In Perl what is the difference between a pm Perl module and pl Perl script file

Question

What is the Difference between  pm  Perl module  and  pl  Perl script  file   Please also tell me why we return 1 from file  If return 2 or anything else  it s not generating any error  so why do we return 1 from Perl module

User · Answer

A  pl is a single script   In  pm  Perl Module  you have functions that you can use from other Perl scripts      A Perl module is a self-contained piece of Perl code that can be used by a Perl program or by other Perl modules  It is conceptually similar to a C link library  or a C   class

User · Answer

At the very core  the file extension you use makes no difference as to how perl interprets those files  However  putting modules in  pm files following a certain directory structure that follows the package name provides a convenience  So  if you have a module Example  Plot  FourD and you put it in a directory Example Plot FourD pm in a path in your  INC  then use and require will do the right thing when given the package name as in use Example  Plot  FourD   The file must return true as the last statement to indicate successful execution of any initialization code  so it s customary to end such a file with 1   unless you re sure it ll return true otherwise  But it s better just to put the 1   in case you add more statements  If EXPR is a bareword  the require assumes a  quot  pm quot  extension and replaces  quot    quot  with  quot   quot  in the filename for you  to make it easy to load standard modules  This form of loading of modules does not risk altering your namespace   All use does is to figure out the filename from the package name provided  require it in a BEGIN block and invoke import on the package  There is nothing preventing you from not using use but taking those steps manually  For example  below I put the Example  Plot  FourD package in a file called t pl  loaded it in a script in file s pl  C  Temp gt  cat t pl package Example  Plot  FourD   use strict  use warnings   sub new   bless      gt  shift    sub something   print  quot something n quot      quot Example  Plot  FourD quot   C  Temp gt  cat s pl    usr bin perl use strict  use warnings   BEGIN       require  t pl      my  p   Example  Plot  FourD- gt new   p- gt something    C  Temp gt  s something  This example shows that module files do not have to end in 1  any true value will do

[perl] In Perl, what is the difference between a .pm (Perl module) and .pl (Perl script) file?

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