«

Hi, friends,

Although I read several books before posting this, I still don't know how to declare a scalar in "common.pl" and use it directly in "script.pl":

common.pl

$root = "/root";


script.pl

require "common.pl"; # this line works
print "$root"; # Global symbol "$root" requires explicit package name

PS: I habitually use the -wT switch

Regent

Regent wrote:
> Although I read several books before posting this,

Those cannot have been Perl books...

> I still don't know how to declare a scalar in "common.pl" and use
> it directly in "script.pl":
>
> common.pl
>
> $root = "/root";
>
>
> script.pl
>
> require "common.pl"; # this line works
> print "$root"; # Global symbol "$root" requires
> # explicit package name
>
> PS: I habitually use the -wT switch

Good. Since you get that error message, you are obviously using
strictures too, which is also good.

These are two ways to do what you want:

our $root; # declares $root as a package global
require "common.pl";
print $root;

or

require "common.pl";
print $main::root; # explicit package name

(There is no need to quote the variable in the print statement.)

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl

On Mon, 29 Dec 2003 10:26:40 +0800, Regent <> wrote:
> Hi, friends,
>
> Although I read several books before posting this, I still don't know
> how to declare a scalar in "common.pl" and use it directly in
> "script.pl":

Typically require inserts the contents of the required script at the point
of the require statement. However, I noticed that if I used "my $root",
it only seemed to be in scope in the required script, and was
uninitialized in main script.

> common.pl
>
> $root = "/root";
>
>
> script.pl
>
> require "common.pl"; # this line works
> print "$root"; # Global symbol "$root" requires explicit package name
>
> PS: I habitually use the -wT switch
>
> Regent
>

If I just used -w switch (and put a newline in print "$root\n",
I got:

Name "main::root" used only once: possible typo at ./mytest line 3.
/root

Inserting a use vars line got rid of the warning:

use vars ('$root');
require "common.pl";
print "$root\n"

If I used -wT, "." (current dir) was apparently excluded from @INC, so I
had to use a full path to common.pl (same output).

Tested in perl v5.6.1 built for i586-linux and v5.8.0 built for
i586-linux-thread-multi

--
David Efflandt - All spam ignored http://www.de-srv.com/
PS: All mail referencing [1-9]63\.(com|net) is automatically dropped due
to excessive uncontrolled spam.

David Efflandt <> wrote:

> However, I noticed that if I used "my $root",
> it only seemed to be in scope in the required script, and was
> uninitialized in main script.


That is what my() is _supposed to do.


perldoc -f my

... local (lexically) to the enclosing block, file ...


$root will only be in the scope of the "required file" since
my() variables can never cross file boundaries.


--
Tad McClellan SGML consulting
Perl programming
Fort Worth, Texas

---------------------
Mon, 29 Dec 2003 03:58:37 +0100 £¬Gunnar Hjalmarsson wrote:
>Those cannot have been Perl books...

Well, those were books ABOUT Perl. The Perl books (to which I believe you refer) seem to discuss principles rather than specific problems, but I'm not much more than a newbie (

>These are two ways to do what you want:
>
> our $root; # declares $root as a package global

You mean in common.pl? I put this line in common.pl, but it seemed I had also to declare $root in script.pl, otherwise I still got a "Global symbol "$root" requires explicit package name" error. Then I tried "my $root;" in script.pl, but got a "Use of uninitialized value", though I had already expected this error msg. The problem seems to be how do declare $root AGAIN in script.pl, which sounds weird to me

> require "common.pl";
> print $root;
>
>or
>
> require "common.pl";
> print $main::root; # explicit package name

This worked! Thanks indeed, but what does $main here mean? "::" means the use of modules to me. BTW, $main::root appears to be a somewhat clumsy

>
>(There is no need to quote the variable in the print statement.)
>
>--
>Gunnar Hjalmarsson
>Email: http://www.gunnar.cc/cgi-bin/contact.pl
>

Regent

Regent wrote:
> Gunnar Hjalmarsson wrote:
>>These are two ways to do what you want:
>>
>> our $root; # declares $root as a package global
>
> You mean in common.pl?

No, I mean in script.pl. Both my suggestions were intended for
script.pl, while keeping common.pl as it is.

