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| <HTML><HEAD><TITLE>phpBB Coding Standard Guidelines</TITLE> |
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| vLink=#0000ff><FONT face=verdana,arial,tahoma size=-1><A name=top></A> |
| <H2>phpBB Coding Standard Guidelines</H2>Comments or suggestions? email <A |
| href="mailto:nate@phpbb.com">nate@phpbb.com</A><BR><BR><A |
| href="#editor">Editor |
| Settings</A><BR><A |
| href="#naming">Naming |
| Conventions</A><BR><A |
| href="#layout">Code Layout</A><BR><A |
| href="#general">General |
| Guidelines</A><BR><BR><BR><A name=editor></A><A |
| href="#top">top</A> |
| <H3>Editor Settings</H3> |
| <P><B>Tabs vs Spaces:</B> In order to make this as simple as possible, we will |
| be using tabs, not spaces. Feel free to set how many spaces your editor uses |
| when it <B>displays</B> tabs, but make sure that when you <B>save</B> the file, |
| it's saving tabs and not spaces. This way, we can each have the code be |
| displayed the way we like it, without breaking the layout of the actual files. |
| </P> |
| <P><B>Linefeeds:</B> 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. If you |
| want advice on Windows text editors, just ask one of the developers. Some of |
| them do their editing on Win32. </P><BR><BR><A name=naming></A><A |
| href="#top">top</A> |
| <H3>Naming Conventions</H3> |
| <P>We will not be using any form of hungarian notation in our naming |
| conventions. Many of us believe that hungarian naming is one of the primary code |
| obfuscation techniques currently in use. </P> |
| <P><B>Variable Names:</B> Variable names should be in all lowercase, with words |
| separated by an underscore. <BR><BR> Example: <CODE><FONT |
| size=+1>$current_user</FONT></CODE> is right, but <CODE><FONT |
| size=+1>$currentuser</FONT></CODE> and <CODE><FONT |
| size=+1>$currentUser</FONT></CODE> are not. <BR><BR>Names should be descriptive, |
| but concise. We don't want huge sentences as our variable names, but typing an |
| extra couple of characters is always better than wondering what exactly a |
| certain variable is for. </P> |
| <P><B>Loop Indices:</B> The <I>only</I> situation where a one-character variable |
| name is allowed is when it's the index for some looping construct. In this case, |
| the index of the outer loop should always be $i. If there's a loop inside that |
| loop, its index should be $j, followed by $k, and so on. If the loop is being |
| indexed by some already-existing variable with a meaningful name, this guideline |
| does not apply. <BR><BR> Example: <PRE><FONT size=+1> |
| for ($i = 0; $i < $outer_size; $i++) |
| { |
| for ($j = 0; $j < $inner_size; $j++) |
| { |
| foo($i, $j); |
| } |
| } </FONT></PRE> |
| <P></P> |
| <P><B>Function Names:</B> Functions should also be named descriptively. We're |
| not programming in C here, we don't want to write functions called things like |
| "stristr()". Again, all lower-case names with words separated by a single |
| underscore character. Function names should preferably have a verb in them |
| somewhere. Good function names are <CODE><FONT |
| size=+1>print_login_status()</FONT></CODE>, <CODE><FONT |
| size=+1>get_user_data()</FONT></CODE>, etc.. </P> |
| <P><B>Function Arguments:</B> Arguments are subject to the same guidelines as |
| variable names. We don't want a bunch of functions like: <CODE><FONT |
| size=+1>do_stuff($a, $b, $c)</FONT></CODE>. In most cases, we'd like to be able |
| to tell how to use a function by just looking at its declaration. </P> |
| <P><B>Summary:</B> The basic philosophy here is to not hurt code clarity for the |
| sake of laziness. This has to be balanced by a little bit of common sense, |
| though; <CODE><FONT size=+1>print_login_status_for_a_given_user()</FONT></CODE> |
| goes too far, for example -- that function would be better named <CODE><FONT |
| size=+1>print_user_login_status()</FONT></CODE> , or just <CODE><FONT |
| size=+1>print_login_status()</FONT></CODE>. </P><BR><BR><A name=layout></A><A |
| href="#top">top</A> |
| <H3>Code Layout</H3> |
| <P><B>Standard header for new files:</B> Here a template of the header that must |
| be included at the start of all phpBB files: <PRE><FONT size=+1> |
| /*************************************************************************** |
| filename.php |
| ------------------- |
| begin : Sat June 17 2000 |
| copyright : (C) 2000 The phpBB Group |
| email : support@phpBB.com |
| |
| $Id: codingstandards.htm,v 1.3 2001/06/09 21:00:12 natec Exp $ |
