I made myself a custom PERL module and it works when called by a script in the same directory, but not from outside the directory for somewhat obvious reasons. How do I use the module without installing it? eg:
use 5.012;
use warnings;
use Y:/my/dir/to/module.pm;
use lib 'Y:/my/dir/to';
use module; # BAD name for module, lowercase is reserved for pragmas...
If you only have one module, instead of using lib, you can do this :
BEGIN {
unshift #INC,"dir";
##INC is the directory list, where perl searches for .pm files
}
use Foo::Bar; #dir/Foo/Bar.pm
#or
do "dir/Foo/Bar.pm"; #perldoc -f do
Related
I have made my own perl modules(pm files),named test.pm
package test;
use Exporter;
use strict;
use File::Basename qw(basename dirname);
use Cwd qw(abs_path);
use File::Path qw(make_path);
use FindBin qw($Bin $Script);
BEGIN {
our #ISA = qw(Exporter);
our #EXPORT = qw(mkdirOrDie);
our $VERSION = 1.0;
}
sub mkdirOrDie
{
my ($dir) = #_ ;
if(!-d $dir){
make_path($dir);
$dir=abs_path($dir);
# timeLog("Directory Created: $dir");
}
}
and I tried to install this module as follows,
h2xs -AX -n test
perl Makefile.PL
make
make install
there is no error,and I copy the test.pm to /usr/lib64/perl5/5.10.0/,but when i call sub function using test, an error has occurred,
Undefined subroutine &main::mkdirOrDie called at /to/my/path/main.pl line 92
is there something i ignored?
It's unclear at which point things started to go wrong for you.
Firstly, test.pm is a bad name for a Perl module. Perl modules should have names that begin with upper case letters (and Test.pm is already taken).
You should run h2xs before writing your code - as it generates a module skeleton for you fill in. I hope it hasn't overwritten your code with an almost empty file! It's also worth noting that most people stopped using h2xs many years ago. These days we have tools like Module::Starter.
Then, running, make install (which you need to do with root permissions - so usually with sudo) is what installs your module into the system libraries. There should be no need to run that cp command afterwards.
As for why your code doesn't find the module, there are many possible reasons. Are you using Perl 5.10 or do you have other Perl versions installed? What does the code look like that you are trying to use? Does test.pm still include the code you think it does?
Need more information to be much help here.
I want to create a module in Perl. The below code is not working properly. I want to create a word count module and I want to reuse it further. Can anyone help me out to create this module? This is my first attempt to create a module so kindly help me out.
package My::count
use Exporter qw(import);
our #Export_ok = qw(line_count);
sub line_count {
my $line = #_;
return $line;
}
I saved the above code in count.pm
use My::count qw(line_count);
open INPUT, "<filename.txt";
$line++;
print line count is $line \n";
I saved the above script in .pi extension.
This code is showing error when I run it on an Ubuntu platform. Kindly help me to fix this errors.
Perl scripts are stored with .pl extension. As you say use My::count qw(line_count); Perl tries to search the modules from the directories stored in #INC variable. You can run it with the -I flag to specify the directory to search the custom packages. Refer to this question for more info.
By convention Perl packages usually have a capitalized first letter, so My::count is more in keeping with convention if you call it package My::Count;. Typically lower-cased module names are reserved for pragmas such as 'strict' and 'warnings'. So go ahead and change the name to My::Count.
Next, save the module in a path such as lib/My/Count.pm. lib is by convention as well.
Then you have to tell your script where to find package My::Count.
Let's assume you're storing your module and your executable like this:
~/project/lib/My/Count.pm
~/project/bin/count.pl
Notice I also used a .pl extension for the executable. This is another convention. Often on Unix-like systems people omit the .pl extension altogether.
Finally, in your count.pl file you need to tell perl where to find the library. Often that is done like this:
#!/usr/bin/env perl
use strict;
use warnings;
use FindBin qw($Bin);
use lib "$Bin/../lib";
use My::Count 'line_count';
# The rest goes here...
As you can see, we're using FindBin to locate where the executable is stored, and then telling perl that it should look (among other places) in the lib folder stored in a relative location to the executable.
Naturally, as this is Perl, this is not the only way to do it. But it's one common idiom.
You need to move your count.pm file into a directory called My. So you have the following.
./count.pl
./My/count.pm
I've got a collection of Perl scripts which use the FindBin module. There are some data files which the scripts use, and are expecting to find them in $FindBin::Bin/../share/somedir/. I'm customizing the installation so those files now exist is /some/other/share/dir/. Is there any way to customize the behaviour of FindBin with something like, say, an environment variable?
I don't think you can solve this problem with FindBin module, because it's designed to solve particular problem: locate directory of original perl script.
You should implement your own module to getting configuration parameters. This can look like:
package MyConfig;
use strict; use warnings;
use FindBin;
sub get_data_folder {
return ($ENV{'DEV_ENVIROMENT'} ? ## create this variable in your development
$FindBin::Bin."/../share/somedir/" :
"/some/other/share/dir/"
);
}
1;
This will allow you to control all your configuration path in one place. But you'll need to change exists code.
My scripts are getting too long. How do I split my code (procedural subs) into multiple Perl files and tell the interpreter to make sense of them?
Kind of like:
# -> main.pl
#include "foo.pl"
say_hello();
and:
# -> foo.pl
sub say_hello {print "hello!"}
What you want to do is create one or more modules. Start by looking over perlmod, especially the Perl Modules section.
Since you say you're writing procedural code, you'll want to export functions from your modules. The traditional way to do that is to use Exporter (which comes with Perl), although Sub::Exporter is a newer CPAN module that allows for some nice things. (See also its Sub::Exporter::Tutorial for an introduction to exporting functions.)
Modules can be placed in any of the directories listed in the #INC variable. Try perl -V to get a list. You can also use lib to add directories at runtime. One trick is to use the FindBin module to find the location of your script, and then add a directory relative to that:
use FindBin; # Suppose my script is /home/foo/bin/main.pl
use lib "$FindBin::Bin/lib"; # Add /home/foo/bin/lib to search path
Your sample code, converted to a module:
In main.pl:
#! /usr/bin/perl
use strict;
use warnings;
use Foo;
say_hello();
In Foo.pm:
package Foo;
use strict;
use warnings;
use Exporter 'import';
our $VERSION = '1.00';
our #EXPORT = qw(say_hello);
sub say_hello {print "hello!"}
1; # A module must end with a true value or "use" will report an error
I think you may be looking for do? http://perldoc.perl.org/functions/do.html
put it in the same folder as your class and add use ClassName to the top of the calling file.
Also check the Perl OOP tutorial.
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?
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 ".pm" extension and replaces "::" with "/" 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> cat t.pl
package Example::Plot::FourD;
use strict; use warnings;
sub new { bless {} => shift }
sub something { print "something\n" }
"Example::Plot::FourD"
C:\Temp> cat s.pl
#!/usr/bin/perl
use strict; use warnings;
BEGIN {
require 't.pl';
}
my $p = Example::Plot::FourD->new;
$p->something;
C:\Temp> s
something
This example shows that module files do not have to end in 1, any true value will do.
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.