Virtualenv is a tool to create isolated Python environments. A python application (such as SCons) may be executed within an activated virtualenv. The activation of virtualenv modifies current environment by defining some virtualenv-specific variables and modifying search PATH, such that executables installed within virtualenv's home directory are preferred over the ones installed outside of it.
Normally, SCons uses hard-coded PATH when searching for external executables, so it always picks-up executables from these pre-defined locations. This applies also to python interpreter, which is invoked by some custom SCons tools or test suites. This means, when running SCons in a virtualenv, an eventual invocation of python interpreter from SCons script will most probably jump out of virtualenv and execute python executable found in hard-coded SCons PATH, not the one which is executing SCons. Some users may consider this as an inconsistency.
This issue may be overcome by using the
option. The option automatically imports virtualenv-related environment
variables to all created construction environment
and modifies SCons PATH appropriately to prefer virtualenv's executables.
Setting environment variable
will have same effect. If virtualenv support is enabled system-vide
by the environment variable, it may be suppressed with the
SConscript, a global function
available. It returns a path to virtualenv's home directory, or
None if scons is not running from virtualenv. Note
that this function returns a path even if scons is run from an