| // Copyright 2014 The Chromium OS Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef LIBCHROMEOS_CHROMEOS_CHROMEOS_EXPORT_H_ |
| #define LIBCHROMEOS_CHROMEOS_CHROMEOS_EXPORT_H_ |
| |
| // Use CHROMEOS_EXPORT attribute to decorate your classes, methods and variables |
| // that need to be exported out of libchromeos. By default, any symbol not |
| // explicitly marked with CHROMEOS_EXPORT attribute is not exported. |
| |
| // Put CHROMEOS_EXPORT in front of methods or variables and in between the |
| // class and the tag name: |
| /* |
| |
| CHROMEOS_EXPORT void foo(); |
| |
| class CHROMEOS_EXPORT Bar { |
| public: |
| void baz(); // Exported since it is a member of an exported class. |
| }; |
| |
| */ |
| |
| // Exporting a class automatically exports all of its members. However there are |
| // no export entries for non-static member variables since they are not accessed |
| // directly, but rather through "this" pointer. Class methods, type information, |
| // virtual table (if any), and static member variables are exported. |
| |
| // Finally, template functions and template members of a class may not be |
| // inlined by the compiler automatically and the out-of-line version will not |
| // be exported and fail to link. Marking those inline explicitly might help. |
| // Alternatively, exporting specific instantiation of the template could be |
| // used with "extern template" and combining this with CHROMEOS_EXPORT. |
| #define CHROMEOS_EXPORT __attribute__((__visibility__("default"))) |
| |
| // On occasion you might need to disable exporting a particular symbol if |
| // you don't want the clients to see it. For example, you can explicitly |
| // hide a member of an exported class: |
| /* |
| |
| class CHROMEOS_EXPORT Foo { |
| public: |
| void bar(); // Exported since it is a member of an exported class. |
| |
| private: |
| CHROMEOS_PRIVATE void baz(); // Explicitly removed from export table. |
| }; |
| |
| */ |
| |
| // Note that even though a class may have a private member it doesn't mean |
| // that it must not be exported, since the compiler might still need it. |
| // For example, an inline public method calling a private method will not link |
| // if that private method is not exported. |
| // So be careful with hiding members if you don't want to deal with obscure |
| // linker errors. |
| #define CHROMEOS_PRIVATE __attribute__((__visibility__("hidden"))) |
| |
| #endif // LIBCHROMEOS_CHROMEOS_CHROMEOS_EXPORT_H_ |