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Postings from January 2022
On Tue, 25 Jan 2022 at 20:15, <yb@rslinux.fun> wrote:
> On Tue, Jan 25, 2022 at 02:37:19PM +0000, hv@crypt.org wrote:
> > In this case, it's an inline recursive function of which the relevant
> > parts look a bit like:
> >
> > sub do_stuff {
> > my $prod = 1;
> > my $recurse;
> > $recurse = sub {
> > ...
> > for my $new (@interesting_values) {
> > local $prod = $prod * $new; # aspirational
> > $recurse->();
> > }
> > };
> > $recurse->();
> > }
> >
> > .. so shadowing doesn't help. Alternatives such as a) making it a
> > one-element array, b) passing it as an argument or c) manually
> > saving and restoring are all possible, but all likely to be slower,
> > more error-prone, and add complexity to already-complex code.
> >
> > The real code's aim is to find new values for https://oeis.org/A292580.
> > It's very much a work-in-progress, but if you're interested look at
> > https://github.com/hvds/seq/blob/master/divrep/oul#L167 for current
> > implementation (as one-element array).
> >
> > Hugo
>
> Though personally I would agree with demerphq to just use a localized
> global, I think one way around this to get what you want is to write:
>
> my $h = {prod => 1};
> ...
> $recurse = sub {
> ...
> local $h->{prod} = $h->{prod} * $new;
> ...
> };
>
Nod, but I might use an array instead of a hash, if speed is a concern.
Yves
--
perl -Mre=debug -e "/just|another|perl|hacker/"
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