why does perl's Module::Load::Conditional::check_install find uninstalled module? - perl

Question

--> perl -v
This is perl 5, version 24, subversion 0 (v5.24.0) built for x86_64-linux
I'm trying to conditionally load a perl module if it's installed using...
#!/usr/bin/env perl
use strict;
use Module::Load::Conditional qw[can_load check_install requires];
if(check_install( module => 'dvm_common')) {
use dvm_common;
print "Looks like dvm_common is installed, so it was loaded.\n";
} else {
print "Looks like dvm_common is not installed.\n";
}
exit;
Won't compile, complains about missing module...
--> perl -c ./mod_load_cond_test.pl
Can't locate dvm_common.pm in #INC (you may need to install the dvm_common module) (#INC contains: etc... .) at ./mod_load_cond_test.pl line 6.
BEGIN failed--compilation aborted at ./mod_load_cond_test.pl line 6.
I thought the whole point of using this was to test for the existence of the module before loading it ?

Answer 1

use is a compile-time statement, so the interpreter will load a module immediately when it it passing through the source and encounters a use statement, as if you had written
BEGIN { require Module; Module->import }
To load a module at run-time, you can use require
if(check_install( module => 'dvm_common')) {
require dvm_common;
dvm_common->can("import") && dvm_common->import; # optional
...
or string eval:
if(check_install( module => 'dvm_common')) {
eval "use dvm_common;1" or die $#;
...