[Python-ideas] Object for accessing identifiers/names

[Steven D'Aprano]

On Wed, Jun 01, 2016 at 10:22:39PM +0300, Koos Zevenhoven wrote:

> Currently, there is no direct way to work with variable names from within
> Python. Yes, you can fiddle with __dict__s and locals() and globals(),

The usual way is to write the name as a string and operate on the 
namespace.

That means that variables (names) are not themselves values: a name is 
bound to a value, but there is no value which is itself a name. Instead, 
we use a string as a form of indirection.

> but
> there is no ​convenient​ general way. To solve this, there could be a way
> ​(probably new syntax)​ for creating an object that
> can examine and manipulate a name binding conveniently.

Before getting too interested in the syntax for creating these, can you 
explain what you want to do with them? Most uses of names don't need to 
be values:

spam = 23
import spam
del spam

all work well on their own. Can you give some use-cases?


> The object could be created for instance as follows:
> ​ ​
> name_object = identifier some_name

How would that be different from this?

name_object = 'some_name'


> Now this name_obj​ thing​
> could provide functionality like assigning to the name some_name, getting
> the assigned object, and determining whether
> ​something has been assigned to the name or not.

Most of these things already work using strings:

# bind a name to the global scope
globals()[name_object] = 999

# lookup a name in some module's namespace
vars(module)[name_object]

# check for existence
name_object in vars(module)

What functionality do you think is missing?



-- 
Steve