How to get all 'nonlocals' variables?

Python Help
1

Background: I came across PEP 736 (which I haven’t finished reading it yet) and I was messing around trying to “reproduce” the effect.

I have defined a function lazyArg() as follows:

def lazyArg(func):
	# Assuming Ellipsis will never be an argument of `func`
	def new_func(*args, **kwargs):
		for k, v in kwargs.items():
			if isinstance(v, type(Ellipsis)):
				kwargs[k] = globals()[k]
		func(*args, **kwargs)
	return new_func

such that I can do things like this:

@lazyArg
def say(name, msg, target=None):
	if target is None:
		print(f"{name} says: {msg}")
	else:
		print(f"{name} says to {target}: {msg}")


name = 'Foo'
msg = 'Hello World!'
target = 'Bar'

say(
	name=...,
	msg=...,
	target=...,
) # Foo says to Bar: Hello World!

Of course, as I used globals() in lazyArg(), this won’t work:

def main():
	name = 'Foo'
	msg = 'Hello World!'
	target = 'Bar'
	
	say(
		name=...,
		msg=...,
		target=...,
	)


main()  # KeyError

My question is, how to obtain all the ‘outter scope’ variable, just like doing the ‘nonlocals’ version of globals()?

2

You mean you want get the local variables of the location from where the call happened?

Use sys._getframe(1).f_locals, or something like it.

1 Like
3

I am not sure what you are asking, but function objects have an attribute (use dir(f)) for nonlocals.

4

I was trying to do something like this:

def main():
    x = 1
    f(x=Ellipsis)

To let f() replace the Ellipsis argument with 1, f() would need to access all variables under main(). globals() can’t do that, neither can locals(), so I am looking for some way to do that, something like a nonlocals()

5

Oh, wow, that’s right, this does exactly what OP wants.

def lazyArg(func):
	import sys
	# Assuming Ellipsis will never be an argument of `func`
	def new_func(*args, **kwargs):
		for k, v in kwargs.items():
			if isinstance(v, type(Ellipsis)):
				kwargs[k] = sys._getframe(1).f_locals[k]  # <<--
		func(*args, **kwargs)
	return new_func
1 Like
6

Just be aware, sys._getframe has an underscore for a reason. It is internal details, and can change at any time; it’s only in CPython, not part of other Python implementations (or if it is, it can be completely different); and anything you do that depends on it could break at any time.

But, with all those caveats said: Go have fun with it!

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