Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread Greg Ewing
David Mertz wrote: I guess once in a while we'll see e.g. `Sequence[CustomThing]`, but it will be uncommon for that typing involving `CutomThing` to be within CustomThing itself I think that depends on what kind of software you're writing. Anything involving any kind of trees or graphs will h

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread אלעזר
On Fri, Sep 23, 2016 at 5:54 AM Chris Angelico wrote: > On Fri, Sep 23, 2016 at 12:35 PM, Steven D'Aprano > wrote: > > The straight-forward and simple way of writing a recursive spam() > > function surprises beginners, but they might go years or their entire > > career without running into a sit

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread אלעזר
On Fri, Sep 23, 2016 at 6:06 AM Steven D'Aprano wrote: > On Thu, Sep 22, 2016 at 07:21:18PM +, אלעזר wrote: > > On Thu, Sep 22, 2016 at 9:43 PM Steven D'Aprano > wrote: > > > > > On Thu, Sep 22, 2016 at 05:19:12PM +, אלעזר wrote: > > > > Hi all, > > > > > > > > Annotations of function pa

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread אלעזר
On Fri, Sep 23, 2016 at 6:24 AM Nick Coghlan wrote: > On 23 September 2016 at 13:06, Steven D'Aprano > wrote: > > On Thu, Sep 22, 2016 at 07:21:18PM +, אלעזר wrote: > >> "Expression" is something that you need its value right > >> now, and "annotation" is something that, well, annotates the

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread Steven D'Aprano
On Fri, Sep 23, 2016 at 10:17:15AM +, אלעזר wrote: > On Fri, Sep 23, 2016 at 6:06 AM Steven D'Aprano wrote: > > On Thu, Sep 22, 2016 at 07:21:18PM +, אלעזר wrote: > > > On Thu, Sep 22, 2016 at 9:43 PM Steven D'Aprano wrote: > > > > On Thu, Sep 22, 2016 at 05:19:12PM +, אלעזר wrote: > >

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread אלעזר
On Fri, Sep 23, 2016 at 3:11 PM Steven D'Aprano wrote: > On Fri, Sep 23, 2016 at 10:17:15AM +, אלעזר wrote: > > On Fri, Sep 23, 2016 at 6:06 AM Steven D'Aprano > wrote: > > > On Thu, Sep 22, 2016 at 07:21:18PM +, אלעזר wrote: > > > > On Thu, Sep 22, 2016 at 9:43 PM Steven D'Aprano wrote:

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread Chris Angelico
On Fri, Sep 23, 2016 at 11:58 PM, אלעזר wrote: > What other context you see where the result of an expression is not intended > to be used at all? Well there's Expression statements, which are evaluated > for side effect. There's docstrings, which are a kind of annotations. What > else? The only o

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread Nick Coghlan
On 23 September 2016 at 20:31, אלעזר wrote: > On Fri, Sep 23, 2016 at 6:24 AM Nick Coghlan wrote: >> It's not a substitute for something like click or argparse when it >> comes to more complex argument parsing, but it's a good example of the >> kind of simple pseudo-DSL folks have long been able

Re: [Python-ideas] Delay evaluation of annotations

2016-09-23 Thread Nick Coghlan
On 24 September 2016 at 01:58, Chris Angelico wrote: > Default arguments trip some people up because they expect them to be > evaluated when the function's called, but it can easily be explained. > Function annotations are exactly the same. Making them magically > late-evaluate would have conseque