The purpose of this document is to lay out a clear set of guidelines for developing code for the Gallery project. The scope of this document is limited mainly to PHP code, although Gallery will occasionally use SQL and HTML.
Code conventions are important to programmers for a number of reasons:
This document has been largely created by culling information from the following documents:
Theme design/coding standards.
" Tabs to spaces set expandtab set smarttab " 2 Spaces in each case set tabstop=2 set shiftwidth=2 set softtabstop=2 " Maximum 100 characters in line set textwidth=99 " Set filetype set filetype=php
Add configration above to .vimrc file.
Make sure Your .vimrc file contain line
filetype plugin indent on
Then create file ~/.vim/ftplugin/g3.vim contain configuration as above. A the end append:
" Set filetype set filetype=php
After edit file in vim run command :set filetype=g3. After that appropriate config files will be load.
For indentation copy /usr/share/vim/*/indent/php.vim to ~/.vim/indent/ or add to configuration something like
" Set indentation set autoindent set smartindent
To configure Emacs to use Gallery's PHP style:
(load "php-style.el")
Any .php files you open in emacs should be in PHP mode, and it should follow Gallery 3's coding standards. Any .html.php files should be in SGML mode. To automatically indent, hit <tab> and it should do the right thing.
To configure Eclipse PDT to use Gallery's PHP style:
For debugging, it's useful to have a short template that gets expanded to the line used to add entries to Kohana's debug log. To do this:
Now every time while editing PHP files you enter klog and press Ctrl+Space, it will get expanded to the text entered in the pattern field above. The cursor will already be between the quotes and you can start typing the log message immediately. Make sure to press Enter after you finish writing in order for Eclipse to properly exit template editing mode.
Two spaces is the basic unit of indentation. Tabs are prohibited.
function my_function() {
// 2 spaces
code;
code;
if (indent_another_level) {
// Another 2 spaces
more_code;
more_code;
}
}
Avoid lines greater than 100 characters in all PHP files. You can break this exception in View files where we're generating HTML output if it would affect the display.
Here are some examples of breaking method calls:
some_method(long_expression1, long_expression2, long_expression3,
long_expression4, long_expression5);
var = some_method1(long_expression1,
some_method2(long_expression2, long_expression3));
Following are two examples of breaking an arithmetic expression. The first is preferred, since the break occurs outside the parenthesized expression, which is at a higher level.
// PREFER
long_name1 = long_name2 * (long_name3 + long_name4 - long_name5) +
4 * long_name6;
// AVOID
long_name1 = long_name2 * (long_name3 + long_name4
- long_name5) + 4 * longname6;
Following are two examples of indenting function declarations. The first is the conventional case where the arguments are indented under the open parenthesis. In the second case, the function name is so long that indenting under the parenthesis would require us to put many parameters on their own line which is not visually appealing. But we can't indent the follow on lines by 2 columns because then it would be hard to differentiate them from the code that follows, so we indent them 4 columns, as we do when indenting wrapping if-clauses (see below).
// CONVENTIONAL INDENTATION
function some_function($an_arg, $another_arg, $yet_another_arg,
$and_still_another) {
codeHere;
}
// INDENT 4 COLUMNS TO AVOID VERY DEEP INDENTS
function superExtraHorkingLongMethodName($an_arg, $an_arg, $an_arg,
$another_arg, $yet_another_arg, $yet_more_arg, $an_arg, $an_arg
$and_still_another) {
codeHere;
}
Line wrapping for if statements should generally align with the opening ( of the if ( statement. For example:
// This is fine
if ((condition1 && condition2) ||
(condition3 && condition4) ||
!(condition5 && condition6)) {
do_something_about_it();
}
// You can put the operators on the continuation line as well
if ((condition1 && condition2)
|| (condition3 && condition4)
|| !(condition5 && condition6)) {
do_something_about_it();
}
Expressions using the ternary operator should be parenthesized. Here are three acceptable ways to format ternary expressions:
$alpha = (a_long_boolean_expression) ? $beta : $gamma;
$alpha = (a_long_boolean_expression) ? $beta
: $gamma;
$alpha = (a_long_boolean_expression)
? $beta
: $gamma;
Ensure that your editor is saving files in the Unix format. This means lines are terminated with a newline, not with a CR/LF combo as they are on Win32, or whatever the Mac uses. Any decent Win32 editor should be able to do this, but it might not always be the default. Know your editor.
