in reply to Re: Re: 'used once' during perl -c
in thread 'used once' during perl -c

I'm afriad I'm unable to duplicate that here. I get the warning both when I -c it, and when I run it which, as far I as I know, is the correct behavior. This is with both ActiveState perl, and Cygwin perl.

Perhaps you can post the code that's causes that behavior? You're not on 5.8.0, are you? Both of my perl's are 5.6.1. *shrug*

(Output from my test below) 

[johnsca@CORY tmp]$ cat tst
#!/usr/bin/perl

use warnings;
use strict;

sub foo { return 3 }

*blah = \&foo;
[johnsca@CORY tmp]$ perl -c tst
Name "main::blah" used only once: possible typo at tst line 8.
tst syntax OK
[johnsca@CORY tmp]$ ./tst
Name "main::blah" used only once: possible typo at ./tst line 8.
[johnsca@CORY tmp]$ perl -v

This is perl, v5.6.1 built for cygwin-multi

Copyright 1987-2001, Larry Wall

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using `man perl' or `perldoc perl'.  If you have access to
+ the
Internet, point your browser at http://www.perl.com/, the Perl Home Pa
+ge.

[johnsca@CORY tmp]$ /win2k/Perl/bin/perl tst
Name "main::blah" used only once: possible typo at tst line 8.
[johnsca@CORY tmp]$ /win2k/Perl/bin/perl -v 

This is perl, v5.6.1 built for MSWin32-x86-multi-thread
(with 1 registered patch, see perl -V for more detail)

Copyright 1987-2001, Larry Wall

Binary build 633 provided by ActiveState Corp. http://www.ActiveState.
+com
Built 21:33:05 Jun 17 2002


Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using `man perl' or `perldoc perl'.  If you have access to
+ the
Internet, point your browser at http://www.perl.com/, the Perl Home Pa
+ge.

[download]

bbfu
Black flowers blossum
Fearless on my breath

Replies are listed 'Best First'.
Re: (bbfu) (warning only during -c) Re3: 'used once' during perl -c
by John M. Dlugosz (Monsignor) on Nov 04, 2002 at 20:18 UTC
    Hmm... a guess: my code is in a .pm file. Perhaps Perl automatically enters another "use" of import when doing a use of a module. Then the issue isn't -c or not, but main-program or not.

[reply]
[d/l]

      From your /msg, I've been able to put together the following: 

      [johnsca@CORY tmp]$ cat tst.pm
#!/usr/bin/perl

package tst;

use warnings;
use strict;


*import = \&foo;

sub foo {
  print "Import foo\n";
}

1;
[johnsca@CORY tmp]$ cat tst.pl
#!/usr/bin/perl

use warnings;
use strict;

use lib '.';
use tst;
[johnsca@CORY tmp]$ perl -c tst.pm
Name "tst::import" used only once: possible typo at tst.pm line 9.
tst.pm syntax OK
[johnsca@CORY tmp]$ perl -c tst.pl
Import foo
tst syntax OK
[johnsca@CORY tmp]$ perl tst.pm
Name "tst::import" used only once: possible typo at tst.pm line 9.
[johnsca@CORY tmp]$ perl tst.pl
Import foo

      [download]

      From this, I think makes sense. The warning when running perl -c tst.pm (and perl tst.pm) is appropriate, as import is only used once, when you consider only tst.pm. However, once you throw tst.pl into the mix, you get another (implicit) use of *tst::import via the use, as you said, which silences the warning. This makes sense as, according to the docs for use: 

      It is exactly equivalent to

    BEGIN { require Module; import Module LIST; }

except that Module must be a bareword.

      To prevent the warning when checking tst.pm, you can locally disable warnings, as I suggested before, or you can add another (no-op) reference to *import. In the code below, I use use vars qw/*import/; because our doesn't seem to like typeglobs. :) <Update>Though our $import; seems to get rid of the error just fine.</Update> 

      [johnsca@CORY tmp]$ cat tst.pm
#!/usr/bin/perl

package tst;

use warnings;
use strict;


use vars qw/*import/;
# or: *import = *import;

*import = \&foo;

sub foo {
  print "Import foo\n";
}

1;
[johnsca@CORY tmp]$ perl -c tst.pm
tst.pm syntax OK

      [download]

      bbfu
      Black flowers blossum
      Fearless on my breath

[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom