scons hierarchcal builds: propagating builders

Question

Hi All,

I need to be able to tune a construction environment so that I can either build a static or a shared objects in lower levels. Currently, I came up with the following approach:

top-level SConstruct:

if build_shared:
    env.Replace(ObjectBuilder = env.SharedObject)
    env.Replace(LibraryBuilder = env.SharedLibrary)
else:
    env.Replace(ObjectBuilder = env.StaticObject)
    env.Replace(LibraryBuilder = env.StaticLibrary)

and in lower-level SConstructs I invoke them by name:

env['ObjectBuilder']('foo.c')
env['LibraryBuilder']('lib', objects)

However, I'm not sure how sound this solution is. Is there a more straightforward/proper way to achieve the same functionality?

Thanks in advance.

Answer 1

If this is a user controllable option, you may want to use the AddOption, GetOption interfaces to control whether static or dynamic libraries are built. IMHO, that methodology doesn't seem too bad, but I've not seen many SCons scripts aside from my own.

Answer 2

The easiest way is to declare your own wrapper for env.Library() that simply passes its parameters to either env.StaticLibrary() or env.SharedLibrary().

Depending on whatever construction variable/scons option, you can have that wrapper alternate between the two.

def MyLibraryWrapper(self, *args, **kwargs):
  if self['BUILD_SHARED']:
    return self.SharedLibrary(*args, **kwargs)
  else:
    return self.StaticLibrary(*args, **kwargs)

env.SetDefault(BUILD_SHARED = False)
env.AddMethod(MyLibraryWrapper)

Make sure that snippet is your SConstruct, before any SConscript is parsed. To make it extra clean, create a tool in site_scons/site_tools and load it using env.Tool().