Your two ways of testing undef don't actually do the same thing.
if defined $var will execute your statement if $var is defined. unless $var eq undef will execute your statement if $var is undef, the empty string, or something else that will stringify to the empty string. Try the following code snippet to see for yourself:
my $var = undef;
print "Undefined!\n" if $var eq undef;
$var = '';
print "Undefined again!\n" if $var eq undef;
This happens because the "eq" operator stringifies both of its arguments, and undef stringifies to the empty string.
The warning doesn't exist just to critique your syntax... it's warning you of a danger that your code might not be doing exactly what you think it is.
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|