Re: [PATCH v2 00/10] send-email: various optimizations to speed up by >2x

From: Felipe Contreras <felipe.contreras@gmail.com>
Date: May 30, 2021, 16:07 UTC
Message-ID: <60b3b84967a62_b937208c@natae.notmuch>
In-Reply-To: <877djg313c.fsf@evledraar.gmail.com>

Ævar Arnfjörð Bjarmason wrote:

Show 37 quoted lines

> 
> On Sat, May 29 2021, Felipe Contreras wrote:
> 
> > Ævar Arnfjörð Bjarmason wrote:
> >> 
> >> On Fri, May 28 2021, Felipe Contreras wrote:
> >> 
> >> > Ævar Arnfjörð Bjarmason wrote:
> >> >> Returning a flattened list is idiomatic in Perl, it means that a caller
> >> >> can do any of:
> >> >> 
> >> >>     # I only care about the last value for a key, or only about
> >> >>     # existence checks
> >> >>     my %hash = func();
> >> >
> >> > I was staying on the sideline because I don't know what's idiomatic in
> >> > Perl, but Perl and Ruby share a lot in common (one could say Perl is the
> >> > grandfather of Ruby), and I do know very well what's idiomatic in Ruby.
> >> >
> >> > In perl you can do $ENV{'USER'}, and:
> >> >
> >> >   while (my ($k, $v) = each %ENV) {
> >> >     print "$k = $v\n";
> >> >   }
> >> >
> >> > Obviously it's idiomatic to use hashes this way [1].
> >> 
> >> For what it's worth idiomatic/good idea and "has an example in the perl
> >> documentation" unfortunately aren't always aligned. A lot of experienced
> >> Perl programmers avoid each() like the plague:
> >> http://blogs.perl.org/users/rurban/2014/04/do-not-use-each.html
> >
> > Perl is an old language, and each() was introduced in 2010, it's
> > expected that some old-timers would not adapt to the new idioms.
> 
> each() has been in Perl since 1987 with perl v1.0, you must be confusing
> it with something else.

I see. I read the each() documentation [1] too hastily:

  When called on a hash in list context, returns a 2-element list
  consisting of the key and value for the next element of a hash. In
  Perl 5.12 and later only...

> In any case, the recommendation against it has nothing to do with its
> age, it's that similar to strtok() it has global state.

Yes, that's what I understood from the blog post you shared, but at least personally I never assume I can modify a hash like that. I see why some people need to be careful with it, but "avoid it like the plague" seems way too defensive programming to me.

[1] https://perldoc.perl.org/functions/each

-- 
Felipe Contreras