PERL Programming - what is this ?

Author

what is this ?

George Bouras

2004-07-29, 3:55 am

normal array slice
@array[0,1,23,100]

what is this ?
@array["hello1","hello2", ...];

Joe Smith

2004-07-29, 3:55 am

George Bouras wrote:

> normal array slice
> @array[0,1,23,100]
>
> what is this ?
> @array["hello1","hello2", ...];

Since "hello1" is zero when evaluated in numeric context, it is the same as
@array[0,0] which is ($array[0],$array[0]).

Now, if you were using braces {} instead of brackets [], the answer would
be different.
-Joe

gnari

2004-07-29, 3:55 am

"George Bouras" <gravitalsun.ANTISPAM@yahoo.com> wrote in message
news:ce50mn$2b2k$1@ulysses.noc.ntua.gr...
> normal array slice
> @array[0,1,23,100]
>
> what is this ?
> @array["hello1","hello2", ...];

you probably mean this:
@array{"hello1","hello2", ...};

in that case, it is a hash slice, equivalent to:
($array{'hello1'},$array{'hello2'},...);

gnari

George Bouras

2004-07-29, 3:55 am

I read it at POE Perl module documentation.

sub handler_start
{
my ($kernel, $heap, $session) = @_[KERNEL, HEAP, SESSION];
....
}

I think it must be something similar to

use constant A=>1;
use constant B=>7;
use constant C=>9;

f1( qw/a b c d e f g h i j k l m n o p q/ );

sub f1
{
my ($a,$b,$c) = @_[A,B,C];
print "$a $b $c\n";
}

George Bouras

2004-07-29, 3:55 am

I read it at POE samples and documentation.

sub handler_start
{
my ($kernel, $heap, $session) = @_[KERNEL, HEAP, SESSION];
....
}

I think it must be something similar to

use constant A=>1;
use constant B=>7;
use constant C=>9;

f1( qw/a b c d e f g h i j k l m n o p q/ );

sub f1
{
my ($a,$b,$c) = @_[A,B,C];
print "$a $b $c\n";
}

Matt Garrish

2004-07-29, 3:55 am

"George Bouras" <gravitalsun.ANTISPAM@yahoo.com> wrote in message
news:ce56dv$2nft$1@ulysses.noc.ntua.gr...
> I read it at POE Perl module documentation.
>
> sub handler_start
> {
> my ($kernel, $heap, $session) = @_[KERNEL, HEAP, SESSION];
> ...
> }
>
>
>
> I think it must be something similar to
>
> use constant A=>1;
> use constant B=>7;
> use constant C=>9;
>
> f1( qw/a b c d e f g h i j k l m n o p q/ );
>
> sub f1
> {
> my ($a,$b,$c) = @_[A,B,C];
> print "$a $b $c\n";
> }
>

See POE::Session for more information. In essence you are correct about them
being constants:

Each session maintains its unique runtime context. Sessions pass their
contexts on to their states through a series of standard parameters. These
parameters tell each state about its Kernel, its Session, itself, and the
events that invoke it.

State parameters' offsets into @_ are never used directly. Instead they're
referenced by symbolic constant. This lets POE to change their order without
breaking programs, since the constants will always be correct.

Matt

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