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| author | Lorry Tar Creator <lorry-tar-importer@baserock.org> | 2009-08-18 20:56:02 +0000 |
|---|---|---|
| committer | Lorry <lorry@roadtrain.codethink.co.uk> | 2012-09-25 16:59:08 +0000 |
| commit | 9f8a09ed743cedd9547bf0661d518647966ab114 (patch) | |
| tree | 9c7803d3b27a8ec22e91792ac7f7932efa128b20 /Examples/python/constants | |
| download | swig-tarball-master.tar.gz | |
Imported from /srv/lorry/lorry-area/swig-tarball/swig-1.3.40.tar.gz.HEADswig-1.3.40master
Diffstat (limited to 'Examples/python/constants')
| -rw-r--r-- | Examples/python/constants/Makefile | 20 | ||||
| -rw-r--r-- | Examples/python/constants/example.i | 27 | ||||
| -rw-r--r-- | Examples/python/constants/index.html | 67 | ||||
| -rw-r--r-- | Examples/python/constants/runme.py | 27 |
4 files changed, 141 insertions, 0 deletions
diff --git a/Examples/python/constants/Makefile b/Examples/python/constants/Makefile new file mode 100644 index 0000000..1420b4e --- /dev/null +++ b/Examples/python/constants/Makefile @@ -0,0 +1,20 @@ +TOP = ../.. +SWIG = $(TOP)/../preinst-swig +SRCS = +TARGET = example +INTERFACE = example.i + +all:: + $(MAKE) -f $(TOP)/Makefile SRCS='$(SRCS)' SWIG='$(SWIG)' \ + TARGET='$(TARGET)' INTERFACE='$(INTERFACE)' python + +static:: + $(MAKE) -f $(TOP)/Makefile SRCS='$(SRCS)' SWIG='$(SWIG)' \ + TARGET='mypython' INTERFACE='$(INTERFACE)' python_static + +clean:: + $(MAKE) -f $(TOP)/Makefile python_clean + rm -f $(TARGET).py + +check: all + $(MAKE) -f $(TOP)/Makefile python_run diff --git a/Examples/python/constants/example.i b/Examples/python/constants/example.i new file mode 100644 index 0000000..4f7b1a4 --- /dev/null +++ b/Examples/python/constants/example.i @@ -0,0 +1,27 @@ +/* File : example.i */ +%module example + +/* A few preprocessor macros */ + +#define ICONST 42 +#define FCONST 2.1828 +#define CCONST 'x' +#define CCONST2 '\n' +#define SCONST "Hello World" +#define SCONST2 "\"Hello World\"" + +/* This should work just fine */ +#define EXPR ICONST + 3*(FCONST) + +/* This shouldn't do anything */ +#define EXTERN extern + +/* Neither should this (BAR isn't defined) */ +#define FOO (ICONST + BAR) + +/* The following directives also produce constants */ + +%constant int iconst = 37; +%constant double fconst = 3.14; + + diff --git a/Examples/python/constants/index.html b/Examples/python/constants/index.html new file mode 100644 index 0000000..35cc0d7 --- /dev/null +++ b/Examples/python/constants/index.html @@ -0,0 +1,67 @@ +<html> +<head> +<title>SWIG:Examples:python:constants</title> +</head> + +<body bgcolor="#ffffff"> + +<tt>SWIG/Examples/python/constants/</tt> +<hr> + +<H2>Wrapping C Constants</H2> + +<p> +When SWIG encounters C preprocessor macros and C declarations that look like constants, +it creates Python variables with an identical value. Click <a href="example.i">here</a> +to see a SWIG interface with some constant declarations in it. + +<h2>Accessing Constants from Python</h2> + +Click <a href="example.py">here</a> to see a script that prints out the values +of the constants contained in the above file. + +<h2>Key points</h2> + +<ul> +<li>The values of preprocessor macros are converted into Python constants. +<li>Types are inferred by syntax (e.g., "3" is an integer and "3.5" is a float). +<li>Character constants such as 'x' are converted into Python strings. +<li>C string literals such as "Hello World" are converted into Python strings. +<li>Macros that are not fully defined are simply ignored. For example: +<blockquote> +<pre> +#define EXTERN extern +</pre> +</blockquote> +is ignored because SWIG has no idea what type of variable this would be. + +<p> +<li>Expressions are allowed provided that all of their components are defined. Otherwise, the constant is ignored. + +<li>Certain C declarations involving 'const' are also turned into Python constants. +<li>The Python variables that SWIG creates are not protected from modification. For example, +even if you had this: +<blockquote> +<pre> +#define FOO 73 +</pre> +</blockquote> +a user could come along in a script and type +<blockquote> +<pre> +example.FOO = 13 +</pre> +</blockquote> +Unfortunately, there's no easy way to prevent this. + +<p> +<li>The constants that appear in a SWIG interface file do not have to appear in any sort +of matching C source file since the creation of a constant does not require linkage +to a stored value (i.e., a value held in a C global variable or memory location). +</ul> + +<hr> + + +</body> +</html> diff --git a/Examples/python/constants/runme.py b/Examples/python/constants/runme.py new file mode 100644 index 0000000..8d25b87 --- /dev/null +++ b/Examples/python/constants/runme.py @@ -0,0 +1,27 @@ +# file: runme.py + +import example + +print "ICONST =", example.ICONST, "(should be 42)" +print "FCONST =", example.FCONST, "(should be 2.1828)" +print "CCONST =", example.CCONST, "(should be 'x')" +print "CCONST2 =", example.CCONST2, "(this should be on a new line)" +print "SCONST =", example.SCONST, "(should be 'Hello World')" +print "SCONST2 =", example.SCONST2, "(should be '\"Hello World\"')" +print "EXPR =", example.EXPR, "(should be 48.5484)" +print "iconst =", example.iconst, "(should be 37)" +print "fconst =", example.fconst, "(should be 3.14)" + +try: + print "EXTERN = ", example.EXTERN, "(Arg! This shouldn't print anything)" +except AttributeError: + print "EXTERN isn't defined (good)" + +try: + print "FOO = ", example.FOO, "(Arg! This shouldn't print anything)" +except AttributeError: + print "FOO isn't defined (good)" + + + + |