@executable_path in Mac OSX, understanding of @load_path and @rpath

This article is reproduced from: https://wincent.com/wiki/@executable_path,[email protected][email protected]. Personally feel that writing is very good, concise and clear.

Absolute paths

Useful for frameworks installed in shared locations. Example:

• Install Path:/Library/Frameworks/Foo.framework/Versions/A/Foo

@executable_path

Useful for frameworks embedded inside applications, because it allows your to specify the location of the framework Relativ E to the application ' s executable:

• Install Path:@executable_path/../Frameworks/Foo.framework/Versions/A/Foo
• Application Location:/Applications/Foo.app
• Executable Path:/Applications/Foo.app/Contents/MacOS
• Framework Location:/Applications/Foo.app/Contents/Frameworks/Foo.framework
• Linker puts all this together to figure out the framework binary can is found at:/Applications/Foo.app/Contents/MacOS/../Frameworks/Foo.framework/Versions/A/Foo

@loader_path

Available From mac OS x 10.4 tiger onwards; useful for frameworks embedded inside Plug-ins, Because it allows specify the location of the framework relative to the plug-in ' s code (remember, Plug-ins Actually know where they is going to being installed, relative to the application, so knowing  @executable_path  DOESN ' t help us in this case):

• Install path:  @loader_path/.. /frameworks/foo.framework/versions/a/foo
• application location:  /applications/foo.app
• plug-in location:  /library/application support/foo/plug-ins/bar.bundle
• executable path:  /applications/foo.app/contents/macos
• Loader path:  /library/application Support/foo/plug-ins/bar.bundle/contents/macos
• Framework location:  /library/application support/foo/plug-ins/bar.bundle/contents/frameworks/ Foo.framework
• Linker puts all this together to figure out the the framework binary can is found At:/library/application support/foo/plug-ins/bar.bundle/contents/macos/. /frameworks/foo.framework/versions/a/foo

Note that if the ' loader ' is an application rather than a plug-in, the @loader_path ends up being equivalent to @executable_path .

@rpath

New in Mac OS X 10.5 Leopard is @rpath . Key points:

• @rpathInstructs the dynamic linker to search a list of paths in order to locate the framework
• Critically, this list was embedded in the loading application
• This means. A single framework @rpath/Foo.framework/Versions/A/Foo with can being made to work in a number of different ways; Ely no longer limited by the choice of specifying your "install path" using either @executable_path or@loader_path
• The down side:you now has to pass additional linker flags when building the host application (eg. -rpath @executable_path/../Frameworks or /Library/Frameworks ; note th At specifying both would cause the dynamic linker to try looking in both locations)

Sources

• Nice overview:http://www.mikeash.com/pyblog/friday-qa-2009-11-06-linking-and-install-names.html
• Docs for using Pfiddlesoft frameworks (I-ve never used these, but the manual itself makes some nice general points about u Sing frameworks): Http://pfiddlesoft.com/frameworks/downloads/Assistive_Application_Programming_Guide.pdf

@executable_path in Mac OSX, understanding of @load_path and @rpath