I think you probably don't want the extra quotes. require "filename" means to require a filename, where require File::Name means to search @INC for a class (filename of File/Name.pm).

The usual reason behind the use of eval "require ..." is to make the contents of your variable into a bare word. The other reason, obviously, is to trap errors if the module is missing; or to execute the require at runtime instead of doing it before main execution.

You might also consider interpolation, so you don't have to explicitly concatenate like that.

eval "require $ARGV[0]"; die $@ if $@;
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I have assumed that "foo::try" actually is in another file. If it's in the same file, your require is never going to work. :)