Same indention rules as for PHP files, except that you can break the 100 column line length if necessary to preserve proper output.
Naming conventions make programs more understandable by making them easier to read. They can also give information about the function of the identifier-for example, whether it's a constant, package, or class-which can be helpful in understanding the code.
In the block below, we'll refer to a capitalization strategy called under_score. In this strategy, multiple words are combined using an underscore between words, and none of the letters are capitalized. Acronyms should be all upper case.
There are two forms:
| Type | Description | Example |
| Files | File names are in lower_case with the exception of [[1][libraries]] which are required by Kohana to be Upper_Case. Try to keep your file names simple and descriptive.
Files containing only code (controllers, libraries, helpers, etc) should terminate in .php. Views should terminate in .html.php, so that editors can treat them as HTML files that contain PHP. |
album.php album_add.html.php |
| Classes | Class names are in Upper_Case and should be nouns. Try to keep your class names simple and descriptive. Acronyms should be upper case. The exception to this is helper classes containing only static functions. In this case, the class name is all in lower case. | class Album_Controller class ORM_MPTT |
| Variables | Variables are in lower_case.
Variable names should be short yet meaningful. The choice of a variable name should be mnemonic -- that is, designed to indicate to the casual observer the intent of its use. One-character variable names should be avoided except for temporary "throwaway" variables such as loop indexes. |
var $fields; var $user_information; |
| Functions | Functions are in lower_case and should be verbs. Functions that return boolean values should be in the form of a question as in is_enabled. The noun-verb formation makes code easier to read, eg "Is the user enabled?" becomes if ($user->is_enabled). | function some_function() |
| Constants | Constants should be all upper case. | define('MIN_WIDTH', 4); |
| Database Tables | Table names should use lower_case and nouns should be pluralized. | items user_roles |
| Database Fields | Field names should use lower_case. | last_name favorite_color |
When coding classes and functions, the following formatting rules should be followed:
The above rules are sometimes referred to as the K&R style. Example:
class Foo {
function get_bar($a, $b) {
// code
}
}
Each line should contain at most one statement. Example:
$argv++; // Correct $argc--; // Correct $argv++; $argc--; // AVOID!
Compound statements are statements that contain lists of statements enclosed in braces "{ statements }".
The enclosed statements should be indented one more level than the compound statement. The opening brace should be at the end of the line that begins the compound statement; the closing brace should begin a line and be indented to the beginning of the compound statement. Braces are used around all statements, even single statements, when they are part of a control structure, such as an if-else or for statement. This makes it easier to add statements without accidentally introducing bugs due to forgetting to add braces. Example:
if ($a) { // Correct
b();
c();
}
if ($a) { // Correct
b();
}
if ($a) // AVOID!
b();
if ($a) b(); // AVOID!
A return statement with a value should not use parentheses unless they make the return value more obvious in some way. Example:
return; return my_disk.size(); return (size ? size : defaultSize);
The if-else class of statements should have the following form:
if (condition) {
statements;
}
if (condition) {
statements;
} else {
statements;
}
if (condition) {
statements;
} else if (condition) {
statements;
} else {
statements;
}
Note:
if (condition) // AVOID! THIS OMITS THE BRACES {}!
statement;
The alternative if, elsif, else, endif syntax is used in templates (mixed HTML / PHP templates), but not in pure PHP files.