>> require "common.pl";
>> print $main::root; # explicit package name
>
> This worked! Thanks indeed, but what does $main here mean?

$main::root means the global variable $root in package main.

> "::" means the use of modules to me.

When something begins with a '$' character, it's most likely a
variable. You'd better do some reading:

http://www.perldoc.com/perl5.8.0/pod/perlmod.html

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl

------------------------
Tue, 30 Dec 2003 01:58:53 +0100 £¬Gunnar Hjalmarsson wrote:
>Regent wrote:
>> Gunnar Hjalmarsson wrote:
>>>These are two ways to do what you want:
>>>
>>> our $root; # declares $root as a package global
>>
>> You mean in common.pl?
>
>No, I mean in script.pl. Both my suggestions were intended for
>script.pl, while keeping common.pl as it is.

Okay, I see. If I use this method, I must declare all scalars in script.pl like this, right?

>>> require "common.pl";
>>> print $main::root; # explicit package name
>>
>> This worked! Thanks indeed, but what does $main here mean?
>
>$main::root means the global variable $root in package main.
>
>> "::" means the use of modules to me.
>
>When something begins with a '$' character, it's most likely a
>variable. You'd better do some reading:

Yup, I know the '$' well, but never used "::" in this way

> http://www.perldoc.com/perl5.8.0/pod/perlmod.html
>
>--
>Gunnar Hjalmarsson
>Email: http://www.gunnar.cc/cgi-bin/contact.pl
>

------------------------
Regent

Regent wrote:
> Gunnar Hjalmarsson wrote:
>> Regent wrote:
>>> Gunnar Hjalmarsson wrote:
>>>>
>>>> our $root; # declares $root as a package global
>>>
>>> You mean in common.pl?
>>
>> No, I mean in script.pl. Both my suggestions were intended for
>> script.pl, while keeping common.pl as it is.
>
> Okay, I see. If I use this method, I must declare all scalars in
> script.pl like this, right?

Only those scalars you require from other files that way. Other
variables should preferrably be declared with my().

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl

------------------------
Mon, 29 Dec 2003 03:53:17 +0000 (UTC) £¬David Efflandt wrote:
>If I just used -w switch (and put a newline in print "$root\n",
>I got:
>
>Name "main::root" used only once: possible typo at ./mytest line 3.
>/root
>
>Inserting a use vars line got rid of the warning:
>
>use vars ('$root');
>require "common.pl";
>print "$root\n"
>
>If I used -wT, "." (current dir) was apparently excluded from @INC, so I
>had to use a full path to common.pl (same output).

Yeah, this is a problem. If common.pl isn't in one of the paths already indicated in @INC, I must specify its full path in every script, right?

>Tested in perl v5.6.1 built for i586-linux and v5.8.0 built for
>i586-linux-thread-multi
>
>--
>David Efflandt - All spam ignored http://www.de-srv.com/
>PS: All mail referencing [1-9]63\.(com|net) is automatically dropped due
>to excessive uncontrolled spam.

------------------------
Regent

or you can include it in the @INC path

use lib('PATH','ANOTHERPATH');

J

"Regent" <> wrote in message news:bsqli7$6sh$...
>
> ------------------------
> Mon, 29 Dec 2003 03:53:17 +0000 (UTC) £¬David Efflandt wrote:
> >If I just used -w switch (and put a newline in print "$root\n",
> >I got:
> >
> >Name "main::root" used only once: possible typo at ./mytest line 3.
> >/root
> >
> >Inserting a use vars line got rid of the warning:
> >
> >use vars ('$root');
> >require "common.pl";
> >print "$root\n"
> >
> >If I used -wT, "." (current dir) was apparently excluded from @INC, so I
> >had to use a full path to common.pl (same output).
>
> Yeah, this is a problem. If common.pl isn't in one of the paths already indicated in @INC, I must specify its full path in every script, right?
>
> >Tested in perl v5.6.1 built for i586-linux and v5.8.0 built for
> >i586-linux-thread-multi
> >
> >--
> >David Efflandt - All spam ignored http://www.de-srv.com/
> >PS: All mail referencing [1-9]63\.(com|net) is automatically dropped due
> >to excessive uncontrolled spam.
>
> ------------------------
> Regent
>
>


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