diff options
| -rw-r--r-- | pod/perldata.pod | 4 | ||||
| -rw-r--r-- | pod/perldiag.pod | 8 | ||||
| -rw-r--r-- | pod/perltie.pod | 8 | ||||
| -rw-r--r-- | pp.c | 3 | ||||
| -rw-r--r-- | pp_hot.c | 3 | ||||
| -rwxr-xr-x | t/op/magic.t | 14 |
6 files changed, 33 insertions, 7 deletions
diff --git a/pod/perldata.pod b/pod/perldata.pod index 572058924f..c58d41974a 100644 --- a/pod/perldata.pod +++ b/pod/perldata.pod @@ -257,7 +257,9 @@ Perl's internal hashing algorithm is performing poorly on your data set. For example, you stick 10,000 things in a hash, but evaluating %HASH in scalar context reveals C<"1/16">, which means only one out of sixteen buckets has been touched, and presumably contains all -10,000 of your items. This isn't supposed to happen. +10,000 of your items. This isn't supposed to happen. If a tied hash +is evaluated in scalar context, a fatal error will result, since this +bucket usage information is currently not available for tied hashes. You can preallocate space for a hash by assigning to the keys() function. This rounds up the allocated buckets to the next power of two: diff --git a/pod/perldiag.pod b/pod/perldiag.pod index b6558ec998..ad5841ca34 100644 --- a/pod/perldiag.pod +++ b/pod/perldiag.pod @@ -912,6 +912,14 @@ for stdout. (F) The script you specified can't be opened for the indicated reason. +=item Can't provide tied hash usage; use keys(%hash) to test if empty + +(F) When a hash is evaluated in scalar context, bucket usage is +returned if the hash is populated, and false is returned if the hash +is empty. Bucket usage is not currently available for tied hashes. +To test if a hash is empty or populated, use keys(%hash) in scalar +context instead. + =item Can't read CRTL environ (S) A warning peculiar to VMS. Perl tried to read an element of %ENV diff --git a/pod/perltie.pod b/pod/perltie.pod index 05b79730c3..3665f0420e 100644 --- a/pod/perltie.pod +++ b/pod/perltie.pod @@ -1076,6 +1076,14 @@ source code to MLDBM. Tied filehandles are still incomplete. sysopen(), truncate(), flock(), fcntl(), stat() and -X can't currently be trapped. +The bucket usage information provided by C<scalar(%hash)> is not +available. If C<%hash> is tied, this will currently result in a +fatal error. + +Counting the number of entries in a hash via C<scalar(keys(%hash))> or +C<scalar(values(%hash)>) is inefficient since it needs to iterate +through all the entries with FIRSTKEY/NEXTKEY. + =head1 AUTHOR Tom Christiansen @@ -107,6 +107,9 @@ PP(pp_padhv) } else if (gimme == G_SCALAR) { SV* sv = sv_newmortal(); + if (SvRMAGICAL(TARG) && mg_find(TARG, PERL_MAGIC_tied)) + Perl_croak(aTHX_ "Can't provide tied hash usage; " + "use keys(%%hash) to test if empty"); if (HvFILL((HV*)TARG)) Perl_sv_setpvf(aTHX_ sv, "%ld/%ld", (long)HvFILL((HV*)TARG), (long)HvMAX((HV*)TARG) + 1); @@ -795,6 +795,7 @@ PP(pp_rv2hv) { dSP; dTOPss; HV *hv; + I32 gimme = GIMME_V; if (SvROK(sv)) { wasref: @@ -808,7 +809,7 @@ PP(pp_rv2hv) RETURN; } else if (LVRET) { - if (GIMME == G_SCALAR) + if (GIMME != G_SCALAR) Perl_croak(aTHX_ "Can't return hash to lvalue scalar context"); SETs((SV*)hv); RETURN; diff --git a/t/op/magic.t b/t/op/magic.t index 3279e1e4ea..f48422b2e3 100755 --- a/t/op/magic.t +++ b/t/op/magic.t @@ -316,16 +316,20 @@ else { skip('no caseless %ENV support') for 1..4; } +{ + no warnings 'void'; + # Make sure Errno hasn't been prematurely autoloaded -ok !defined %Errno::; + ok !defined %Errno::; # Test auto-loading of Errno when %! is used -ok scalar eval q{ - my $errs = %!; - defined %Errno::; -}, $@; + ok scalar eval q{ + %!; + defined %Errno::; + }, $@; +} # Make sure that Errno loading doesn't clobber $! |