Defining a symbolic syntax for referring to assignment targets

[blhsing (Ben Hsing)]

@ncoghlan

__target_text__ could replace @'' for both identifier assignment and tuple assignment ( __target_name__ wouldn’t match the latter use case)

Sounds good indeed. With the name __target_text__ we wouldn’t have to worry about a plural form.

I doubt you could reasonably use that form to map function parameters to local variables of the same name, though.

I don’t see why not. We can name the new keyword that forwards local variables to function parameters of the same names, __same__. The compiler with access to AST can clearly tell which keyword argument a ast.Same node belongs to and produces bytecode that loads the local variable of that name for the argument accordingly:

call_with_local_args(some_target=__same__)

This is really a completely separate proposal from the assignment target placeholder proposal though, and should be discussed about in a separate thread (perhaps in the PEP-736 thread, in which I have now made a post).

@ncoghlan

The __target__ dunder idea is interesting, as it doesn’t provide brevity gains in most cases, but does provide the benefit of avoiding repeated evaluation.

I suspect code that assigns to identifiers would continue to be better off just using the target identifier directly, but attribute access, subscripting, slicing, and tuple assignment could still see some utility.

Yeah the loss of brevity does take away the utility of this idea in cases of a single identifier, particularly as an alternative to PEP-736, where parameter names are always single identifiers.

I agree that we should focus more on its utility for more complex assignment targets.