We stick this in our SConstruct:
1 def print_config(msg, two_dee_iterable):
2 # this function is handy and can be used for other configuration-printing tasks
3 print
4 print msg
5 print
6 for key, val in two_dee_iterable:
7 print " %-20s %s" % (key, val)
8 print
9
10 def config_h_build(target, source, env):
11
12 config_h_defines = {
13 # this is where you put all of your custom configuration values
14 "install_prefix": prefix_variable_fed_by_user,
15 "version_str": "1.0",
16 "debug": debug # this is an int. 1 for true, 0 for false
17 }
18
19 config_h_defines["foo"] = "hey look i added something else"
20
21 print_config("Generating config.h with the following settings:",
22 config_h_defines.items())
23
24 for a_target, a_source in zip(target, source):
25 config_h = file(str(a_target), "w")
26 config_h_in = file(str(a_source), "r")
27 config_h.write(config_h_in.read() % config_h_defines)
28 config_h_in.close()
29 config_h.close()
If you want to get values directly from your environment you can set config_h_defines to env.Dictionary():
1 def config_h_build(target, source, env):
2
3 config_h_defines = env.Dictionary()
4
5 print_config("Generating config.h with the following settings:",
6 config_h_defines.items())
7
8 for a_target, a_source in zip(target, source):
9 config_h = file(str(a_target), "w")
10 config_h_in = file(str(a_source), "r")
11 config_h.write(config_h_in.read() % config_h_defines)
12 config_h_in.close()
13 config_h.close()
And we call it like this:
1 env.AlwaysBuild(env.Command('config.h', 'config.h.in', config_h_build))
And of course here is our mocked-up config.h.in:
#define INSTALL_PREFIX "%(install_prefix)s" #define VERSION_STR "%(version_str)s" #define FOO "%(foo)s" #if %(debug)d #define YES_THIS_IS_A_DEBUG_BUILD 1 #else #define NDEBUG 1 #endif
This would generate the following config.h. We assume that the prefix was set to /usr/local and that it is *not* a debug build.
#define INSTALL_PREFIX "/usr/local" #define VERSION_STR "1.0" #define FOO "hey look i added something else" #if 0 #define YES_THIS_IS_A_DEBUG_BUILD 1 #else #define NDEBUG 1 #endif
The whole sequence of:
#if %(blah)d #define WHATEVER #endif
Is kind of ugly, I'm pretty sure you could also do:
#define WHATEVER %(blah)d
and then in your code, check for it by doing #if WHATEVER, instead of #ifdef WHATEVER.