From: Mike McClain <mmccl...@nethere.com>
> On Fri, Jan 09, 2009 at 05:52:45PM -0500, Chas. Owens wrote:
> <snip>
> > You seem to be under the impression that the argument to
> > Digest::MD5::md5_hex is a file name. The argument is a scalar holding
> > the data to perform md5 on. So Digest::MD5::md5_hex("foo") will give
> > you the MD5 of the data "foo". When you say
> > Digest::MD5->md5_hex("foo") you are really saying
> > Digest::MD5::md5_hex("Digest::MD5", "foo") so you will get the MD5 of
> > the string "Digest::MD5" concatenated with the string "foo".
>
> When you said, "Module::method('Module', $arg)" I saw the second 'Module'
> as file not string.
> I guess I've still got a lot to learn.
>
> I see that
> Digest::MD5->md5_hex()
> "Digest::MD5"->md5_hex()
> Digest::MD5::md5_hex("Digest::MD5") all return the same result.
> "Mud"->md5_hex() is an error.
>
> But after I read all the references in the index of 'Programming Perl'
> about '->' the arrow operator I'm no where nearer to understanding
> what's going on. At least thanks to your help I know what's going on
> even if I don't yet understand it. It's been long enough since I picked
> up a new language to have forgotten this particular frustration.
> Cest la vie.
The Class::Name->method(...) is a class method call. Perl will find
the method in the clas hierarchy and call the method and pass the
'Class::Name' as the first parameter.
>
> <snip>
>
> > seek DATA, 0, 0;
> > my $data = join '', <DATA>;
>
> This is interesting.
> The 'join' causes the whole file to be slurped in by forcing list context?
Yes. But it's inefficient. This forces perl to first split the file
into lines and then merge them back.
my $data = do {local $/; <DATA>};
is more efficient.
The "local $/" clears the "line separator for reading" and thus
forces the <> (diamond operator) to return the whole file contents as
a single scalar.
Jenda
===== je...@krynicky.cz === http://Jenda.Krynicky.cz =====
When it comes to wine, women and song, wizards are allowed
to get drunk and croon as much as they like.
-- Terry Pratchett in Sourcery
--
To unsubscribe, e-mail: beginners-unsubscr...@perl.org
For additional commands, e-mail: beginners-h...@perl.org
http://learn.perl.org/
