[Python-ideas] Jump to function as an an alternative to call function

[Steven D'Aprano]

On Thu, Aug 16, 2018 at 09:34:57AM -0700, Chris Barker wrote:
> On Thu, Aug 16, 2018 at 1:28 AM, Steven D'Aprano <steve at pearwood.info>
> wrote:
> 
> > there
> > are times where I have really wanted to access the caller's environment,
> > not the environment where my function was defined.
> >
> 
> what am I missing? can't you get that by passing locals() in to a function?

I want to pull in the caller's environment, not require the caller to 
push their environment in to me.

Most of the time I just want read-access to the environment, but if I 
need to modify it, and the OP needs to do that, modifying locals() is 
unreliable. In general, it just silently fails, because locals() 
returns a copy of the local namespace.


def spam(d):
    d['a'] = 'spam'

def eggs():
    a = 'ham'
    spam(locals())
    print(a)

Running that under CPython prints "ham", not "spam".

(To be precise, writing to locals() works when you are in the module 
scope, or a class body, but not a function body. That's a CPython 
implementation detail; IronPython and Jython may behave differently.)



-- 
Steve