<div <? if (Foo::hasChanged()): ?> class="changed" <? elseif (Foo::isNew()): ?> class="new" <? else: ?> class="sameold" <? endif; ?> >
A for statement should have the following form:
for (initialization; condition; update) {
statements;
}
An empty for statement (one in which all the work is done in the initialization, condition, and update clauses) should have the following form:
for (initialization; condition; update);
When using the comma operator in the initialization or update clause of a for statement, avoid the complexity of using more than three variables. If needed, use separate statements before the for loop (for the initialization clause) or at the end of the loop (for the update clause).
A while statement should have the following form:
while (condition) {
statements;
}
An empty while statement should have the following form:
while (condition);
A do-while statement should have the following form:
do {
statements;
} while (condition);
A switch statement should have the following form:
switch (condition) {
case ABC:
statements;
// falls through
case DEF:
statements;
break;
case XYZ:
statements;
break;
default:
statements;
break;
}
Every time a case falls through (doesn't include a break statement), add a comment where the break statement would normally be. This is shown in the preceding code example with the // falls through comment. Every switch statement should include a default case. The break in the default case is redundant, but it prevents a fall-through error if later another case is added.
Blank lines improve readability by setting off sections of code that are logically related. Two blank lines should always be used in the following circumstances:
One blank line should always be used in the following circumstances:
Blank spaces should be used in the following circumstances: A keyword followed by a parenthesis should be separated by a space. Example:
while (true) {
...
}
Note that a blank space should not be used between a method name and its opening parenthesis. This helps to distinguish keywords from function calls. A blank space should appear after commas in argument lists. All binary operators except . should be separated from their operands by spaces. Blank spaces should never separate unary operators such as unary minus, increment ("++"), and decrement ("--") from their operands. Example:
$a += $c + $d;
$a = ($a + $b) / ($c * $d);
while ($n < $s) {
$n++;
}
print("size is $foo\n");
The expressions in a for statement should be separated by blank spaces. Example:
for (expr1; expr2; expr3)
Casts should not be followed by a blank space. Examples:
my_function((int)$a, (int)$b);
All code should be well commented. Good comments explain why a code is written in a particular way. You don't need to explain how it works -- that much we can figure out from reading the code. The reasoning behind your choices is the interesting part.
/* This is a good single line comment */
// This is a good single line comment
/*
* This is a good block comment. Note how the
* open and closing comment tokens are on their own lines.
*/
// This is a good block comment. All comments should be
// proper English sentences with proper punctuation.
/* Bad block comments should have the open and closing
* comment on their own line
*/
/* Worse. Block comments should have the open and closing
* comment on their own line */
Use of Perl/shell style comments (#) are not allowed. Multiple line C style comments should see the asterisks aligned in a column (including the first line).
In addition, commenting any tricky, obscure, or otherwise not-immediately-obvious code is clearly something we should be doing. Especially important to document are any assumptions your code makes, or preconditions for its proper operation. Any one of the developers should be able to look at any part of the application and figure out what's going on in a reasonable amount of time.
These should appear at the beginning of every file, and help to explain the purpose of the file, and its place in the Gallery hierarchy. For example, the Gallery's core module is named the GalleryCore package. Files in the classes directory are part of the Classes subpackage. When these comments apply to classes, they become the class comments. Such a comment might look like:
/**
* Short explanation (1 line!)
*
* Some more text which explains in more detail what
* the file does and who might be interested
* in understanding that.
*
* @version $Id: coding-standards.xml,v 1.6 2005/05/22 22:54:29 bharat Exp $
* @package GalleryCore
* @subpackage Classes
* @module GalleryModuleName
*/
These explain in detail what a function does, what parameters it expects and what is returned by the function. Function comments apply to classes as well, here they magically turn into method comments. Such a comment appears directly above a function definition looks like this:
/**
* Short explanation (1 line!)
*
* Some more text which explains in more detail what
* the function does and who might be interested
* in understanding that.
*
* @author Name <email address>
* @author Name2 <other email address>
* @param type description
* @return type description
* @throws IllegalArgumentException
*/
function functionName( ...
