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Postings from June 2022
On Fri, 24 Jun 2022 at 04:52, Graham Knop <haarg@haarg.org> wrote:
> On Wed, Jun 22, 2022 at 1:19 AM Yuki Kimoto <kimoto.yuki@gmail.com> wrote:
> >
> > Summary.
> >
> > Are we going in the following direction?
> >
> > If the "yield_true" feature is enabled,
> >
> > - the effect is local-scope. Generally the "yield_true" feature is
> used at the top level file scope.
> > - It has no effect on the return value of .pm file. Both an implicit
> return value and an explicit return value specified by return statement.
> > - "require" ignores the return value to determine if the module was
> successfully loaded.
> > - "require" returns the return value of .pm file just like the current
> behavior.
> >
>
> I think having require return the last value from the file would be a
> terrible change.
>
It already returns the last value _if it was true_, so I think this
description is a bit misleading - the concern here could be reworded as
"require should never return false", since that'd be what breaks the eval {
require } combination?
Again, I think this is long past any reasonable "pre-RFC" stage, and it'd
make more sense to continue the discussion based on a real RFC, but:
- `perldoc -f require` includes a Perl implementation of (most of) the
require() functionality
- that seems like a good starting point to summarise the proposed change as
hopefully-unambiguous code
Would this be accurate, for example:
use Carp 'croak';
use version;
sub require {
my ($filename) = @_;
if ( my $version = eval { version->parse($filename) } )
{
if ( $version > $^V ) {
my $vn = $version->normal;
croak "Perl $vn required--this is only $^V,
stopped";
}
return 1;
}
if (exists $INC{$filename}) {
return 1 if $INC{$filename};
croak "Compilation failed in require";
}
foreach $prefix (@INC) {
if (ref($prefix)) {
#... do other stuff - see text below ....
}
# (see text below about possible appending of .pmc
# suffix to $filename)
my $realfilename = "$prefix/$filename";
next if ! -e $realfilename || -d _ || -b _;
$INC{$filename} = $realfilename;
my $result = do($realfilename);
# but run in caller's namespace
if (!defined $result) {
$INC{$filename} = undef;
croak $@ ? "$@Compilation failed in require"
: "Can't locate $filename: $!\n";
}
- if (!$result) {
+ if (!$result and
!$^H{require_without_throwing_exceptions_when_false_feature_formerly_described_as_yield_true})
{
delete $INC{$filename};
croak "$filename did not return true value";
}
+ $result ||= builtin::true;
$! = 0;
return $result;
}
croak "Can't locate $filename in \@INC ...";
}
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