Re: Re: Re: Idiomatic optimizations

[hakkr]

Always pass referances not data structures hence \ operator is an optimistaion sub(\@array) instead of sub(@array)
Only use what you need from modules use CGI qw(:standard);
Also I like shortcut operators

my $i ||=0 ;
my $i =shift || 0;

also I like ? operator instead of if's

$i?$i=1:$i=0;

is !~ an optimisation over just negating the result of =~, I dunno but I think !~ looks better

[Joost]

Just a few remarks (though i've got a sneaking suspicion i'm correcting typos here):

> my $i ||=0 ;

here $i will always turn out to be 0 (because of the my operator), so my $i=0; is more efficient.

> $i?$i=1:$i=0;

How about $i=$i?1:0; - that's also a bit more readable. (at least to my eyes).

Joost.

[tadman]

Don't forget that ?: can get dangerous, not unlike juggling running chainsaws. It's a great show, but is liable to injure yourself something fierce:

$foo = $a? $b? $c : $d? $e : $f : $g : $h;

Sometimes an if is more verbose, but undeniably precise.

Instead of getting carried away with ?:, you can sometimes compact it using the regular logical operators || and &&. It really depends on what you're working with.

[demerphq]

Hmm I sort of agree with your point, but Im troubled by your fierce but syntactically incorrect example (ternary ops should always have the same number of '?' as ':' )

$a=1;$b=2;$c=3;$d=4;$f=5;$g=6;$h=7;
$foo = $a? $b? $c : $d? $e : $f : $g : $h;
print $foo;
__END__
syntax error at C:\temp\ternary.pl line 2, near "$g :"
Execution of C:\temp\ternary.pl aborted due to compilation errors.

I believe that you meant to say

$foo = $a ? $b ? $c : $d ? $e : $f : $g;

My personal rule of thumb is that ternary ops should not be nested but may be chained. Thus I would say that your example could be rewritten

$foo = !$a ? $g : $b ? $c : $d ? $e : $f;

And its a little less troublesome. Even then I personally would add some whitespace so it would look like

$foo = !$a ? $g
           : $b ? $c
                : $d ? $e
                     : $f;

This and a bit of paretheses would also help your nested example

$foo = $a ? ($b ? $c 
                : ($d ? $e 
                      : $f)) 
          : $g;

I find that formatting ternaries like this makes them only marginally more difficult to read than if statements, but I still tend to avoid nested ternaries.

Yves / DeMerphq
---
Writing a good benchmark isnt as easy as it might look.

[Juerd]

$i?$i=1:$i=0;

Puh-lease, use some whitespace! Here are some alternatives:

$i ? $i = 1 : $i = 0;
$i = $i ? 1 : 0;

$i = !!$i || 0;

$foo = $foo ? 1 : 0; # Single-letter variable names:
                     # easy to type, hard to read

Always pass referances not data structures

Most references are the root of data structures, so I think you meant "Always pass references instead of flattened hashes or lists". Note that you can't use this if the sub in question doesn't expect it.

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