Enhance: add keyword semantics to PDB calls using defaults for missing args
Currently a PDB procedure has defaults for trailing args but a call must pass all args.
The enhancement is to let a PDB procedure be called with a prefix of its formal args, and GIMP would supply the formal defaults for missing actual args (like Python keyword args.) In other words, the GimpValueArray for the arguments could be shorter than usual.
The current use for defaults is only to initialize widgets when a control dialog is shown.
The benefit is to plugin author's. They could quickly prototype a call to a PDB procedure and defer till later tweaking the defaulted arguments (which are often controls to filters.)
I think this is easily implemented in one source code file, for function gimp_procedure_run().
Recent changes to ScriptFu mean that a Scheme call to the PDB with missing trailing arguments would go through with a warning.
This would not affect plugins in other languages, since, for a PDB call in a plugin, the interpreter and binding does not check the signature of the PDB procedure.