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Coding Standard

Consistency is important, even more so when writing open-source code, since the code belongs to millions on eyeballs, and bug-fixing relies on this teeming millions to actually locate bugs and understand how to solve it.

This is when, when writing anything for PrestaShop, be it a theme, a module or a core patch, you should strive to follow the following guidelines. They are the ones that the PrestaShop developers adhere to, and following theme is the surest way to have you code be elegantly integrated in PrestaShop.

In short, having code consistency helps keeping the code readable and maintainable.

If use an IDE, you can use the CodeSniffer code validator to help you write better code.

Summary

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$my_var = 17;
$a = $b;

Operators

1. "+", "-", "*", "/", "=" and any combination of them (e.g. "/=") need a space between their left and right members.

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   $a + 17; $result = $b / 2; $i += 34;

2. "." does not have a space between its left and right members.

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   echo $a.$b; $c = $d.$this->foo();

   Note
   title Recommendation
   For performance reasons, please do not overuse concatenation.

3. ".=" needs a space between its left and right members.

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   $a .= 'Debug';

4. When testing a boolean variable, do not use a comparison operator, but directly use the value itself, or the value prefixed with an exclamation mark:

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   // do not use this if ($var == true) // ...nor this if ($var == false) // use this if ($var) // ...or this if (!$var)

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1. if, elseif, while, for: need a space between the if keyword and the parentheses ().

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   if (<condition>) ... while (<condition>)

2. When a combination of if and else is used and both can return a value, the else has to be omitted.

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   if (<condition>) return false; return true;

   Note
   title Recommendation
   We recommend one return per method/function.

3. When a method/function returns a boolean and the current method/function's returned value depends on it, the if statement has to be avoided.

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   public aFirstMethod() { return $this->aSecondMethod(); }

4. Tests must be grouped by entity.

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   if ($price AND !empty($price)) ... if (!Validate::$myObject OR $myObject->id === NULL) ...

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1. Inside functions and methods, only the "//" comment tag is allowed.

2. After the "//" comment marker, a space is required: // Comment.

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   // My great comment

3. The "//" comment marker is tolerated at the end of a code line.

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   $a = 17 + 23; // A comment inside my example function

4. Outside of functions and methods, only the "/" and "/" comment markers are allowed.

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   /* This method is required for compatibility issues */ public function foo() { // Some code explanation right here ... }

5. PHP Doc comment block is required before the declaration of the method.

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   /** * Return field value if possible (both classical and multilingual fields) * * Case 1: Return value if present in $_POST / $_GET * Case 2: Return object value * * @param object $obj Object * @param string $key Field name * @param integer $id_lang Language id (optional) * @return string */ protected function getFieldValue($obj, $key, $id_lang = NULL)

   Info
   title For more informations
   For more information about the PHP Doc syntax: http://manual.phpdoc.org/HTMLSmartyConverter/HandS/phpDocumentor/tutorial_tags.pkg.html.

Return values

1. The return statement does not need brackets, except when it deals with a composed expression.

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   return $result; return ($a + $b); return (a() - b()); return true;

2. The return statement can be used to break out of a function.

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   return;

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1. Keywords must be written in uppercase.

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   SELECT `firstname` FROM `'._DB_PREFIX_.'customer`

2. Back quotes ("`") must be used around SQL field names and table names.

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   SELECT p.`foo`, c.`bar` FROM `'._DB_PREFIX_.'product` p, `'._DB_PREFIX_.'customer` c

3. Table aliases have to be named by taking the first letter of each word, and must be lowercase.

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   SELECT p.`id_product`, pl.`name` FROM `'._DB_PREFIX_.'product` p NATURAL JOIN `'._DB_PREFIX_.'product_lang` pl

4. When conflicts between table aliases occur, the second character has to be also used in the name.

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   SELECT ca.`id_product`, cu.`firstname` FROM `'._DB_PREFIX_.'cart` ca, `'._DB_PREFIX_.'customer` cu

5. Indentation has to be done for each clause.

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   $query = 'SELECT pl.`name` FROM `'._DB_PREFIX_.'product_lang` pl WHERE pl.`id_product` = 17';

6. It is forbidden to make a JOIN in a WHERE clause.

Installing the code validator

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