How to build in different environments with SCons? - build

Question

I just discovered SCons, a great build tool.
I need to build my project in multiple environments, i.e. with different library paths and include paths depending on the machine.
Since SConstruct has all of Python available, I can imagine various ways to accomplish this. One possibility would be to have a single SConstruct script and instantiate multiple Environment objects.
envFoo = Environment()
envFoo.Append(CPPPATH = [...])
envBar = Environment()
envBar.Append(CPPPATH = [...])
Then select one of these Environment objects somehow, possibly with a command line parameter to scons.
A question for experienced scons users: Is this the way to go? What is the most convenient way of doing this?

Answer 1

This would definitely work, and would probably be a good solution for simpler situations. I have a more complex situation where I actually create an EnvironmentFactory using Python classes, something like this:
env = EnvironmentFactory.createEnv(cmdLineArgs)
Another useful SCons tool would be to "automatically" populate the Environment from the command line options using the ParseFlags(), ParseConfig(), and MergeFlags() as described in this chapter.

Answer 2

You could do this
envSelect = ARGUMENTS.get('env', "default")
if envSelect == "default":
env = Environment()
elif envSelect == "env2":
env = Environment(whatever you want to do here)
elif envSelect == "env3":
env = Environment(whatever you want to do here)
else:
env = Environment(whatever you want to do here)
With the ARGUMENTS.get you specify a default when you just run the command scons
or else you you do scons env=env2 hope this answers your question
EDIT : here's a snippet from a project I'm working on where I want to determine the os when scons runs
import sys
import os
import glob
import subprocess
#Find the host Operating System
platform = sys.platform
if platform != "win32":
env = Environment()
else:
#Specify to compile in 32-bit mode for Visual Studio
#This is needed as Qt libraries on Windows for Visual
#Studio are 32-bit only
env = Environment(TARGET_ARCH = 'x86')
#Get Qt directory as scons argument or use default setting
if platform != "win32":
qtDir = ARGUMENTS.get('qt', '/usr/local/Trolltech/Qt-4.8.4/')
else:
qtDir = ARGUMENTS.get('qt', 'C:\\Qt\\4.8.4\\')