.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free
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Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02111 USA.
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*/
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/* This file defines macros for managing internal (hidden) instance variables
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* of a public class so that users of the public class don't need to recompile
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* their code when the class implementation is changed in new versions of the
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* library.
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*
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* The public class MUST declare its instance variables (after any public
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* instance variables which are part of the unchanging public API) using
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* code of the form:
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* #if GS_NONFRAGILE
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* # if defined(GS_X_IVARS)
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* @public GS_X_IVARS;
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* # endif
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* #else
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* @private id _internal GS_UNUSED_IVAR;
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* #endif
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*
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* In the non fragile case, this means that the public header has nothing
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* visible, but the ivars defined in GS_X_IVARS are visible within the
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* implementation.
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*
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* In the fragile case, the '_internal' instance variable is visible in the
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* public header, but as an opaque private instance variable, while macros
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* from this file allow the actual memory to be accessed either as a private
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* class. The use of a private class rather than simple heap memory is
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* necessary for garbage collection... the runtime is able to ensure that
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* garbage collection works properly for the instance variables in the
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* private class.
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*
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* Before including the header file containing the public class declaration,
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* you must define GS_X_IVARS (where X is the class name) to be the
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* list of actual instance variable declarations for the class.
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*
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* Before including this file, you must define 'GSInternal' to be the name
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* of your public class with * 'Internal' appended.
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* eg. if your class is called 'MyClass' then use the following define:
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* #define GSInternal MyClassInternal
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*
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* After including this file you can use the GS_PRIVATE_INTERNAL() macro
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* to declare the private subclass used to hold real instance variables.
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* The argument to this macro is the public class name (the GS_X_IVARS
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* list must also be defined).
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*
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* You use GS_CREATE_INTERNAL() in your intialiser to create the object
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* holding the internal instance variables, and GS_DESTROY_INTERNAL() to
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* get rid of that object in your -dealloc method.
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* You use GS_COPY_INTERNAL() in your implementations of -copyWithZone:
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* and -mutableCopyWithZone: in order to get the default copying behavior
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* for the internal class (a single copy of all the instance variables).
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*
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* Instance variables are referenced using the 'internal->ivar' suntax or
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* the GSIV(classname,object,ivar) macro.
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*
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*/
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#if !GS_NONFRAGILE
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/* Code for when we don't have non-fragile instance variables
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*/
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/* Start declaration of internal ivars.
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*/
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#define GS_PRIVATE_INTERNAL(name) \
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@interface name ## Internal : NSObject \
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{ \
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@public \
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GS_##name##_IVARS; \
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} \
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@end \
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@implementation name ## Internal \
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@end
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/* Create holder for internal ivars.
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*/
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#define GS_CREATE_INTERNAL(name) \
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_internal = [name ## Internal new];
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/* Destroy holder for internal ivars.
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*/
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#define GS_DESTROY_INTERNAL(name) \
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if (nil != _internal) {[_internal release]; _internal = nil; }
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/* Create a new copy of the current object's internal class and place
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* it in the destination instance. This poduces a bitwise copy, and you
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* may wish to perform further action to deepen the copy after using this
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* macro.
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* Use this only where D is a new copy of the current instance.
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*/
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#define GS_COPY_INTERNAL(D,Z) (D)->_internal = NSCopyObject(_internal, 0, (Z));
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#undef internal
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#define internal ((GSInternal*)_internal)
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#undef GSIVar
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#define GSIVar(X,Y) (((GSInternal*)((X)->_internal))->Y)
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#else /* GS_NONFRAGILE */
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/* We have support for non-fragile ivars
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*/
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#define GS_PRIVATE_INTERNAL(name)
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#define GS_CREATE_INTERNAL(name)
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#define GS_DESTROY_INTERNAL(name)
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#define GS_COPY_INTERNAL(D,Z)
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/* Define constant to reference internal ivars.
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*/
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#undef internal
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#define internal self
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#undef GSIVar
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#define GSIVar(X,Y) ((X)->Y)
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#endif /* GS_NONFRAGILE */
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