spiros sent an email (Tue, Feb 12, 2013 at 5:04 PM) stating:

and on a test install with Semantic Result Formats version 1.9 alpha with MW
1.19.3 I get:

Fatal error: Class 'SMW\ResultPrinter' not found in
...extensions/SemanticResultFormats/formats/gallery/Gallery.php on line 38

I use:
PHP 5.3.21 (apache2handler)
MySQL 5.1.68-cll

Problem will only occur for MW < 1.20, leaving only 1.19.x as we will no longer support 1.18 anyway.

It is also specific to used PHP version. See https://bugs.php.net/bug.php?id=50731

Not sure what versions are affected exactly, though I know it works on 5.3.6 and later but is broken with 5.3.2.

Considering that PHP 5.3.x is at 5.3.21, and that only MW 1.19.x is affected, this might not be that critical. If we decide to not support, we should put in a check and provide a clear error when not compatible.