Combining `requires` and `output_file_template` for a field

[ghisvail]

I am trying to combine the effects of requires and output_file_template but failed so far.

Here is my latest attempt:

@attrs.define(kw_only=True)
class MyShellSpec(pydra.specs.ShellSpec):
    mandatory_arg: str = attrs.field(
        metadata={"help_string": "mandatory arg", "mandatory": True}
    )

    enable_bar: bool  = attrs.field(
        metadata={"help_string": "optional support for bar", "argstr": "-a"}
    )

    output_arg: str = attrs.field(
        metadata={
            "help_string": "output arg",
            "argstr": "-o",
            "output_file_template": "{mandatory_arg}_foo",
        }
    )

    maybe_output_arg: str = attrs.field(
        metadata={
            "help_string": "output arg if optional arg provided",
            "argstr": "-m",
            "output_file_template": "{mandatory_arg}_bar",
            "requires": {"enable_bar"},
        }
    )  

where I would want maybe_output_arg to get a templated default value only if an optional argument is provided. The reasoning behind it is that the underlying executable generates additional files based on whether some optional parameters have been provided.

Assuming this is not feasible,

• Is this something we would want to allow?
• If not, what's the alternative pattern to achieve the same behavior?

Cheers, Ghis

EDIT: Fix typo in code snippet

[satra]

@ghisvail - i don't see optional_arg anywhere. perhaps there should at least be something that checks that variables in requires are present in the spec.

[ghisvail]

My bad, optional -> enable_bar

Le jeu. 9 févr. 2023, 20:48, Satrajit Ghosh @.***> a écrit :

@ghisvail https://github.com/ghisvail - i don't see optional_arg anywhere. perhaps there should at least be something that checks that variables in requires are present in the spec.

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[ghisvail]

perhaps there should at least be something that checks that variables in requires are present in the spec.

Indeed :sweat_smile:, this mistake was not intended but you're right requires should only reference a field present in the spec.

I fixed the code snippet.

[satra]

i would say this is likely a order of operations resolution problem in the spec processor. do you have the inclination to send a PR ?

[ghisvail]

do you have the inclination to send a PR ?

I can have a look