Harry Putnam wrote:
:
: My script has a function that I want to just print its
: output in some circumstances but in others I need to
: capture its output into an array for further processing:
:
: sub strip_to_bone {
: if(/[Ss]ource/ && /[Dd]estination/){
: ($line = $line) =~ s/[Ss]ource/Src/g;
: ($line = $line) =~ s/[Dd]estination/Dst/g;
: $line =~ s/(^[^ ]+, )([0-9][^ ]+ [0-9][^ ]+)(.*)(Src[^ ]+
: [0-9]+)(.*)(Dst[^ ]+ [0-9]+)/$2 $4 $6/;
: $line = '';
: printf " %s %s %-28s %s\n", "<$.>", "$2", "$4", "$6";
: }
: }
Sorry Harry. This reply doesn't answer your question.
But your subroutine raises some excellent reasons why a
better defined programming style can save keystrokes and
headaches later on.
One approach to subroutine management is not to
allow subroutines to print anything. Certainly, this
is not a hard and fast rule, but if this sub routine
had been written with that in mind, it my look more
like the following.
print strip_to_bone();
sub strip_to_bone {
# process data
return
sprintf " %s %s %-28s %s\n",
$line_number, $2, $4, $6;
}
With this style your solution would be:
my @c = strip_to_bone();
Another good habit is to pass all data into the
subroutine. Any external value should be passed.
The sub shouldn't affect its outside environment.
Again, this is not a hard and fast, but it makes
for easier maintenance down the road.
print strip_to_bone( $line, $., $_ );
sub strip_to_bone {
my( $line, $line_number, $foo ) = @_;
# process data
return
sprintf " %s %s %-28s %s\n",
$line_number, $2, $4, $6;
}
If the subroutine changes $line, $line_number,
or $foo it won't affect the rest of the program.
This is a real boon when debugging.
Unfortunately, your subroutine is printing
something *and* manipulating the external
variable $line. So we have to cheat on one of
the style rules we just established. (Actually,
we probably don't - but we don't access to the
rest of the script.)
The easiest way to do this is to send $line
as a reference.
print strip_to_bone( \$line, $., $_ );
sub strip_to_bone {
#
# This function modifies the external variable $line
#
my( $line, $line_number, $foo ) = @_;
if ( $foo =~ /[Ss]ource/ && $foo =~ /[Dd]estination/ ) {
$$line =~ s/[Ss]ource/Src/g;
$$line =~ s/[Dd]estination/Dst/g;
$$line =~ /^[^ ]+, (\d[^ ]+ \d[^ ]+).*(Src[^ ]+ \d+).*(Dst[^ ]+
\d+)/;
$$line = '';
return
sprintf " %s %s %-28s %s\n",
$line_number, $1, $2, $3;
}
return '';
}
HTH,
Charles K. Clarkson
--
Head Bottle Washer,
Clarkson Energy Homes, Inc.
Mobile Home Specialists
254 968-8328
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