use statement in a conditional?

mangetsu has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
I'm modifying a test tool that uses a config file. At the moment the path to the file is hard coded and I want to be able to store it a avariable in a settings.pm file that contains evenvironmental settings.
The problem that this settings file may not be there, in which case I'd like to set the variable locally.
Is there a way to check if a file exists on disk and to put a use statement in conditional statement,so something like:

if (<check that the file exists>)
{
   use settings;
}
else
{
   $::CONFIGPATH = "C:\\configdir\\config.pm";
}
[download]

Is this complete gibberish or can I write someeing similar? Thanks

Edited by Chady -- added code tags and some line breaks.

Comment on use statement in a conditional? Download Code

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Re: use statement in a conditional? by imp (Priest) on Aug 18, 2006 at 13:48 UTC
You could use require instead, as it happens at runtime instead of compile time. The downside is that you need to know where the file is of course. `if (<check that the file exists>) { require 'settings.pm'; settings->import(); } else { $::CONFIGPATH = "C:\\configdir\\config.pm"; }` [download] Or you could use it in an eval, and run the else if it fails. `eval "use settings"; if ($@) { $::CONFIGPATH = "C:\\configdir\\config.pm"; }` [download]	[reply] [d/l] [select]
Re: use statement in a conditional? by davidrw (Prior) on Aug 18, 2006 at 13:49 UTC
See require for more info, but basically: `if( $someTest ){ my $class = 'Class::DBI'; eval "require $class"; die "Could not load '$class': $@" if $@; }` [download]	[reply] [d/l]
Re: use statement in a conditional? by ikegami (Patriarch) on Aug 18, 2006 at 15:49 UTC
Check out if (the module, not the flow control statement).	[reply]
Re^2: use statement in a conditional? by mangetsu (Novice) on Aug 18, 2006 at 17:06 UTC
It worked! Thanks for your help ^_^	[reply]
Re: use statement in a conditional? by mangetsu (Novice) on Aug 18, 2006 at 17:13 UTC
Uh just another quick question (in relation to the above) Is there a command to get the letter of the current drive? I've done it using getcwd and then matching the result against /.:/, but it seems like something for which there'd be a standard command. Thanks.	[reply]
Re^2: use statement in a conditional? by ikegami (Patriarch) on Aug 18, 2006 at 18:01 UTC
Re: use statement in a conditional? by davorg (Chancellor) on Aug 18, 2006 at 13:49 UTC
Wrap the "use" statement in a call to "eval" and then examine $@ for errors and take appropriate action. -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply]