Disucssion about nipype wrapping

[denisri]

In Capsul v2, nipype interfaces were wrapped in a capsul Process like this:

• all inputs were exported as input parameters
• all outputs were exportes as output parameters, but with a leading underscore in their name (ie main_output became _main_output) in order to avoid overlaps, because some interfaces may have the same parameter in both inputs and outputs - at least I guess this was the initial reason for this prefix (?)

However in capsul v3, fields are apparently not allowed to begin with an underscore. When we do it we see the message:

/casa/host/build/python/soma/controller/controller.py:195: RuntimeWarning: fields may not start with an underscore, ignoring "_inskull_mask_file"

So what should we do about that ?

1. use another prefix/suffix ?
2. use the "real" output names, and when a parameter happens to be both in inputs and outputs, do something else 2.1.rename it, 2.2. or make it an "input/output" parameter, for which we currently don't have a notion for, nor a representation in GUIs or pipeline graphs, links, etc.

In any case we would have to modify all existing processes/pipelines using nipype interfaces, because all their output parameters would change names.

[sapetnioc]

If Nipype allows to have two different values, we cannot choose 2.2. Moreover this is the more complex solution to implement. I would choose a 2.3 very close to 2.1. If two parameters with the same name are present in input and output then we rename both. For instance, main_output would become main_output_i and main_output_o. That way, user have to add a suffix (coul be a prefix) even for input parameter so he knows that there are two values for this one.

[denisri]

Why not. OK.