Jakob Lell <[EMAIL PROTECTED]> wrote:
:
: you can use prototypes to pass array references.
: see perldoc perlsub for more details.
:
: sub showIt([EMAIL PROTECTED]@);
: my @alpha=("a","b","c");
: my @numer=(1,2,3);
: showIt(@alpha,@numer);
: sub showIt([EMAIL PROTECTED]@)
: {
: my($a,$b) = @_;
: print "a[0]:" . $$a[0] . "\n"; #accessing by reference
: print "b[0]:" . $$b[0] . "\n";
: }
I also felt prototyping was a superior method to
handle subroutine calls. But I found it has some
limitations. About this same time I adopted the
philosophy that, except in rare cases, subroutines
should not change their input data.
Here's an example ($w, $x, $y, and $z are
references to arrays):
Here I choose to change the values in $x and
$y:
my( $x, $y ) = some_sub( $x, $y );
In this case I choose to preserve the values
in $x and $y:
my( $w, $z ) = some_sub( $x, $y );
One advantage to this preservation of input
data is that I can use data that is read-only.
Like a list:
my( $w, $z ) = some_sub( $x, some_other_sub( $y ) );
This leads to another style rule. When
returning a list or an array, return references.
If I use prototypes I'll need to wrap subroutine
returns in @{}:
my( $w, $z ) = proto_sub(
@x,
@{ other_proto_sub( @x, @y, ) }
);
@{} looks messy and it converts one sub's
output to an array just to put it back into a
reference that we had in the first place.
So, to increase readability and consistency
I decided to avoid using prototypes.
Just my $.03 (I'm a big spender),
Charles K. Clarkson
--
Head Bottle Washer,
Clarkson Energy Homes, Inc.
Mobile Home Specialists
254 968-8328
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