undefined constants FALSEOR and FALFALSEORFALSE

Question

In a template I was working on recently, I started to get PHP Notices about undefined constants FALSEOR and FALFALSEORFALSE:

A PHP Error was encountered
Severity: Notice
Message: Use of undefined constant FALSEOR - assumed 'FALSEOR'
Filename: libraries/Functions.php(683) : eval()'d code
Line Number: 205

[and]

A PHP Error was encountered
Severity: Notice
Message: Use of undefined constant FALFALSEEORFALSE - assumed 'FALFALSEEORFALSE'
Filename: libraries/Functions.php(683) : eval()'d code
Line Number: 260

The template code that generated these messages was:

{if STYLE}
    <tr>
        <td>Style</td>
        <td>{STYLE}</td>
    </tr>
{/if}

{if YEARBUILT}
    <tr>
        <td>Year Built</td>
        <td>{YEARBUILT} {if YEARBUILTSRC}({YEARBUILTSRC}){/if}</td>
    </tr>
{/if}

The variable names in all caps are variables provided by a plug-in. It is possible that they may have empty values, but I haven't been able to produce a case where any would be undefined [in the array consumed by TMPL->parse_variables() in the plugin].

I'm stumped as to why they're being parsed as PHP constants... And even so, I don't see where the strings 'FALSEOR' or 'FALFALSEORFALSE' are being created. Those strings don't appear anywhere in the EE source [that I can find], and none of the template variables are so named.

Should I report this as a bug? Has anybody seen something like this before?

Answer 1

PHP has four values when it evaluates an if condition, true, truthy, false, and falsey.

http://www.phabricator.com/docs/phabricator/article/PHP_Pitfalls.html

Depending on what you're getting back from your add-on, or the add-on's datasource (especially if the data from the source is inconsistent) PHP's conditional logic may act strange if you don't check the value explicitly (ex: STYLE != '').

Also since it sounds like you'll be checking for empty strings. I might take an additional step and fashion your IF statements like this:

{if "{STYLE}" != ""}
   ...
{/if}

This will ensure that "STYLE" is always interpreted as a string rather than being evaluated as an object or PHP reserved value