Passing Placeholder Values into a Custom Snippet

Passing a value from a template placeholder into a custom snippet looks simple, but parser timing can make it fail in subtle ways. A classic example is sending [+introtext+] into a helper snippet and receiving either an empty value or the raw placeholder text back.

The original call

[[library_prev? &v='[+introtext+]']]

And a simplified snippet:

<?php
$replText = $v;
echo mb_strimwidth($replText, 0, 10, '...');

Why this breaks

The placeholder may not be ready at the time the snippet is parsed, or the quoting style may force the parser to treat it as a plain string rather than a resolved value.

Safer options

• generate the placeholder earlier in the request
• pass the raw field directly when possible
• do the trimming in the list/controller layer instead of chaining parser stages

[[library_prev? &v=`[*introtext*]`]]

Or better, prepare the short version before it reaches the snippet at all.

Rule of thumb

If a snippet depends on data created by another parser stage, check the order in which placeholders are populated. Most “empty parameter” bugs in Evolution CMS turn out to be parser-order bugs, not PHP bugs.