Parameter Changes Not Reflected in Function Call

[Subham7201]

Hi Team,

This is how the DSL looks.

CallExpression:
    'call' '('calledStatement=[MethodMember:QualifiedName]')' '{' parameters+=ActualParameter '}'

ActualParameter:
    refMember=[Parameter:ID] '=' (value=Expression)?

If a document is being referenced from multiple places, and changes (such as adding or removing parameters) are made in the document from another location. I want these changes (e.g., adding/removing parameters) to automatically propagate wherever the document is being referenced, and for the changes to be initialized with default values.

For example, I have a call to document like this:
call ABC(a=10 b=13)

And the document looks like this:
private ABC(int a, int b, int c) {
}

However, when I modify the parameters of the ABC (e.g., adding a new parameter, say, 'c'), the changes don't get reflected.

What approach should I take to ensure that any changes to the document's parameters are immediately reflected in the call? Any advice or best practices would be greatly appreciated!

[msujew]

Hey @Subham7201,

In theory, you can listen to the DocumentBuilder#onDocumentPhase listener to see whether a document has changed and what its new AST is:

1. Identify all caller sides of the changed function.
2. Build text edits to add default values for the respective parameter.
3. Send those changes to the language client to be applied.

However, there are multiple reasons why this might be difficult and why I wouldn't recommend doing this at all:

1. Generally, language servers should be very selective about what changes they force the user to apply. I would at least add a setting that allows this behavior to turn on/off.
2. Identifying what exactly has changed after any text edit (i.e. after the user presses a keystroke) isn't trivial. But caching might help with that.
3. Applying a default value for users might lead to very unexpected behavior, as I would assume that the newly added parameter usually has some semantic meaning, and just adding a default to the caller side might lead to unexpected runtime results, given that users don't need to manually adjust all caller sides to fit the new API.
4. Does your language feature a type system with structural information (i.e. structs, classes, or similar)? What are the defaults for those?

[Subham7201]

Hey @msujew,

I’m considering adding a diagnostic to my document so that any changes are reflected during the build phase, where the document is referenced. Alternatively, I’m thinking about using refactoring to reflect these changes.

Which approach would be more effective?

[msujew]

The usual approach for this would be a validation that marks all callers of the function that don't use the correct amount of arguments. I would use that in your case as well.