argstr interpolation for tuples is not the same as lists

[effigies]

xref nipype/pydra-mrtrix3#1 (comment)

[ghisvail]

I am having a similar issue with FreeSurfer's long option for recon-all whereby the expected format is a tuple of strings:

recon-all -long <tpNid> <templateid> -all

I'd expect to just be able to declare it as:

{
    "longitudinal",
    Tuple[str, str],
    {
        "help_string": "longitudinal processing scheme",
        "argstr": "-long",
    }
}

But it's getting interpolated as -long (tpNid, templateid).

I don't think using a list is the right solution here, since we want to constrain both the number of arguments (2) and their respective types (both string).

[ghisvail]

An alternative could be:

[
    {
        "longitudinal_timepoint_id",
        str,
        {
            "help_string": "longitudinal timepoint identifier",
            "argstr": "-long {longitudinal_timepoint_id} {longitudinal_template_id}",
            "requires": ["longitudinal_template_id"]
         },
    },
    {
         "longitudinal_template_id",
         str,
         {
             "help_string": "longitudinal template identifier",
             "argstr": None,  # handled by longitudinal_timepoint_id
             "requires": ["longitudinal_timepoint_id"],
         },
    },
]

which produces the expected output, but I am not familiar enough with pydra yet to figure out whether this is legit or a hack 😅

[tclose]

should be addressed in #801