[z92]

My guess is that is the only reason.

Otherwise PHP itself is a template language. That is why you start it with <? tag.

Just keep short tags on [it's off by default on new installations but ON by default on all hosting sites] and you got a better template engine than smarty.

[jeltz]

PHP does not support HTML escaping and is therefor not secure by default. At least twig escapes HTML by default (I am not up to date with PHP so the others might too).

You do not want to type <?php echo htmlspecialchars($var, ENT_QUOTES) ?> every time you want to output data. (Yes, I know it could probably be written shorter but my PHP is rusty. My point still remains though, you have to remember to type it every time.)

[jiggy2011]

I think my solution back in the day was just to include the template files by running a function, something like showTemplate($templateName, $templateVars). The function takes an array as an arg so only these values are available to the template context (apart from the many global vars of course).

You can then run this entire array through htmlentities or htmlspecialchars before doing include().

[mcovey]

this is exactly how many modern frameworks do it. your response body is assembled and cached as your application executes, along with any variables it needs, and before the template is rendered the variables are sanitized.

[Mahn]

I think it's good this way, it forces the developer to think about the implications of escaped vs unescaped output. The way I see it, having htmlspecialchars/htmlentities applied automatically by a template engine is a close relative to the magic quotes; it abstracts something esential for the developer to know.