Feature request: Set a default completion function

[albers]

In my experience, not many flags actually require completion of files.

Some have dynamic completions, but a great deal of them take free-form string parameters where no completion can be offered.
Unfortunately, the default completion for a flag with no completion function in Cobra is file completion.
This forces me to register a cobra.NoFileCompletions for each flag of that category.

As an example, completion for docker run has 56 flags where no meaningful FlagCompletionFunc exists.
In a first attempt, I registered 56 handlers with cmd.RegisterFlagCompletionFunc("flag-name", cobra.NoFileCompletions) just to silence their file completion.
Following a hint of @thaJeztah, I replaced them with a programmatically installed default handler, see here.

I would very much welcome a solution in Cobra, where I can set a default handler on command level, something like

cmd.CompletionOptions.DefaultCompHandler = cobra.NoFileCompletions

With this feature, I'd only have to define the completion functions for flags that actually have meaningful completions.

/cc @thaJeztah

[marckhouzam]

I agree. I regret making file completion the default behaviour; in retrospect, no completion should have been the default. But now we are stuck with this default behaviour. Adding an option to change the default completion sounds like a good idea.

[thaJeztah]

Thanks! And thanks for opening @albers - were you planning to work on this?

I just recalled I had that other issue with custom flags that can be set multiple times, but were not detected for completion (multiple times); I just pushed a PR with some changes In had stashed locally;

• completion: improve detection for flags that accept multiple values #2210

[albers]

@thaJeztah I will give it a try.

[albers]

@marckhouzam File completion was an obvious choice though, as it is exactly what bash completion resorts to in case no completion is defined.