Extending a PHP Class with Subclasses and instantiate all functions into one object -

i using smarty template engine (http://smarty.net) on website have additional, custom functions handle template compiling tasks.

in order able update smarty framework files (e.g. /smarty/smarty.class.php) , not having copy-paste custom function class inside smarty.class.php, thought "hey, let's make own class , extend smarty class!". however, can't work , appreciate enlightening advice :)

this got @ moment:

• web-root/
  • includes/
    • smarty.inc.php
  • smartylib/
    • smarty.class.php
    • smarty_compiler.class.php

smarty.class.php

the third party vendor file , class don't wanna touch:

class smarty {     // various vars declarations     public function __construct() {         // ...     }      function _compile_source($resource_name, &$source_content, &$compiled_content, $cache_include_path=null) {         // magic...         $smarty_compiler = new $this->compiler_class;         // more magic...     }      // more class methods declarations } 

smarty_compiler.class.php

another third party vendor file , class don't wanna touch:

class smarty_compiler extends smarty {     // various vars , methods declarations...      function _syntax_error($error_msg, $error_type = e_user_error, $file=null, $line=null) {         $this->_trigger_fatal_error("syntax error: $error_msg", $this->_current_file, $this->_current_line_no, $file, $line, $error_type);     }      // more various methods declarations... } 

smarty.inc.php

my custom smarty include file new subclasses , instantiating $smarty object:

/**  * extensions smarty class  */ class mysmarty extends smarty {     // different custom vars declarations      /**      * additional custom template compile function      */     public function compile ($template, &$errors) {         // custom code     } }  /**  * extensions smarty_compiler class  */ class mysmarty_compiler extends smarty {     // different custom vars declarations     var $_manual_compiler_errors = array();      /**      * replacement _syntax_error function      */     public function _syntax_error($error_msg, $error_type = e_user_error, $file=null, $line=null) {         global $_manual_compiler_errors;          if ($_manual_compiler_errors) {             array_push($_manual_compiler_errors, "smarty syntax error on line ".$this->_current_line_no.": $error_msg");         }else{             $this->_trigger_fatal_error("smarty syntax error: $error_msg", $this->_current_file, $this->_current_line_no, $file, $line, $error_type);         }     } }  // instantiate smarty include_once($_server['document_root'].'/smartylib/smarty.class.php'); $smarty = new smarty; $smarty->debugging = true; $smarty->force_compile = false; 

result , problem

okay hope intentions clear above code snippets: i want object $smarty contain also

1. my additional, new custom template function,
2. and replacement function

and because use "extends" 2 classes declaration, thought should work using:

$smarty->compile(...); $smarty->_syntax_error(...); 

but unfortunately doesn't :( add custom functions directly smarty class inside smarty.class.php - will, obviously, make file non-updateable.

what missing using 2 subclasses extending smarty class , while talking methods declared in them? or how approach extending third-party class custom/rewritten functions without touching original code?

thank you advice!

✅ based on this stackoverflow-question/answers able overcome problem , getting code run custom classes , methods.

solution (summarized)

class mysmarty extends smarty {     ... }  class mysmarty_compiler extends smarty {     function _syntax_error($error_msg, $error_type = e_user_error, $file=null, $line=null) {         ...     } }  // instantiate smarty new way include_once($_server['document_root'].'/smartylib/smarty.class.php'); $smarty = new mysmarty; // instantiate subclass, loads main class $smarty_compiler = new mysmarty_compiler; // overwrite $smarty_compiler object second patched subclass, loads smarty_compile class 

if still missed or recommendations, i'd happy hear :)