Re: Avoiding repeated undefs

Hello davies,

> It seems to me to be inelegant to repeat undef

No, is not. Compiler does not bother with elegance ;)

Anyway I suspect you cannot avoid them repeated: you are are in left side of an assignement, and inside a my declaration: no array (well you mean list?) can be there.

An eventual list as second (or whatever..) element in the assignement will slurp everything


perl -e "$str = 'a b c d e f g';@arr=(1,2,3,4,5); ($key, @arr, $val) =
+ split(/\s+/, $str); print  qq($key $val\n@arr\n)"

a
b c d e f g

# even if the array is presized:

perl -e "$str = 'a b c d e f g';$#arr=4; ($key, @arr, $val) = split(/\
+s+/, $str); print  qq($key $val\n@arr\n)"

a
b c d e f g
[download]

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

Comment on Re: Avoiding repeated undefs Download Code

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Re^2: Avoiding repeated undefs by hippo (Archbishop) on Feb 26, 2019 at 10:08 UTC
even if the array is presized If you specify the slice in the assignment it's fine though: `use strict; use warnings; use Test::More tests => 1; $_ = "Anyway I suspect you cannot avoid them repeated: you are are in +left side"; my @undef; my ($key, $val); ($key, @undef[0..4], $val) = split(/\s+/, $_); is ($val, 'them');` [download] I still prefer Eily's approach, however.	[reply] [d/l]
Re^3: Avoiding repeated undefs by rsFalse (Chaplain) on Feb 28, 2019 at 00:15 UTC
Similar approach: `( my $key, (undef) x 5, my $val) = split(/\s+/, $_);` [download] Note: 'undef' must be enclosed with parentheses to force list context for 'x' operator.	[reply] [d/l]
Re^4: Avoiding repeated undefs by choroba (Cardinal) on Feb 28, 2019 at 06:37 UTC
Note that you need 5.22 for this to work. See Assignment to list repetition in Perl 5.22 delta. See also `()x=` in Syntax::Construct. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l] [select]