some cases of argname don't know how to deal

[wulidongdong]

Hi Devs,

I got some dumb questions when I using argname. I would like to know if the following two cases can be achieved:
First, I defined a class and three variables：

def test(a=None, b=None, c=None):
    return argname('b')

x = [[111]]
y = [[222]]
z = [x, y]

The first question is how to know when calling a function that one of the variables is a list.

That is, when I call it like this:
test(a=x,b=z,c=y)
I expect the return result of the current function to be
'[x,y]'
but the return result of the current function is
'z'
I tried to call
test(a=x,b=[x,y],c=y)
but it reports an error.

    498 source = argument_sources[farg_name]
    499 if isinstance(source, ast.AST):
--> 500     raise ImproperUseError(
    501         f"Argument {ast.dump(source)} is not a variable "
    502         "or an attribute."
    503     )
    505 if isinstance(farg_subscript, int) and not isinstance(source, tuple):
    506     raise ImproperUseError(
    507         f"`{farg_name}` is not a positional argument."
    508     )

ImproperUseError: Argument List(elts=[Name(id='x', ctx=Load()), Name(id='y', ctx=Load())], ctx=Load()) is not a variable or an attribute.

The second problem is that using argname and exec at the same time seems to report an error. For example, executing

test_str = 'test(a=x,b=z,c=y)'
exec(test_str)

will report an error:

    439 # Only do it when func_node are available
    440 if not func_node:
    441     # We can do something at bytecode level, when a single positional
    442     # argument passed to both functions (argname and the target function)
    443     # However, it's hard to ensure that there is only a single positional
    444     # arguments passed to the target function, at bytecode level.
--> 445     raise VarnameRetrievingError(
    446         "Cannot retrieve the node where the function is called."
    447     )
    449 func_node = reconstruct_func_node(func_node)
    451 if not func:

VarnameRetrievingError: Cannot retrieve the node where the function is called.

Can the above two problems be solved? Thank you for your time

[wulidongdong]

I have read other issues, it seems to be solved by wrapper.

from varname.helpers import Wrapper

def test(a=None, b=None, c=None):
    for i in b:
        print(i.name, i.value)

x = Wrapper([[111]])
y = Wrapper([[222]])
z = [x, y]
test(a=x,b=z,c=y) # x [[111]] y[[222]]

and exec can work!

test_str = 'test(a=x,b=z,c=y)'
exec(test_str) # x [[111]] y[[222]]

cool, although I do not know why it can work

[pwwang]

Remember that argname() gets what directly pass to the function. So test(a=x,b=z,c=y) is supposed to return 'z'. To get [x,y] for test(a=x,b=[x,y],c=y), you need:

def test(a=None, b=None, c=None):
    return argname('b', vars_only=False)

exec('test(a=x,b=[x,y],c=y)') won't work because we are not able to retrieve the source/AST at runtime.

---

The solution you posted later does not use the source/AST when test is called (because you don't call argname inside). If you did mean argname, then test(a=x,b=z,c=y) should return z. Anyway, it is a good solution if it meets your need.