source: branches/rel/data/module/Smarty/FAQ @ 12157

QUESTION INDEX
--------------

GENERAL

Q: What is Smarty?
Q: What's the difference between Smarty and other template engines?
Q: What do you mean "Compiled PHP Scripts" ?
Q: Why can't I just use PHPA (http://php-accelerator.co.uk) or Zend Cache?
Q: Why does smarty have a built in cache? Wouldn't it be better to handle this
   in a separate class?
Q: Is Smarty faster than <insert other PHP template engine>?
Q: How can I be sure to get the best performance from Smarty?
Q: Do you have a mailing list?
Q: Can you change the mailing list so reply-to sends to the list and not the
   user?

TROUBLESHOOTING

Q: Smarty doesn't work.
Q: I get the following error when running Smarty:
   Warning:  Smarty error: problem creating directory "templates_c/239/239105369"
   in /path/to/Smarty.class.php on line 542
Q: I get the following error when running Smarty:
   Warning: Wrong parameter count for preg_replace() in
   Smarty.class.php on line 371
Q: I get this error when passing variables to {include}:
   Fatal error: Call to undefined function: get_defined_vars() in
   /path/to/Smarty/templates_c/index.tpl.php on line 8
Q: I get PHP errors in my {if} tag logic.
Q: I'm changing my php code and/or templates, and my results are not getting
   updated.
Q: I'm running Windows 2000 and I get blank content. My compiled PHP files are
   also zero length.
Q: The template goes into an infinite loop when I include included templates
   that pass local variables
Q: Javascript is causing Smarty errors in my templates.
Q: I get "SAFE MODE Restriction in effect. ..."-errors when running smarty.

MISC

Q: Can I use Macromedia's Dreamweaver to edit my templates?
Q: Dreamweaver is urlencoding the template delimiters when they are in a SRC or
   HREF link. How do I get around this?

HOWTO

Q: How do I generate different cache files per template based on arguments
   passed to the page?
Q: How do I pass a template variable as a parameter? {function param={$varname}}
   does not work.
Q: How do I include cached template(s) within a non-cached template?


GENERAL
-------

Q: What is Smarty?
A: Smarty is a template engine for PHP... but be aware this isn't just another
   PHP template engine. It's much more than that.

Q: What's the difference between Smarty and other template engines?
A: Most other template engines for PHP provide basic variable substitution and
   dynamic block functionality. Smarty takes a step further to be a "smart"
   template engine, adding features such as configuration files, template
   functions, variable modifiers (see the docs!) and making all of this
   functionality as easy as possible to use for both programmers and template
   designers. Smarty also compiles the templates into PHP scripts, eliminating
   the need to parse the templates on every invocation, making Smarty extremely
   scalable and manageable for large application needs.

Q: What do you mean "Compiled PHP Scripts" ?
A: Smarty reads the template files and creates PHP scripts from them. Once
   these PHP scripts are created, Smarty executes these, never having to parse
   the template files again. If you change a template file, Smarty will
   recreate the PHP script for it. All this is done automatically by Smarty.
   Template designers never need to mess with the generated PHP scripts or even
   know of their existance. (NOTE: you can turn off this compile checking step
   in Smarty for increased performance.)

Q: Why can't I just use PHPA (http://php-accelerator.co.uk) or Zend Cache?
A: You certainly can, and we highly recommend it! What PHPA does is caches
   compiled bytecode of your PHP scripts in shared memory or in a file. This
   speeds up server response and saves the compilation step. Smarty creates PHP
   scripts, which PHPA will cache nicely. Now, Smarty's built-in cache is
   something completely different. It caches the _output_ of the template
   contents. For example, if you have a template that requires several database
   queries, Smarty can cache this output, saving the need to call the database
   every time. Smarty and PHPA (or Zend Cache) complement each other nicely. If
   performance is of the utmost importance, we would recommend using one of
   these with any PHP application, using Smarty or not. As you can see in the
   benchmarks, Smartys performance _really_ excels in combination with a PHP
   accelerator.

Q: Why does Smarty have a built in cache? Wouldn't it be better to handle this
   in a separate class?
A: Smarty's caching functionality is tightly integrated with the template
   engine, making it quite a bit more flexible than a simple caching wrapper.
   For instance, you can cache select portions of a template page. Let's say
   you have a polling box on your site. With Smarty, you can leave the poll
   dynamic and cache the rest of the page. You can also pass templates
   multiple cache ids, meaning that a template can have several caches
   depending on URL, cookies, etc.

Q: Is Smarty faster than <insert other PHP template engine>?
A: See the benchmark page for some performance comparisons. Smarty's approach
   to templates is a bit different from some languages: it compiles templates
   into PHP scripts instead of parsing them on each invocation. This usually
   results in great performance gains, especially with complex templates.
   Coupled with the built-in caching of Smarty templates, the performance is
   outstanding.

Q: How can I be sure to get the best performance from Smarty?
A: Be sure you set $compile_check=false once your templates are initially
   compiled. This will skip the unneeded step of testing if the template has
   changed since it was last compiled. If you have complex pages that don't
   change too often, turn on the caching engine and adjust your application so
   it doesn't do unnecessary work (like db calls) if a cached page is
   available. See the documentation for examples.
   
