Re^2: Conditional initialization of lexical (my) variables

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Re^3: Conditional initialization of lexical (my) variables by choroba (Cardinal) on May 10, 2023 at 18:18 UTC
`perl -wE 'BEGIN { print $] } my $x if 0' 5.037003 This use of my() in false conditional is no longer allowed at -e line +1.` [download] `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l] [select]
Re^4: Conditional initialization of lexical (my) variables by hv (Prior) on May 10, 2023 at 18:38 UTC
Ah ok, that appears to be a quite specific case being caught, I would guess during constant folding: `% /opt/v5.36.0/bin/perl -wlE 'BEGIN { print $] } my $x if $ARGV[0]' 0 5.036000 % /opt/v5.36.0/bin/perl -wlE 'BEGIN { print $] } my $x if $ARGV[0]' 1 5.036000 %` [download]	[reply] [d/l]
Re^4: Conditional initialization of lexical (my) variables by LanX (Saint) on May 10, 2023 at 20:58 UTC
not the same thing This `my $x if 0` is definitely a bug, because constant folding shouldn't allow a lexical to be declared. But the OP has a condition which is only checked at run-time, while the declaration happens at compile-time. This means the new variable will not be overwritten with an init-value if the condition is false. The deeper issue is that postfix-conditions have no own scope, the problem is non-existent for `if ($bool) {my $x = ... }` Not sure if this qualifies as a bug or a weird feature. But a warning should happen in any case if a declaration happens before a postfix condition, because of the broken symmetry to prefix conditions. Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l] [select]