89 lines
3.4 KiB
C
89 lines
3.4 KiB
C
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//
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// GTMMethodCheck.h
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//
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// Copyright 2006-2008 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not
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// use this file except in compliance with the License. You may obtain a copy
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// of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations under
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// the License.
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//
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#import <Foundation/Foundation.h>
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#import <stdio.h>
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#import <sysexits.h>
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/// A macro for enforcing debug time checks to make sure all required methods are linked in
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//
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// When using categories, it can be very easy to forget to include the
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// implementation of a category.
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// Let's say you had a class foo that depended on method bar of class baz, and
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// method bar was implemented as a member of a category.
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// You could add the following code:
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// @implementation foo
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// GTM_METHOD_CHECK(baz, bar)
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// @end
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// and the code would check to make sure baz was implemented just before main
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// was called. This works for both dynamic libraries, and executables.
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//
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// Classes (or one of their superclasses) being checked must conform to the
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// NSObject protocol. We will check this, and spit out a warning if a class does
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// not conform to NSObject.
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//
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// This is not compiled into release builds.
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#ifdef DEBUG
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#ifdef __cplusplus
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extern "C" {
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#endif
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// If you get an error for GTMMethodCheckMethodChecker not being defined,
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// you need to link in GTMMethodCheck.m. We keep it hidden so that we can have
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// it living in several separate images without conflict.
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// Functions with the ((constructor)) attribute are called after all +loads
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// have been called. See "Initializing Objective-C Classes" in
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// http://developer.apple.com/documentation/DeveloperTools/Conceptual/DynamicLibraries/Articles/DynamicLibraryDesignGuidelines.html#//apple_ref/doc/uid/TP40002013-DontLinkElementID_20
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__attribute__ ((constructor, visibility("hidden"))) void GTMMethodCheckMethodChecker(void);
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#ifdef __cplusplus
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};
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#endif
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// This is the "magic".
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// A) we need a multi layer define here so that the stupid preprocessor
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// expands __LINE__ out the way we want it. We need LINE so that each of
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// out GTM_METHOD_CHECKs generates a unique class method for the class.
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#define GTM_METHOD_CHECK(class, method) GTM_METHOD_CHECK_INNER(class, method, __LINE__)
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#define GTM_METHOD_CHECK_INNER(class, method, line) GTM_METHOD_CHECK_INNER_INNER(class, method, line)
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// B) Create up a class method called xxGMethodCheckMethod+class+line that the
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// GTMMethodCheckMethodChecker function can look for and call. We
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// look for GTMMethodCheckMethodChecker to enforce linkage of
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// GTMMethodCheck.m.
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#define GTM_METHOD_CHECK_INNER_INNER(class, method, line) \
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+ (void)xxGTMMethodCheckMethod ## class ## line { \
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void (*addr)() = GTMMethodCheckMethodChecker; \
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if (addr && ![class instancesRespondToSelector:@selector(method)] \
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&& ![class respondsToSelector:@selector(method)]) { \
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fprintf(stderr, "%s:%d: error: We need method '%s' to be linked in for class '%s'\n", \
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__FILE__, line, #method, #class); \
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exit(EX_SOFTWARE); \
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} \
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}
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#else // !DEBUG
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// Do nothing in release.
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#define GTM_METHOD_CHECK(class, method)
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#endif // DEBUG
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