Allow implicit multiline chaining without backslash (or parentheses) when using Builder pattern in GDScript

[ElvisVilla]

Hi, im working on a declarative UI for Godot Engine inspired in SwiftUI. Im using Builder pattern and Factory Methods to handle Control Node creation to enable a sintax similar to what Tween does, like this:

body = VBox([

        Label("Hello World")
            .fontSize(78),

        Button("Click Me")
            .onPressed(func(): print("Clicked!"))

    ]) \ # multiline chaining requirement
    .spacing(10) \ # here too
    .background(Color.BLACK.lightened(0.2), 10)

This is an odd sintax at the end, seems like for the Label and the Button doing the multiline chain is possible because the ',' separator defines the end of the expresion.

It is posible to enclose (VBox) in parentesis and this can be overpass but this is easily to forget and easily to delete and prone to errors, this hugely affect the usability of fluent API by method chaining in Godot.

I have also found that it is posible to do line breaks with ternary expresion in Godot, and I wonder if its posible to enable this for Builder pattern. Im not versed my self in Lenguage development, i was doing some chat with Claude about this, to see how to write this discussion and Claude gave me this :

Scope of Change
The proposal would apply to method chaining contexts where:

A line ends with a method call that returns self or the same type
The next line starts with a dot (.)
The context is inside parentheses, brackets, or function blocks

Grammar Rules:
# Rule: If line ends with method_call() and next line starts with .method()
# Then: treat as continuation without requiring backslash

expression_chain:
    | primary_expression
    | expression_chain DOT method_call
    | expression_chain DOT method_call NEWLINE DOT method_call  # NEW RULE

This could open the posibility to do this

# no backslash required '\'
var tween = create_tween()
    .set_ease(Tween.EASE_OUT)
    .set_trans(Tween.TRANS_CUBIC) 
    .parallel()
    .tween_property(node, "position", target_pos, 1.0)

Enabling method chaining without backslash improves imensively the usability of method chaining in GDScript.

[Calinou]

• Related to Allow newlines after match condition commas without requiring backslashes at end of each line #2201.