[Canberra-pm] how to tell if a library is available?

[Kim Holburn]

OK, thanks, that's good but I have a problem.  Maybe this is a dumb  
question but if I test for this and in one branch of the test I invoke  
the library with a use statement it works if the library is present  
but not if it's not there:

eval "use Text::Autoformat" ;
if (!$@) {
   use Text::Autoformat ;
   ....

Can't locate Text/Autoformat.pm in @INC (@INC contains: ...
) at script.pl line 316.
BEGIN failed--compilation aborted at script.pl line 316.


Am I mistaken here?  Do I need to have a "use" statement in addition  
to the eval?

If I don't have the use statement I get lots of other errors (using -w).

Kim

On 2008/Jun/14, at 11:40 AM, Jacinta Richardson wrote:

> Kim Holburn wrote:
>> I have a script which could use a library (Text::Autoformat) if  
>> it's  available in the current libs or if it's in the directory the  
>> script  is in.  I'd like a simple test to tell this before I either  
>> try and  use it or use a work-around.
>> Is there any simple test for this?
>
> Try using it with a string eval and then check $@.  For example:
>
> 	eval "use Foo;";
> 	if($@) {
> 	        print "Could not find Foo\n";
> 	}
>
> 	eval "use Bar;";
> 	if($@) {
> 	        print "Could not find Bar: $@\n";
> 	}
>
> 	print "Program completed\n";
>
>
> with Foo.pm being:
>
> 	package Foo;
>
> 	print "Foo!\n";
>
> 	1;
>
> yields:
>
> 	jarich at teddybear:/tmp$ perl test.pl
> 	Foo!
> 	Could not find Bar: Can't locate Bar.pm in @INC (@INC contains:
> 	/etc/perl /usr/local/lib/perl/5.8.8 /usr/local/share/perl/5.8.8 	
> 	/usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.8
> 	/usr/share/perl/5.8 /usr/local/lib/site_perl
> 	/usr/local/lib/perl/5.8.4 /usr/local/share/perl/5.8.4 .) at
> 	(eval 2) line 1.
> 	BEGIN failed--compilation aborted at (eval 2) line 1.
>
> 	Program completed
>
> If you choose to try to use a second module upon failing the first,  
> remember to save $@ if you ever intend to use it:
>
> 	eval "use Foo;";
> 	if(my $E = $@) {
> 	        print "Could not find Foo, trying Bar\n";
> 		eval "use Bar;";
> 		# $@ has now changed!
> 	}
>
> I hope this helps.
>
> 	J

--
Kim Holburn
IT Network & Security Consultant
Ph: +39 06 855 4294  M: +39 3494957443
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Democracy imposed from without is the severest form of tyranny.
                           -- Lloyd Biggle, Jr. Analog, Apr 1961