raphael() wrote:
Hi,
Hello,
I am trying to understand WWW::Mechanize
Did you also look at these pages:
http://search.cpan.org/~petdance/WWW-Mechanize-1.60/lib/WWW/Mechanize/Examples.pod
http://search.cpan.org/~petdance/WWW-Mechanize-1.60/lib/WWW/Mechanize/FAQ.pod
http://search.cpan.org/~petdance/WWW-Mechanize-1.60/lib/WWW/Mechanize/Cookbook.pod
I understand that the downloaded content is stored in content().
Why am I not able to use a regex on it in scalar form?
------code------
use strict;
use warnings;
use WWW::Mechanize;
my $mech = WWW::Mechanize->new();
$mech->get("http://checkip.dyndns.org";);
my $last_page = $mech->content(); # last page fetched
# this works if I store content in an array @last_page
# for ( @last_page ) {
# if ( m/([\d+.]+)/ ) {
# print "$1\n";
# }
# }
$mech->content() returns a scalar value so that is the same as saying:
if ( $last_page[ 0 ] =~ m/([\d+.]+)/ ) {
print "$1\n";
}
# ( my $ip ) = grep/(\d+\.)/, $last_page;
grep() returns the list items that match the expression /(\d+\.)/. The
regular expression is only used to determine which items to return, it
has no effect on the content of those items. If you want to effect the
contents of the list then you have to use map() instead.
( my $ip = $last_page ) =~ m/([\d+\.]+)/;
print "$ip\n";
------end------
my $ip gets the whole source page as its value.
--
Got it while writing out this post :)
--
Now the question becomes what is the difference between these two?
( my $ip = $last_page ) =~ m/([\d+\.]+)/;
That is the same as:
my $ip = $last_page;
$ip =~ m/([\d+\.]+)/;
You are not doing anything with the string stored in $1.
And BTW, '+' is not a valid IP address character.
( my $ip ) = ( $last_page ) =~ m/([\d+\.]+)/;
That is equivalent to:
my $ip;
if ( $last_page =~ m/([\d+\.]+)/ ) {
$ip = $1;
}
I think the above one is "wrong syntax" for using list context?
No, you *have* to use list context or $ip will be assigned the result of
the match operator (true or false) and not the contents of the capturing
parentheses.
Also how can I make grep work?
( my $ip ) = grep/(\d+\.)/, $last_page;
You can't, grep() doesn't work that way. What you are looking for is map():
( my $ip ) = map /([\d.]+)/, $last_page;
Or, since you are not actually using a list, use the /g global option to
the match operator:
( my $ip ) = $last_page =~ /[\d.]+/g;
Note that this will return a list of [\d.]+ strings but only the first
one will be stored in $ip and the rest will be discarded.
John
--
The programmer is fighting against the two most
destructive forces in the universe: entropy and
human stupidity. -- Damian Conway
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