Re: [Python-ideas] Return for assignment blocks

Oct. 24, 2018

      On Wed, Oct 24, 2018 at 7:55 AM Rhodri James <rhodri@kynesim.co.uk> wrote:
...
On 24/10/2018 15:04, Calvin Spealman wrote:
...
My idea is not "assignment blocks" those already exist. `def` and `class`
blocks are both syntaxes that assign to some name. I'm just using the
term
to refer to them as a group.
The proposal is just being able to return them. These two examples become
equivalent:
def ignore_exc(exc_type):
     return def (func):
         @wraps(func)
         return def (*args, **kwargs):
             try:
                 return func(*args, **kwargs)
             except exc_type:
                 pass
def ignore_exc(exc_type):
     def decorator(func):
         @wraps(func)
         def wrapped_func(*args, **kwargs):
             try:
                 return func(*args, **kwargs)
             except exc_type:
                 pass
         return wrapped_func
     return decorator
Essentially this is a limited multi-line lambda.  Either people are
going to be surprised that you can only use it in a return statement or
you have to open the whole can of worms about multi-line lambdas.  Good
luck on the latter.
Let's close that can quickly. Syntactically this is much simpler because
because there's no trouble with switching between expression-mode and
statement-mode. Also note that syntactically it is clearly a special form
of `def` statement -- it can even be decorated!

So let's review the proposal as a shorthand for defining a function and
immediately returning it. It saves one line plus picking a name. I
personally don't think that's enough of a benefit to warrant the extra
syntactic complexity (even if modest).

-- 
--Guido van Rossum (python.org/~guido)