[Scons-dev] Scanners

[TOM TANNER (BLOOMBERG/ LONDON)]

I was having a look at why my build was potentially slow, and I noticed that my perl scanner was being called multiple times for the same file.

The only reason I can think of for this is that the environments are different (they have a different ID), but they are only different for reasons that aren't going to affect the perl script.

One of my problems with performance is possibly due to the number of environment clones I have, partly due to the port from an existing build system, and partly because from (painful) experience in other somewhat similar situations, it's safest to clone the environment before calling an SConscript.

I'm in somewhat of an uncomfy position here. I could rewrite substantial portions of my script to avoid cloning the environment for individual objects, and rely instead on passing lists of keywords to individual builders, but it'd make the script more difficult to understand and maybe less stable. And I don't know how much effect it would have.