p5pRT
commented
24 years ago From epa98@doc.ic.ac.uk
Created by epa98@doc.ic.ac.uk
If you accidentally use something like tr/\d// on a reference\, the variable becomes stringified without any warning. Later on if you try to use it as a reference\, the error message produced is confusing.
#!/usr/bin/perl -w use IO::File; use strict; use diagnostics; my $t = IO::File->new_tmpfile(); if ($t =~ tr/\d//) { print "string $t contains digits\n"; } $t->close();
A better error message would warn that the variable had been stringified earlier on and had lost its reference-ness. Alternatively you could give a warning when the stringification happens\, or even a fatal error. (Nobody would really want to use tr/// on a reference\, it must be a mistake.)
I reported this to comp.lang.perl.moderated and Yitzchak Scott-Thoennes \sthoenna@​efn\.org suggested a fix:
s/// is broken\, too.
Here's one way to fix tr///:
Inline Patch
```diff --- doop.c.orig Fri Sep 1 14:09:46 2000 +++ doop.c Sat Sep 9 22:37:38 2000 @@ -438,7 +438,7 @@ I32 hasutf = (PL_op->op_private & (OPpTRANS_FROM_UTF|OPpTRANS_TO_UTF)); - if (SvREADONLY(sv) && !(PL_op->op_private & OPpTRANS_IDENTICAL)) + if ((SvREADONLY(sv) || SvROK(sv)) && !(PL_op->op_private & OPpTRANS_IDENTICAL)) Perl_croak(aTHX_ PL_no_modify); (void)SvPV(sv, len); ```End of Patch.
but that would prevent doing anything useful with an overloaded object (but that should be ok since it is broken as it is now). And the error message may need to be more specific.
Are there any cases where a non-readonly non-reference would have get magic but not set magic? If so\, these would be broken too.
I also noticed that $x =~ tr/x// is calling get magic twice.
Migrated from rt.perl.org#4282 (status was 'resolved')
Searchable as RT4282$