Why all the confusion to avoid use Debug;? It's a bad idea.

If I'd want to do it, I'd just create the sub in the main namespace and use :: in front of the sub name to look into that namespace.

package Debug;
sub ::dp { print "Moo!\n"; }

package test;
::dp;
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$ perl a.pl
Moo!
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If you're truly insane, you could take advantage of the fact that certain symbol default to the main namespace instead of the current namespace.

package main;
sub _ { print "Foo!\n" }
*% = sub { print "Bar!\n" };

package test;
_();
&%();
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$ perl a.pl
Foo!
Bar!
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Basically, any of the special symbol that's allowed as one-character var names (see perlvar) is can be used that way.

The catch is that except for _, they're not normally allowed as identifiers. You'll need to use the &name(...) syntax to call them, and you'll need to assign to the glob to define them.

But that's a bad idea.

• Modules can no longer be used independently of the main program, since they require a declaration of use Debug somewhere. This kind of defeats the point of modules: having a chunk of code that can be re-used in different contexts.
• Modules not written by you that include a sub-routine called dp now fail if they are loaded before Debug, since their dp will be over-written when Debug is loaded. This is going to be a nightmare to trace down, because when you put together a minimal test case for the module it is going to work fine.
• It makes maintenance hard, since there is no way for the maintenance programmer to know where dp is coming from.

The one second it takes to type 'use Debug;' is smaller by orders of magnitude than the amount of thinking and typing time required to implement even the most trivial module. If you are really worried about it, create a module skeleton that includes all the declarations you want and get your text editor to use it as a template for any new .pm files you create.

As others have pointed out, such a subversion of Perl's namespace management is a Bad Idea.

... this is the height of Laziness ...

It's more like employment insurance, for it will guarantee you (or those who follow you) many happy, billable hours of debugging.

... I figure with the saved keystrokes I might make up the development time by the end my programming life.

OTOH, after a few 3 AM debug sessions, you may want to end your programming life by your own hand!

If you don't do a use Debug in your module, how can you ensure that dp is available to your module? In other words, if this module is used by a different program, will this (hidden) prerequisite cause the next person to use your module to use your name in an unseemly context?

I figure with the saved keystrokes I might make up the development time by the end my programming life.

.... and replace it with the search time required to look for where the dp function is defined, or if you have the right one.