Question

Is it possible to get the name of the passed parameter in Python?

Specifically, I want to be able to do this:

def a(name):
    print "the actual passed parameter is %s" %(???)

What it solves?

So if I need to distribute coins in bags and baskets, say bag_list and basket_list, I need not send an explicit identifier saying ‘bag’ or ‘basket’

Which is how I’ve currently worked around it. I’m currently using a (global) dictionary for this purpose-

ID = {'bag': bag_list, 'basket': basket_list}

def a(name, id):
   dist_list = ID[id]

It also boils down to converting a variable name to string because the desired behavior can also be modeled as:

def a(name):
    name = ???get variable name as string magically???
    if name.startswith('bag'): 
         dist_list = ID['bag']
    else:
         dist_list = ID['basket']

The re-modeled question has been answered comprehensively in https://stackoverflow.com/a/9121991/1397945 but I’m re-posting this

• just in case there have been some modifications &
• whether it is possible to do this in other scripting languages like Perl or Tcl.
• More so, in case the two ways of modeling are different or can be approached any differently.

Thanks.

Answer 1

It is possible – but I’d regard this rather as a dirty hack. After reading my solution, you should step back and think twice if you really want to go this way.

def a(name):
    global_variables = globals()
    try:
        name_of_passed_in_variable = [x for x in global_variables if id(global_variables[x]) == id(name)][0]
    except Exception:
        name_of_passed_in_variable = "unknown"
    print name_of_passed_in_variable, name

my_name = "Tom"
a(my_name)

a("Mike")

second_name = my_name
a(second_name)

Will give the output:

my_name Tom
unknown Mike
my_name Tom

With my examples, you can also see the drawbacks of this approach.

• If you pass in a string directly without assigning a variable, you cannot determine the name
• If you have multiple references to the same variable, you’ll never know which name will be picked up

For the latter problem you could of course implement some logic to cope with it – or maybe this is no problem for you at all.