How to get the variable names from the string for the format() method

Question

Lets say I have this line:

"My name is {name}".format(name="qwerty")

I know that the variable name is name and so I can fill it. But what if the word inside the {} always changes, like this:

"My name is {name}"
"My name is {n}"
"My name is {myname}"

I want to be able to do this:

"My name is {*}".format(*=get_value(*))

Where * is what ever word was given inside the {}

Hope I was clear.

---

EDIT:

def get_value(var):
    return mydict.get(var)

def printme(str):
    print str.format(var1=get_value(var1), var2=get_value(var2))

printme("my name is {name} {lastname}")
printme("your {gender} is a {sex}")

Having this, I can't hard code any of the variables inside printme function.

Answer 1

You can parse the format yourself with the string.Formatter() class to list all references:

from string import Formatter

names = [fn for _, fn, _, _ in Formatter().parse(yourstring) if fn is not None]

Demo:

>>> from string import Formatter
>>> yourstring = "My name is {myname}"
>>> [fn for _, fn, _, _ in Formatter().parse(yourstring) if fn is not None]
['myname']

You could subclass Formatter to do something more fancy; the Formatter.get_field() method is called for each parsed field name, for example, so a subclass could work harder to find the right object to use.