From 6f7255096462195be3ea812b4dcf9dbee6d08ef0 Mon Sep 17 00:00:00 2001 From: Sye van der Veen Date: Sun, 16 Mar 2014 15:49:18 -0400 Subject: Update comments to clarify benefits of script_env memoization --- src/engine/SCons/Tool/MSCommon/vc.py | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/src/engine/SCons/Tool/MSCommon/vc.py b/src/engine/SCons/Tool/MSCommon/vc.py index b5491b1..72e7c77 100644 --- a/src/engine/SCons/Tool/MSCommon/vc.py +++ b/src/engine/SCons/Tool/MSCommon/vc.py @@ -299,9 +299,12 @@ def reset_installed_vcs(): __INSTALLED_VCS_RUN = None # Running these batch files isn't cheap: most of the time spent in -# msvs.generate() is due to vcvars*.bat. In a build that keeps separate -# environments for debug and release, or perhaps builds against multiple -# MSVS versions at once, we can save a lot of time by caching the output. +# msvs.generate() is due to vcvars*.bat. In a build that uses "tools='msvs'" +# in multiple environments, for example: +# env1 = Environment(tools='msvs') +# env2 = Environment(tools='msvs') +# we can greatly improve the speed of the second and subsequent Environment +# (or Clone) calls by memoizing the environment variables set by vcvars*.bat. script_env_stdout_cache = {} def script_env(script, args=None): cache_key = (script, args) -- cgit v0.12