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git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@12108 626c5289-ae23-0410-ae9c-e8d60b6d4f22
55 lines
1.6 KiB
HTML
55 lines
1.6 KiB
HTML
<html>
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<title>SWIG:Examples:go:constants</title>
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</head>
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<body bgcolor="#ffffff">
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<tt>SWIG/Examples/go/constants/</tt>
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<hr>
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<H2>Wrapping C Constants</H2>
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<p>
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When SWIG encounters C preprocessor macros and C declarations that
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look like constants, it creates a Go constant with an identical value.
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Click <a href="example.i">here</a> to see a SWIG interface with some
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constant declarations in it.
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<h2>Accessing Constants from Go</h2>
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Click <a href="../../../Doc/Manual/Go.html#go_constants">here</a> for
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the section on constants in the SWIG and Go documentation.
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<p>
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Click <a href="runme.go">here</a> to see a Go program that prints out
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the values of the constants contained in the above file.</p>
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<h2>Key points</h2>
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<ul>
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<li>All names are capitalized to make them visible.
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<li>The values of preprocessor macros are converted into Go constants.
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<li>C string literals such as "Hello World" are converted into Go strings.
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<li>Macros that are not fully defined are simply ignored. For example:
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<blockquote>
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<pre>
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#define EXTERN extern
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</pre>
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</blockquote>
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is ignored because SWIG has no idea what type of variable this would be.
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<p>
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<li>Expressions are allowed provided that all of their components are
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defined. Otherwise, the constant is ignored.
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<li>Certain C declarations involving 'const' are also turned into Go
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constants.
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<li>The constants that appear in a SWIG interface file do not have to
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appear in any sort of matching C source file since the creation of a
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constant does not require linkage to a stored value (i.e., a value
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held in a C global variable or memory location).
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</ul>
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<hr>
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</body>
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</html>
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