| |
| ***************************************************************************/ |
| |
| /*************************************************************************** |
| * |
| * 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. |
| * |
| ***************************************************************************/ |
| </FONT></PRE> |
| <P></P> |
| <P><B>Always include the braces:</B> This is another case of being too lazy to |
| type 2 extra characters causing problems with code clarity. Even if the body of |
| some construct is only one line long, do <I>not</I> drop the braces. Just don't. |
| <BR><BR> Examples:<PRE><FONT size=+1> |
| /* These are all wrong. */ |
| if (condition) do_stuff(); |
| if (condition) |
| do_stuff(); |
| while (condition) |
| do_stuff(); |
| for ($i = 0; $i < size; $i++) |
| do_stuff($i); |
| |
| /* These are right. */ |
| if (condition) |
| { |
| do_stuff(); |
| } |
| while (condition) |
| { |
| do_stuff(); |
| } |
| for ($i = 0; $i < size; $i++) |
| { |
| do_stuff(); |
| } |
| </FONT></PRE> |
| <P></P> |
| <P><B>Where to put the braces:</B> This one is a bit of a holy war, but we're |
| going to use a style that can be summed up in one sentence: Braces always go on |
| their own line. The closing brace should also always be at the same column as |
| the corresponding opening brace. <BR><BR> Examples:<PRE><FONT size=+1> |
| if (condition) |
| { |
| while (condition2) |
| { |
| ... |
| } |
| } |
| else |
| { |
| ... |
| } |
| |
| for ($i = 0; $i < $size; $i++) |
| { |
| ... |
| } |
| |
| while (condition) |
| { |
| ... |
| } |
| |
| function do_stuff() |
| { |
| ... |
| } |
| </FONT></PRE> |
| <P></P> |
| <P><B>Use spaces between tokens:</B> This is another simple, easy step that |
| helps keep code readable without much effort. Whenever you write an assignment, |
| expression, etc.. Always leave <I>one</I> space between the tokens. Basically, |
| write code as if it was English. Put spaces between variable names and |
| operators. Don't put spaces just after an opening bracket or before a closing |
| bracket. Don't put spaces just before a comma or a semicolon. This is best shown |
| with a few examples. <BR><BR> Examples:<PRE><FONT size=+1> |
| /* Each pair shows the wrong way followed by the right way. */ |
| |
| $i=0; |
| $i = 0; |
| |
| if($i<7) ... |
| if ($i < 7) ... |
| |
| if ( ($i < 7)&&($j > 8) ) ... |
| if (($i < 7) && ($j > 8)) ... |
| |
| do_stuff( $i, "foo", $b ); |
| do_stuff($i, "foo", $b); |
| |
| for($i=0; $i<$size; $i++) ... |
| for($i = 0; $i < $size; $i++) ... |
| |
| $i=($j < $size)?0:1; |
| $i = ($j < $size) ? 0 : 1; |
| </FONT></PRE> |
| <P></P> |
| <P><B>Operator precedence:</B> 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. |
| <BR><BR> Examples:<PRE><FONT size=+1> |
| /* 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))) |
| </FONT></PRE> |
| <P></P> |
| <P><B>SQL code layout:</B> Since we'll all be using different editor settings, |
| don't try to do anything complex like aligning columns in SQL code. Do, however, |
| break statements onto their own lines. Here's a sample of how SQL code should |
| look. Note where the lines break, the capitalization, and the use of brackets. |
| <BR><BR> Examples:<PRE><FONT size=+1> |
| SELECT field1 AS something, field2, field3 |
| FROM table a, table b |
| WHERE (this = that) AND (this2 = that2) |
| </FONT></PRE> |
| <P></P> |
| <P><B>SQL insert statements:</B> SQL INSERT statements can be written in two |
| different ways. Either you specify explicitly the columns being inserted, or |
| you rely on knowing the order of the columns in the database and do not |
| specify them. We want to use the former approach, where it is explicitly |
| stated whcih columns are being inserted. This means our application-level code |
| will not depend on the order of the fields in the database, and will not be broken |
| if we add additional fields (unless they're specified as NOT NULL, of course). |
| <BR><BR> Examples:<PRE><FONT size=+1> |
| # This is not what we want. |
| INSERT INTO mytable |
| VALUES ('something', 1, 'else') |
| |
| # This is correct. |
| INSERT INTO mytable (column1, column2, column3) |
| VALUES ('something', 1, 'else') |
| </FONT></PRE> |
| <P></P><BR><BR><A name=general></A><A |
| href="#top">top</A> |
| <H3>General Guidelines</H3> |
| <P><B>Quoting strings:</B> There are two different ways to quote strings in PHP |
| - either with single quotes or with double quotes. The main difference is that |
