Re^3: How could I check if a variable is 'read-only'?

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Re^4: How could I check if a variable is 'read-only'? by kschwab (Vicar) on Jan 02, 2019 at 14:39 UTC
There does look like one possibility. Perlguts mentions that with Perl 5.16 and earlier: Copy-on-write (see the next section) shared a flag bit with read-only scalars. So the only way to test whether sv_setsv , etc., will raise a "Modification of a read-only value" error in those versions is: SvREADONLY(sv) && !SvIsCOW(sv) Scalar::Util doesn't do anything special for 5.16 or earlier, so it could have false positives in that case. Of course, 5.18 (where it's fixed) was released in 2013 :)	[reply]
Re^4: How could I check if a variable is 'read-only'? by Anonymous Monk on Jun 14, 2019 at 23:50 UTC
What do you make of this? `#!/usr/bin/env perl use strict; use warnings; use JSON; use Scalar::Util qw/ readonly /; my $data = decode_json('{ "val":false }'); print "readonly: ", readonly($data->{val}) ? 'yes' : 'no', "\n"; bless $data->{val};` [download] That produces this for me (on Perl 5.18.2): `$./try readonly: no Modification of a read-only value attempted at ./try line 10.` [download]	[reply] [d/l] [select]
Re^5: How could I check if a variable is 'read-only'? by Anonymous Monk on Jun 15, 2019 at 19:44 UTC
cant reproduce that here, try upgrading perl and or json module	[reply]
Re^6: How could I check if a variable is 'read-only'? by Your Mother (Archbishop) on Jun 15, 2019 at 19:56 UTC
Or cite yours…? `readonly: no Modification of a read-only value attempted at - line 9. # Successfully installed JSON-4.02 (upgraded from 2.97001) readonly: no Modification of a read-only value attempted at - line 8. # Scalar::Util is up to date. (1.50) perl -MScalar::Util=readonly -MJSON -E 'say readonly(JSON::false) ? "r +eadonly" : "ReAdOnLY"' ReAdOnLY # This is perl 5, version 18, subversion 4 (v5.18.4)` [download]	[reply] [d/l]
Re^7: How could I check if a variable is 'read-only'? by choroba (Cardinal) on Jun 15, 2019 at 20:00 UTC