SPUG: spug: What is the idiomatic way to extract first/last item after split?

[John W. Krahn]

Uri London wrote:
> 
> What is the idiomatic way to extract first/last item after split?

my ( $first, $last ) = ( split )[ 0, -1 ];


> More interestingly, why #2 doesn't work, while #3 does?
> 
> For example:
> 
> $path = `cd`;

You should use the Cwd module for that:

use Cwd;

my $path = getcwd;


> # 1. working, but I've been told not very efficient:
> $base = (split /\\/, $path)[-1];

Who told you that?  Did you compare it to other methods with the Benchmark module?


> # 2. this isn't working for me. Why???
> $base = pop split /\\/, $path;

pop(), push(), shift(), unshift() and splice() require that the first argument 
is an array.  They do not work with lists.

perldoc -q "What is the difference between a list and an array"


So if you convert that to an array:

my $base = pop @{[ split /\\/, $path ]};


> # 3. This is similar to above, but does work.
> @tmp = split /\\/, $path;
> $base = pop @tmp;
> 
> # 4. Work, but I believe slower:
> ($base) = $path =~ /.*\\([^\\])/;

If speed is your main goal then you should compare various methods using the 
Benchmark module.  If compatibility and re-use is more important then have a 
look at the File::Spec module.

perldoc File::Spec



John
-- 
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program
fulfillment