On Wed, Apr 25, 2018 at 4:56 AM, Tim Peters <tim.pet...@gmail.com> wrote:
> [Tim] > >> Binding expressions are debugger-friendly in that they _don't_ just > >> vanish without a trace. It's their purpose to _capture_ the values of > >> the expressions they name. Indeed, you may want to add them all over > >> the place inside expressions, never intending to use the names, just > >> so that you can see otherwise-ephemeral intra-expression results in > >> your debugger ;-) > > > [Steven D'Aprano <st...@pearwood.info>] > wrote: > > That's a fantastic point and I'm surprised nobody has thought of it > > until now (that I've seen). > > > > Chris, if you're still reading this and aren't yet heartedly sick and > > tired of the PEP *wink* this ought to go in as another motivating point. > > You know, I thought I was joking when I wrote that - but after I sent > it I realized I wasn't ;-) > > You just don't realise how perspicacious you truly are, Tim! > It would actually be quite convenient, and far less error-prone, to > add a binding construct inside a complicated expression for purposes > of running under a debugger. The alternative is typing the > sub-expression(s) of interest by hand at the debugger prompt, or > adding print()s, both of which are prone to introducing typos, or > changing results radically due to triggering side effects in the code > invoked by the duplicated sub-expression(s). Adding a binding > construct wouldn't change anything about how the code worked (apart > from possibly clobbering a local name). Indeed, in the cases where I currently find myself unwrapping expressions to capture their values in local variables for debugging purposes it would usually be far less intrusive to bind a name to the expression inline, then use the debugger to inspect the value.
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
