Uniforming decorator for functions and classes to retrieve varname

[pwwang]

Now we are able to do this with class:

from varname import inject_varname

@inject_varname
class Dict(dict):
    pass

a = Dict(a=1)
b = Dict(b=2)
a.__varname__ == 'a'
b.__varname__ == 'b'
a.update(b)
a == {'a':1, 'b':2}

Try to extend it to functions:

@inject_varname
def func():
  return __varname__

f = func() # f == 'f'

How it works:

def inject_varname(func):

    def wrapper():
        # get by varname.varname, also inherit the arguments from it for the decorator.
        func.__globals__['__varname__'] = var_name # get by varname.varname
        try:
          return func()
        finally:
          del func.__globals__['__varname__']

    return wrapper

Also considering rename inject_varname into register.