Re: Check if DBI is installed

You can check if DBI, or any other module, is available by trying to load it in an eval, and checking for an error (in $@):

eval { 
  require DBI;
  DBI->import;
  # ... as is documented in perlfunc under 'use',
  # this is same as 'use DBI', except done when the eval {}
  # is run, not when compiled (eval BLOCK catches only
  # runtime errors, eval STRING must be used to catch 
  # errors that  happen at compile time, but eval BLOCK 
  # is almost always better.)
};
if ($@) { # $@ has error from eval, if any.
  # Couldn't load DBI
} else {
  my $dbh = DBI->connect(...); 
  # Loaded DBI, okay.
}
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Comment on Re: Check if DBI is installed Download Code

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Re: Check if DBI is installed (eval to check module is installed) by mandog (Curate) on Sep 02, 2001 at 10:18 UTC
autouse apparently has the same effect as require / import `use warnings ; use strict; use autouse 'foo'; # perldoc autouse eval {foo::not_here();}; # perldoc -f eval my $we_care=0; warn $@ if ($@ && $we_care);` [download] Update: changed `use autouse foo` to `use autouse 'foo'` (thanks tachyon) --mandog	[reply] [d/l] [select]
Re: Re: Check if DBI is installed (eval to check module is installed) by tachyon (Chancellor) on Sep 02, 2001 at 16:19 UTC
C:\>type test.pl use warnings ; use strict; use autouse foo; # perldoc autouse eval {foo::not_here();}; # perldoc -f eval my $we_care=0; warn $@ if ($@ && $we_care); C:\>perl test.pl Bareword "foo" not allowed while "strict subs" in use at test.pl line +5. Execution of test.pl aborted due to compilation errors. C:\>type test.pl use warnings ; use strict; use autouse 'foo'; # perldoc autouse eval {foo::not_here();}; # perldoc -f eval my $we_care=0; warn $@ if ($@ && $we_care); C:\>perl test.pl C:\> C:\>type test.pl use warnings ; use strict; use autouse 'foo'; # perldoc autouse eval {foo::not_here();}; # perldoc -f eval warn $@ if $@; C:\>perl test.pl Undefined subroutine &foo::not_here called at test.pl line 6. C:\> [download] I presume you mean something like the last example? cheers tachyon s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print	[reply] [d/l]