Parenthetical help

eye has asked for the wisdom of the Perl Monks concerning the following question:

In the following code snippet, I don't understand why Perl 5.8.8 says there is a syntax error near ")[" at #3.

#!/usr/bin/perl
use strict;
use warnings;

my $t = (time)[0];          #1
my @t = localtime $t;

@t = localtime ((time)[0]); #2

@t = localtime (time)[0];   #3
[download]

If I comment out #3, both #1 & #2 correctly populate @t. It just seems as though the outer parentheses in #2 should not be needed.

Thanks,
eye

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Re: Parenthetical help by Corion (Patriarch) on Apr 03, 2011 at 15:00 UTC
Perl sees #3 as `@t = localtime(time)` [download] but then encounters `[0]` [download] ... which doesn't make sense to Perl, which means it raises a syntax error.	[reply] [d/l] [select]
Re^2: Parenthetical help by eye (Chaplain) on Apr 04, 2011 at 04:12 UTC
Thanks! Much appreciated.	[reply]
Re: Parenthetical help by jwkrahn (Abbot) on Apr 03, 2011 at 17:55 UTC
BTW, all three are wrong as time always returns a scalar so using a list slice on it makes no sense.	[reply]
Re^2: Parenthetical help by eye (Chaplain) on Apr 04, 2011 at 04:59 UTC
Good point. The code I posted was oversimplified to isolate the issue. The original code was getting the modify time of a file and looked more like: `localtime((stat $file)[9])` [download]	[reply] [d/l]
Re^3: Parenthetical help by jwkrahn (Abbot) on Apr 04, 2011 at 19:35 UTC
The problem is that localtime has a prototype and that prototype says that localtime's first argument, if present, must be a scalar value, so arrays and lists are converted to a scalar value so localtime can use it. $ perl -le'print prototype "CORE::localtime"' ;$ [download]	[reply] [d/l]
Re: Parenthetical help by wind (Priest) on Apr 03, 2011 at 18:37 UTC
As jwkrahn pointed out, time returns a scalar. Also localtime uses `time` as its default. `my @t = localtime; # time assumed as a parameter` [download]	[reply] [d/l] [select]