It makes me sad that the PEP for the equivalent behaviour for function keyword arguments wasn’t accepted. It’s really common to see foo(bar=bar) and I think it’s not only cleaner but would help see subtle differences if that was foo(bar=) because it would make the cases where some arguments aren’t simply being passed through more obvious: foo(bar=, …, baaz=baaz.get_id()) avoids the most interesting detail being easily missed.
Do you know why? I didn't know of the fstring one either but I've thought to myself across many languages that a way to print the expression (or just varname in my head) with the result should exist.
Grammar changes, in particular things used everywhere like function invocations, have to be worth paying the price for changing/adding new rules. The benefits of fewer characters and more explicit intention weren't enough to outweigh the costs.
There were other considerations: Do linters prefer one syntax to another? Does the name refer to the parameter or the argument in tooling? Should users feel pressure to name local variables the same as the function's parameters? What about more shorthand for common cases like func(x=self.x, y=self.y)?
I personally did not like the func(x=, y=) syntax. I think their example of Ruby's func(x:, y:) would actually make more sense, since it's syntax that would read less like "x equals nothing", and more "this is special syntax for passing arguments".
Guess I will chime in for the dissent: there is already so much Python language. The more special gotchas that are added just for these minor wins is not worth it. In fact, if I ever saw a function that was foo(bar=) I would correct that to be explicit immediately. ‘import this’ and all that.
Said as a curmudgeon that has never used a walrus.
