inherit ActionConfigFile from _AppendAction for better compatible with shtab

[tshu-w]

I open a new issue to discuss it and close the original one #108.

shtab use option type to decide completion nargs format in this line, however ActionConfigFile doesn't inherit from any of OPTION_MULTI = _AppendAction, _AppendConstAction, _CountAction, should ActionConfigFile inherit from _AppendAction as it accept python cli.py --config config.yaml --confg config2.yaml?

[mauvilsa]

ActionConfigFile inheriting from _AppendAction would only make sense if somehow it could use part of that class's functionality, e.g. doing super().__init__(...) or super().__call__(...). But there is nothing that can be reused from that class. Adding it just so that shtab handles it in some particular way would be a hack and not a good programing practice. Therefore, I will not do this.

@tshu-w you have suggested doing this but gave no motivation for it. What does it do?

Something that wouldn't be a hack and potential addition in jsonargparse could be:

import shtab
from jsonargparse import ActionConfigFile
shtab.OPTION_MULTI = shtab.OPTION_MULTI + (ActionConfigFile,)

Though, I don't know if OPTION_MULTI can be considered stable and part of the public API of shtab. Would be better to have an explicit public function to register such things. @casperdcl a comment from you could be useful.

[tshu-w]

Adding it just so that shtab handles it in some particular way would be a hack and not a good programing practice. Therefore, I will not do this.

Thanks for you reply. I see.

@tshu-w you have suggested doing this but gave no motivation for it. What does it do?

I don't particularly understand what you mean. If I understand correctly, the reason I did this was so that shtab would generate the correct zsh completion function for LightningCLI, since --config takes multiple arguments, but now zsh no longer completes --config after entering it once.

Anyway I understand your idea, and also implemented it like the following way.

import shtab
from jsonargparse import ActionConfigFile
shtab.OPTION_MULTI = shtab.OPTION_MULTI + (ActionConfigFile,)

I don't think this is something jsonargparse needs to handle anymore, so I closed the issue and will talk to @casperdcl about OPTION_MULTI if needed.