Is there any context in which a string containing ONLY whitespace tests false?

Here's the situation:
The HTML output page of a script prints, "Hello, $name!" to greet the visitor.
First the script imports the user's info file that contains their name, among other things, via require.
If the user file does not contain a $name variable, as in the case of first-time visitors, & the output page will say, "Hello, Guest!".
require $user_file_path;
$name = $nick_name || "$salutation $last_name";
$name ||= 'Guest';

[download]
The problem is in the case that there's no $nick_name, $salutation, or $last_name variables.
So $name gets assigned " " in the second line, and line 3 can't change it to 'Guest' because " " tests true.
The output page ends up reading, "Hello, !"

I know I could use a regexp or any number of other ways to get rid of that pesky whitespace string, but I'm a stubborn guy who doesn't want to add an extra line of code in there.

What I want is a module or something that I can import which will make it so any string containing only whitespace tests false. I've never written a module and I don't even know if what I want is possible to do, so I need some friendly guideance.

Many thanks!

In reply to Truth & Whitespace by Anonymous Monk

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