| the parser does variable interpolation in double-quoted strings, but not in |
| single quoted strings. Because of this, you should <I>always</I> use single |
| quotes <I>unless</I> you specifically need variable interpolation to be done on |
| that string. This way, we can save the parser the trouble of parsing a bunch of |
| strings where no interpolation needs to be done. Also, if you are using a string |
| variable as part of a function call, you do not need to enclose that variable in |
| quotes. Again, this will just make unnecessary work for the parser. Note, |
| however, that nearly all of the escape sequences that exist for double-quoted |
| strings will not work with single-quoted strings. Be careful, and feel free to |
| break this guideline if it's making your code harder to read. |
| <BR><BR> Examples:<PRE><FONT size=+1> |
| /* wrong */ |
| $str = "This is a really long string with no variables for the parser to find."; |
| do_stuff("$str"); |
| |
| /* right */ |
| $str = 'This is a really long string with no variables for the parser to find.'; |
| do_stuff($str); |
| </FONT></PRE> |
| <P></P> |
| <P><B>Associative array keys:</B> 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. |
| <BR><BR> Examples:<PRE><FONT size=+1> |
| /* wrong */ |
| $foo = $assoc_array[blah]; |
| |
| /* right */ |
| $foo = $assoc_array['blah']; |
| </FONT></PRE> |
| <P></P> |
| <P><B>Comments:</B> Each function should be preceded by a comment that tells a |
| programmer everything they need to know to use that function. The meaning of |
| every parameter, the expected input, and the output are required as a minimal |
| comment. The function's behaviour in error conditions (and what those error |
| conditions are) should also be present. Nobody should have to look at the actual |
| source of a function in order to be able to call it with confidence in their own |
| code. <BR><BR>In addition, commenting any tricky, obscure, or otherwise |
| not-immediately-obvious code is clearly something we should be doing. Especially |
| important to document are any assumptions your code makes, or preconditions for |
| its proper operation. Any one of the developers should be able to look at any |
| part of the application and figure out what's going on in a reasonable amount of |
| time. </P> |
| <P><B>Magic numbers:</B> Don't use them. Use named constants for any literal |
| value other than obvious special cases. Basically, it's OK to check if an array |
| has 0 elements by using the literal 0. It's not OK to assign some special |
| meaning to a number and then use it everywhere as a literal. This hurts |
| readability AND maintainability. Included in this guideline is that we should be |
| using the constants TRUE and FALSE in place of the literals 1 and 0 -- even |
| though they have the same values, it's more obvious what the actual logic is |
| when you use the named constants. </P> |
| <P><B>Shortcut operators:</B> The only shortcut operators that cause readability |
| problems are the shortcut increment ($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. <BR><BR> Examples:<PRE><FONT size=+1> |
| /* wrong */ |
| $array[++$i] = $j; |
| $array[$i++] = $k; |
| |
| |
| /* right */ |
| $i++; |
| $array[$i] = $j; |
| |
| $array[$i] = $k; |
| $i++; |
| </FONT></PRE> |
| <P></P> |
| <P><B>Inline conditionals:</B> Inline conditionals should only be used to do |
| very simple things. Preferably, they will only be used to do assignments, and |
| not for function calls or anything complex at all. They can be harmful to |
| readability if used incorrectly, so don't fall in love with saving typing by |
| using them. <BR><BR> Examples:<PRE><FONT size=+1> |
| /* Bad place to use them */ |
| (($i < $size) && ($j > $size)) ? do_stuff($foo) : do_stuff($bar); |
| |
| |
| /* OK place to use them */ |
| $min = ($i < $j) ? $i : $j; |
| </FONT></PRE> |
| <P></P> |
| <P><B>Don't use uninitialized variables.</B> for phpBB 2, we intend to use a |
| higher level of run-time error reporting. This will mean that the use of an |
| uninitialized variable will be reported as an error. This will come up most |
| often when checking which HTML form variables were passed. These errors can be |
| avoided by using the built-in isset() function to check whether a variable has |
| been set. <BR><BR> Examples:<PRE><FONT size=+1> |
| /* Old way */ |
| if ($forum) ... |
| |
| |
| /* New way */ |
| if (isset($forum)) ... |
| </FONT></PRE> |
| <P></P><BR><BR><A href="#top">Return |
| to top</A> </FONT></BODY></HTML> |