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Diffstat (limited to 'doc/user/misc.xml')
| -rw-r--r-- | doc/user/misc.xml | 57 |
1 files changed, 53 insertions, 4 deletions
diff --git a/doc/user/misc.xml b/doc/user/misc.xml index ed96625..5ade6d3 100644 --- a/doc/user/misc.xml +++ b/doc/user/misc.xml @@ -21,7 +21,7 @@ <!-- - Copyright (c) 2001 - 2017 The SCons Foundation + Copyright (c) 2001 - 2019 The SCons Foundation Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the @@ -268,9 +268,9 @@ hello.c <scons_example name="misc_FindFile1a"> <file name="SConstruct" printme="1"> # one directory -print(FindFile('missing', '.')) +print("%s"%FindFile('missing', '.')) t = FindFile('exists', '.') -print(t.__class__, t) +print("%s %s"%(t.__class__, t)) </file> <file name="exists"> exists @@ -287,7 +287,7 @@ print(t.__class__, t) includes = [ '.', 'include', 'src/include'] headers = [ 'nonesuch.h', 'config.h', 'private.h', 'dist.h'] for hdr in headers: - print('%-12s' % ('%s:' % hdr), FindFile(hdr, includes)) + print('%-12s: %s'%(hdr, FindFile(hdr, includes))) </file> <file name="config.h"> exists @@ -625,4 +625,53 @@ env.Command('directory_build_info', </section> + <section> + <title>Virtual environments (virtualenvs)</title> + + <para> + + 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. + + </para> + + <para> + + 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. + + </para> + + <para> + This issue may be overcome by using <literal>--enable-virtualenv</literal> + option. The option automatically imports virtualenv-related environment + variables to all created construction environment <literal>env['ENV']</literal>, + and modifies SCons PATH appropriately to prefer virtualenv's executables. + Setting environment variable <literal>SCONS_ENABLE_VIRTUALENV=1</literal> + will have same effect. If virtualenv support is enabled system-vide + by the environment variable, it may be suppressed with + <literal>--ignore-virtualenv</literal> option. + </para> + + <para> + Inside of SConscript, a global function <literal>Virtualenv</literal> is + available. It returns a path to virtualenv's home directory, or + <literal>None</literal> if SCons is not running from virtualenv. Note, + that this function returns a path even if SCons is run from an + unactivated virtualenv. + </para> + + </section> + </chapter> |