These are simple: They just quickly explain what a class varibale is used for, or what an included file does, or why we need it. These comments may be longer, if you have to explain more. They should appear just above the corresponding variable or include/require statement. They can be just one line and look like this:
/**
* Some explanation of the variable or file just below this comment.
*/
All files should contain the following text in a form where it will not interfere with the purpose of the file (i.e., commented out). In this example, it's presented in a commented out form for inclusion into PHP files.
<?php
/*
* Gallery - a web based photo album viewer and editor
* Copyright (C) 2000-2008 Bharat Mediratta
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
*/
?>
Occasionally you wind up checking in code that's not totally satisfactory. Sometimes this is inevitable. In order to locate these bits of code so that we find and resolve it later, use the following tags in a comment, above the code in question:
Keep in mind that you may not get back to this code for a while. You may not even be the one to fix the thing, so the more information that you provide while it's still fresh in your mind, the better. Potential solutions or workarounds are great, and may prove invaluable to whomever gets around to addressing the issue.
If the comment isn't clear it may be ignored and eventually deleted.
At some point in the future this will enable us to dictate the following:
Associative Array Keys In PHP, it's legal to use a literal string as a key to an associative array without quoting that string. We don't want to do this; the string should always be quoted to avoid confusion. Note that this is only when we're using a literal, not when we're using a variable. Examples:
$foo = $assoc_array[blah]; // WRONG $foo = $assoc_array["blah"]; // RIGHT
Using the Heredoc string format is not recommended. One reason why is because it breaks the indention model.
Anywhere you are unconditionally including a class file, use require_once(). Anywhere you are conditionally including a class file (for example, factory methods), use include_once(). Either of these will ensure that class files are included only once. They share the same file list, so you don't need to worry about mixing them. A file included with require_once() will not be included again by include_once().
Note: include_once() and require_once() are statements, not functions. You don't need parentheses around the filename to be included.
In PHP files, use <?php at the beginning of the file and omit the ?> at the end. Example:
<?php
class Some_Code {
function doSomething() {
return "Hello";
}
}
This looks weird, but it's important because it prevents a particular problem where you accidentally put extra characters after a closing ?>. Those characters then get printed out to the browser and interfere with the UI, or worse.
Template files (files mixing HTML and PHP named .html.php) should use short PHP open tags. Example:
<?= Some_Code::doSomething()?> <?= $variable ?> <? comment::ShowComments() ?>
Don't use uninitialized variables. Gallery uses a high level of run-time error reporting. This will mean that the use of an uninitialized variable will be reported as an error. This will come up most often when checking which HTML form variables were passed. These errors can be avoided by using the built-in isset() function to check whether a variable has been set. Examples:
// wrong if ($forum) ... if (!$forum) ... // correct if (isset($forum)) ... if (empty($forum)) ...
Don't use them. Use named constants for any literal value other than obvious special cases. Basically, it's OK to check if an array has 0 elements by using the literal 0. It's not OK to assign some special meaning to a number and then use it everywhere as a literal. This hurts readability and maintainability. Included in this guideline is that we should be using the constants true and false in place of the literals 1 and 0. Even though they have the same values, it's more obvious what the actual logic is when you use the named constants.
The only shortcut operators that cause readability problems are the shortcut increment ($i++) and decrement ($j--) operators. These operators should not be used as part of an expression. They can, however, be used on their own line. Using them in expressions is just not worth the headaches when debugging. Examples:
// WRONG $array[++$i] = $j; $array[$i++] = $k; // RIGHT $i++; $array[$i] = $j; $array[$i] = $k; $i++;
Do you know the exact precedence of all the operators in PHP? Neither do I. Don't guess. Always make it obvious by using brackets to force the precedence of an equation so you know what it does.
// what's the result? who knows. $bool = ($i < 7 && $j > 8 || $k == 4); // now you can be certain what I'm doing here. $bool = ($i < 7 && ($j < 8 || $k == 4))
Gallery 3 uses sentence-style capitalization rules. For sentence-style capitalization:
Reference: http://msdn.microsoft.com/en-us/library/aa511441.aspx#SentenceCaps