Q: Do you have a mailing list?
A:  We have a few mailing lists. "general" for you to share your ideas or ask
    questions, "dev" for those interested in the development efforts of Smarty,
    and "cvs" for those that would like to track the updates made in the cvs
    repository.

    send a blank e-mail message to:
      [email protected] (subscribe to the general list)
      [email protected] (unsubscribe from the general list)
      [email protected] (subscribe to digest)
      [email protected] (unsubscribe from digest)
      [email protected] (subscribe to the dev list)
      [email protected] (unsubscribe from the dev list)
      [email protected] (subscribe to the cvs list)
      [email protected] (unsubscribe from the cvs list)
    You can also browse the mailing list archives at
    http://marc.theaimsgroup.com/?l=smarty&r=1&w=2



Q: Can you change the mailing list so Reply-To sends to the list and not the
   user?
A: Yes we could, but no we won't. Use "Reply-All" in your e-mail client to send
   to the list. http://www.unicom.com/pw/reply-to-harmful.html

TROUBLESHOOTING
---------------

Q: Smarty doesn't work.
A: You must be using PHP 4.0.6 or later if you use any version of Smarty
   past 2.0.1. Read the BUGS file for more info.

Q: I get the following error when running Smarty:
   Warning:  Smarty error: problem creating directory "templates_c/239/239105369"
   in /path/to/Smarty.class.php on line 542
A: Your web server user does not have permission to write to the templates_c
   directory, or is unable to create the templates_c directory. Be sure the
   templates_c directory exists in the location defined in Smarty.class.php,
   and the web server user can write to it. If you do not know the web server
   user, chmod 777 the templates_c directory, reload the page, then check the
   file ownership of the files created in templates_c. Or, you can check the
   httpd.conf (usually in /usr/local/apache/conf) file for this setting:
   User nobody
   Group nobody

Q: I get the following error when running Smarty: Warning: Wrong parameter
   count for preg_replace() in Smarty.class.php on line 371
A: preg_replace had a parameter added in PHP 4.0.2 that Smarty
   requires. Upgrade to at least 4.0.6 to fix all known PHP issues with
   Smarty.

Q: I get this error when passing variables to {include}:
   Fatal error: Call to undefined function: get_defined_vars() in
   /path/to/Smarty/templates_c/index.tpl.php on line 8
A: get_defined_vars() was added to PHP 4.0.4. If you plan on passing
   variables to included templates, you will need PHP 4.0.6 or later.

Q: I get PHP errors in my {if} tag logic.
A: All conditional qualifiers must be separated by spaces. This syntax will not
   work: {if $name=="Wilma"} You must instead do this: {if $name == "Wilma"}.
   The reason for this is syntax ambiguity. Both "==" and "eq" are equivalent
   in the template parser, so something like {if $nameeq"Wilma"} wouldn't be
   parsable by the tokenizer.

Q: I'm changing my php code and/or templates, and my results are not getting
   updated.
A: This may be the result of your compile or cache settings. If you are
   changing your php code, your templates will not necessarily get recompiled
   to reflect the changes. Use $force_compile during develpment to avoid these
   situations. Also turn off caching during development when you aren't
   specifically testing it. You can also remove everything from your
   compile_dir and cache_dir and reload the page to be sure everything gets
   regenerated.

Q: I'm running Windows 2000 and I get blank content. My compiled PHP files are
   also zero length.
A: There seems to be a problem with some W2k machines and exclusive file
   locking. Comment out the flock() call in _write_file to get around this,
   although be aware this could possibly cause a problem with simultaneous
   writes to a file, especially with caching turned on. NOTE: As of Smarty
   1.4.0, a workaround was put in place that should solve this.

Q: The template goes into an infinite loop when I include included templates
   that pass local variables
A: This was fixed in 1.3.2 (new global attribute)

Q: Javascript is causing Smarty errors in my templates.
A: Surround your javascript with {literal}{/literal} tags. See the docs.

Q: I get "SAFE MODE Restriction in effect. ..."-errors when running smarty.
A: Use $smarty->use_sub_dirs = false when running php in safe mode.

MISC
----

Q: Can I use Macromedia's Dreamweaver to edit my templates?
A: Certainly. You might want to change your tag delimiters from {} to something
   that resembles valid HTML, like <!--{ }--> or <{ }> or something similar.
   This way the editor won't view the template tags as errors.

Q: Dreamweaver is urlencoding the template delimiters when they are in a SRC or
   HREF link. How do I get around this?
A: In Edit - Properties - Rewrite HTML you can specify if Dreamweaver should
   change special letters to %-equivalent or not. The default is on which
   produces this error.

HOWTO
-----
   
Q: How do I generate different cache files per template based on arguments
   passed to the page?
A: Use your $REQUEST_URI as the cache_id when fetching the page:

   global $REQUEST_URI; // if not already present
   $smarty->display('index.tpl',$REQUEST_URI);

   This will create a separate cache file for each unique URL when you call
   index.tpl. See the documentation for display() and fetch()

Q: How do I pass a template variable as a parameter? {function param={$varname}}
   does not work.
A: {function param=$varname} (You cannot nest template delimiters.)

Q: How do I include cached template(s) within a non-cached template?
A: One way to do it:

   $smarty->caching = true;
   $tpl1 = $smarty->fetch("internal1.tpl");
   $tpl2 = $smarty->fetch("internal2.tpl");
   $tpl3 = $smarty->fetch("internal3.tpl");

   $smarty->assign("tpl1_contents",$tpl1);
   $smarty->assign("tpl2_contents",$tpl2);
   $smarty->assign("tpl3_contents",$tpl3);

   $smarty->caching = false;
   $smarty->display('index.tpl');

   index.tpl
   ---------

   <table>
           <tr>
                   <td>{$tpl1_contents}</td>
                   <td>{$tpl2_contents}</td>
                   <td>{$tpl3_contents}</td>
           </tr>
   </table>




   Another approach:

   You could write a custom insert function to fetch your internal
   templates:

   <table>
           <tr>
                   <td>{insert name=fetch_tpl tpl="internal1.tpl"}</td>
                   <td>{insert name=fetch_tpl tpl="internal2.tpl"}</td>
                   <td>{insert name=fetch_tpl tpl="internal3.tpl"}</td>
           </tr>
   </table>