Well, yes. I think the 'is' operator is where other attempts fall short, and why it would require a change to Python. But yes, it would need to force the promise. On 17 February 2017 at 21:20, Nathaniel Smith <njs@pobox.com> wrote:
On Thu, Feb 16, 2017 at 9:24 PM, Joseph Hackman <josephhackman@gmail.com> wrote:
Howdy All!
This suggestion is inspired by the question on "Efficient debug logging".
I propose a keyword to mark an expression for delayed/lazy execution, for the purposes of standardizing such behavior across the language.
The proposed format is: delayed: <expr> i.e. log.info("info is %s", delayed: expensiveFunction())
People seem very excited about this as an idea, but I don't understand how it can be implemented.
For example, how do you propose to handle code like this?
value = delayed: some_dict.get("whatever") if value is None: ...
I.e., the question is, how does 'is' work on delayed objects? I guess it has to force the promise and walk the proxy chain in each input and then do an 'is' on the base objects? This seems like a really deep and confusing change to Python's object model for a pretty marginal feature. (This is a special case of the general observation that it's just not possible to implement fully-transparent proxy objects in Python.)
-n
-- Nathaniel J. Smith -- https://vorpus.org