CODEWITHSUNDEEP
perl
CJ7
CJ7

Reputation: 23295

Effect of use Encode qw/encode decode from_to/;?

What is the effect of this at the top of a perl script?

use Encode qw/encode decode from_to/;

I found this on code I have taken over, but I don't know what it does.

Upvotes: 1

Views: 755

Answers (1)

Marty
Marty

Reputation: 2808

Short story: for an experienced perl coded who knows what modules are: The Encode module is for converting perl strings to "some other" format (for which there are many sub-modules that define difference formats). Typically, it's used for converting to and from Unicode formats eg:

... to convert a string from Perl's internal format into ISO-8859-1, also known as Latin1:
    $octets = encode("iso-8859-1", $string);

decode is for going the other way, and from_to converts a string from one format to another in place;

from_to($octets, "iso-8859-1", "cp1250");

Long story: for someone who doesn't know what a module is/does: This is the classic way one uses code from elsewhere. "Elsewhere" usually means one of two possibilities - either;

  1. Code written "in-house" - ie: a part of your private application that a past developer has decided to factor out (presumably) because its applicable in several locations/applications; or
  2. Code written outside the organisation and made available publicly, typically from the Comprehensive Perl Archive Network - CPAN

Now, it's possible - but unlikely - that someone within your organization has created in-house code and co-incidentally used the same name for a module on CPAN so, if you check CPAN by searching for "Encode" - you can see that there is a module of that name - and that will almost certainly be what you are using. You can read about it here.

The qw/.../ stands for "quote words" and is a simple short hand for creating a list of strings; in this case it translates to ("encode", "decode", "from_to") which in turn is a specification of what parts of the Encode module you (or the original author) want.

You can read about those parts under the heading "Basic methods" on the documentation (or "POD") page I referred earlier. Don't be put off by the reference to "methods" - many modules (and it appears this one) are written in such a way that they support both an Object Oriented and functional interface. As a result, you will probably see direct calls to the three functions mentioned earlier as if they were written directly in the program itself.

Upvotes: 1

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