When calling method with more than N arguments, prompt to complete with named arguments

[matthughes]

Is your feature request related to a problem? Please describe.

When calling a method with a large number of arguments, it's sometimes hard to remember the names, types, and order of the arguments. Code completion works up to a point but 1) if you introduce a small error, you lose it and 2) the autocomplete tends to slow things down as it has to work after each argument.

Consider the following case class:

case class Foo(
  arg1: Int,
  arg2: String,
  arg3: Baz,
  // 12 more
  arg15: Bar
)

Describe the solution you'd like

If I invoke a method or case class with more than N arguments, I want a smart completion option ("complete with named arguments) that inserts this (using example from above):

case class Foo(
  arg1 = ???, // Int
  arg2 = ???, // String
  arg3 = ???, // Baz
  // 12 more
  arg15 = ??? // Bar
)

This gets me compiling code (in most cases) directly at the call site that I can now edit and fill in the holes as I'm ready to. For large methods like this, I often use the "use named arguments" function anyway but only after I've successfully gathered all the arguments.

Describe alternatives you've considered

I often will pull up a split pane in VsCode with the method I'm calling so I can see the arguments required without auto-complete coming up and disappearing.

Another option would be something like "show function in split pane". I guess the problem is the way auto-complete pop-overs work in VsCode. Because they are not sticky it's hard to see your place in a sea of more than a few method arguments.

Additional context

No response

Search terms

autocomplete arguments

[tgodzik]

Thanks for reporting! There is actually an existing completion, but it seems to be hidden now more than before

Screencast from 24.06.2024 14:51:05.webm

I am not sure how to make it visible, but maybe we could make it a code action instead? Or optionally as suggested, show it more prominent when it's a lot of arguments :thinking:

[tgodzik]

And it will try to input the values, so might not be perfect for your use case

[matthughes]

omg that's awesome! So you just type the word auto? Is this documented somewhere? Definitely +100 for making it a code action or something cause I never would have discovered this.

[tgodzik]

I don't think that was ever properly documented, but also we weren't sure of the UX here, so we need to fix that.

https://scalameta.org/metals/blog/2019/09/12/thorium/#add-auto-fill-option-to-case-classes <- that's from release notes