nipy/nipype — pull request #393 by satra (2012-05-18 14:22:01+00:00)
Title: WIP: changing hashing behavior for some base traits

these are cases where an environment variable is set.

case 1. FSL
environment variable sets output type

case 2. FreeSurfer
environment variable sets subjects dir - although it seems like this will not be important, the timestamp hash of contents of a subjects dir could change.

case 3. ANTS/openmp processes
environment variable sets number of threads

currently we hash environment variables that are set by the user or in the cases above, set through a function on the base class.

the question really boils down to - how do we determine in which cases the environment variable is important (case 1) and where it's not (case 3) and where it may be important (case 2).

so i'm leaning towards not hashing environ - in all the cases above there is an input that needs to be set. for example, in ants we can not hash num_threads.

thoughts?