I have a simple module called My.pm: 
package My;
print "Loading...\n";
sub Run { print "Running\n" }

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If I were to try to load, remove it from the symbol table, and reload it (as done by Module::Refresh::refresh_module): 

use My;
delete $INC{"My.pm"};
undef &My::Run;            # Why do this?!
delete $My::{Run};
require My;
eval "My::Run()";
My::Run();

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Then I'd see output like this: 

Loading...
Loading...
Running
Undefined subroutine &My::Run called at -e line 1.

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Question 1: why does the undef statement makes the next require fail?

I can get around that by simply removing that line: 

use My;
delete $INC{"My.pm"};
delete $My::{Run};
require My;
eval "My::Run()";
My::Run();

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Then I'd see output like this: 
Loading...
Loading...
Running
Running

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Now to the interesting part: 

use My;
<STDIN>;                       # NEW
delete $INC{"My.pm"};
delete $My::{Run};
require My;
eval "My::Run()";
My::Run();

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During the pause, update My.pm to have a different output message.

Then press enter to continue: 

Loading...

Loading...
Running again
Running

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One step further, during the pause, remove the Run function and observe: 

Loading...

Loading...
Running again

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Question 2: How to reload a module without having to use an eval (like eval "My::Run()")

Thanks,

~Tim

In reply to Refresh a Module by Timka

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