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aceaabc @zsuraski PHP 4.0
zsuraski authored
1 PHP Coding Standards
2 ====================
3
4
5 This file lists several standards that any programmer, adding or changing
6 code in PHP, should follow. Since this file was added at a very late
7 stage of the development of PHP v3.0, the code base does not (yet) fully
45807e6 @jparise Added a brief section documenting the preference of tabs over spaces.
jparise authored
8 follow it, but it's going in that general direction. Since we are now
9 well into the version 4 releases, many sections have been recoded to use
10 these rules.
aceaabc @zsuraski PHP 4.0
zsuraski authored
11
12
13 Code Implementation
14 -------------------
15
6d10159 comments & php_error_docref
Marcus Boerger authored
16 [0] Document your code in source files and the manual. [tm]
17
aceaabc @zsuraski PHP 4.0
zsuraski authored
18 [1] Functions that are given pointers to resources should not free them
19
20 For instance, function int mail(char *to, char *from) should NOT free
21 to and/or from.
22 Exceptions:
23
24 - The function's designated behavior is freeing that resource. E.g. efree()
25 - The function is given a boolean argument, that controls whether or not
26 the function may free its arguments (if true - the function must free its
27 arguments, if false - it must not)
28 - Low-level parser routines, that are tightly integrated with the token
29 cache and the bison code for minimum memory copying overhead.
30
31 [2] Functions that are tightly integrated with other functions within the
32 same module, and rely on each other non-trivial behavior, should be
33 documented as such and declared 'static'. They should be avoided if
34 possible.
35
36 [3] Use definitions and macros whenever possible, so that constants have
37 meaningful names and can be easily manipulated. The only exceptions
38 to this rule are 0 and 1, when used as false and true (respectively).
39 Any other use of a numeric constant to specify different behavior
40 or actions should be done through a #define.
41
42 [4] When writing functions that deal with strings, be sure to remember
43 that PHP holds the length property of each string, and that it
44 shouldn't be calculated with strlen(). Write your functions in a such
45 a way so that they'll take advantage of the length property, both
46 for efficiency and in order for them to be binary-safe.
47 Functions that change strings and obtain their new lengths while
48 doing so, should return that new length, so it doesn't have to be
585e338 php4ize a bit.
Sterling Hughes authored
49 recalculated with strlen() (e.g. php_addslashes())
aceaabc @zsuraski PHP 4.0
zsuraski authored
50
a072914 both these entries are bad, and were never agreed upon.
Sterling Hughes authored
51 [5] NEVER USE strncat(). If you're absolutely sure you know what you're doing,
aceaabc @zsuraski PHP 4.0
zsuraski authored
52 check its man page again, and only then, consider using it, and even then,
53 try avoiding it.
54
a072914 both these entries are bad, and were never agreed upon.
Sterling Hughes authored
55 [6] Use PHP_* macros in the PHP source, and ZEND_* macros in the Zend
612d5b9 - spaces instead of tabs
Derick Rethans authored
56 part of the source. Although the PHP_* macro's are mostly aliased to the
57 ZEND_* macros it gives a better understanding on what kind of macro you're
58 calling.
aceaabc @zsuraski PHP 4.0
zsuraski authored
59
a072914 both these entries are bad, and were never agreed upon.
Sterling Hughes authored
60 [7] When commenting out code using a #if statement, do NOT use 0 only. Instead
6c13299 rewrite paragraph 9
Marcus Boerger authored
61 use "<cvs username here>_0". For example, #if FOO_0, where FOO is your
2e6d771 As per the suggestion on php-dev, now please #ifdef 0_<username here>
Dan Kalowsky authored
62 cvs user foo. This allows easier tracking of why code was commented out,
63 especially in bundled libraries.
64
a072914 both these entries are bad, and were never agreed upon.
Sterling Hughes authored
65 [8] Do not define functions that are not available. For instance, if a
d6b4462 @jparise Reword item 10 for greater clarity.
jparise authored
66 library is missing a function, do not define the PHP version of the
67 function, and do not raise a run-time error about the function not
68 existing. End users should use function_exists() to test for the
69 existence of a function
ab0da7d It seems we're better to mention about missing functions.
Yasuo Ohgaki authored
70
a072914 both these entries are bad, and were never agreed upon.
Sterling Hughes authored
71 [9] Prefer emalloc(), efree(), estrdup(), etc. to their standard C library
e79772d @jparise Adding a new item (number 11) that explains why it's important to use
jparise authored
72 counterparts. These functions implement an internal "safety-net"
73 mechanism that ensures the deallocation of any unfreed memory at the
74 end of a request. They also provide useful allocation and overflow
75 information while running in debug mode.
76
77 In almost all cases, memory returned to the engine must be allocated
78 using emalloc().
79
80 The use of malloc() should be limited to cases where a third-party
81 library may need to control or free the memory, or when the memory in
82 question needs to survive between multiple requests.
83
aceaabc @zsuraski PHP 4.0
zsuraski authored
84 Naming Conventions
85 ------------------
86
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
87 [1] Function names for user-level functions should be enclosed with in
8e7147a - Use PHP_ instead of ZEND_
Derick Rethans authored
88 the PHP_FUNCTION() macro. They should be in lowercase, with words
aa20347 Updated naming standards as per 9/12 dev/doc discussion.
Ron Chmara authored
89 underscore delimited, with care taken to minimize the letter count.
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
90 Abbreviations should not be used when they greatly decrease the
91 readability of the function name itself.
aa20347 Updated naming standards as per 9/12 dev/doc discussion.
Ron Chmara authored
92
93 Good:
94 'mcrypt_enc_self_test'
95 'mysql_list_fields'
96
97 Ok:
98 'mcrypt_module_get_algo_supported_key_sizes'
99 (could be 'mcrypt_mod_get_algo_sup_key_sizes'?)
100 'get_html_translation_table'
101 (could be 'html_get_trans_table'?)
102
103 Bad:
104 'hw_GetObjectByQueryCollObj'
105 'pg_setclientencoding'
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
106 'jf_n_s_i'
b94bd05 - Update codinf standards with the posted RFC (results from PEAR Meeting...
Derick Rethans authored
107
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
108 [2] If they are part of a "parent set" of functions, that parent should
109 be included in the user function name, and should be clearly related
110 to the parent program or function family. This should be in the form
111 of parent_*.
112
113 A family of 'foo' functions, for example:
114 Good:
115 'foo_select_bar'
116 'foo_insert_baz'
117 'foo_delete_baz'
aceaabc @zsuraski PHP 4.0
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118
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
119 Bad:
120 'fooselect_bar'
121 'fooinsertbaz'
122 'delete_foo_baz'
123
124 [3] Function names used by user functions should be prefixed
585e338 php4ize a bit.
Sterling Hughes authored
125 with "_php_", and followed by a word or an underscore-delimited list of
aceaabc @zsuraski PHP 4.0
zsuraski authored
126 words, in lowercase letters, that describes the function. If applicable,
127 they should be declared 'static'.
b94bd05 - Update codinf standards with the posted RFC (results from PEAR Meeting...
Derick Rethans authored
128
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
129 [4] Variable names must be meaningful. One letter variable names must be
aceaabc @zsuraski PHP 4.0
zsuraski authored
130 avoided, except for places where the variable has no real meaning or
131 a trivial meaning (e.g. for (i=0; i<100; i++) ...).
132
8a5402c Fixed some spelling errors.
Egon Schmid authored
133 [5] Variable names should be in lowercase. Use underscores to separate
aceaabc @zsuraski PHP 4.0
zsuraski authored
134 between words.
135
2a8300e All technical reasons that prevented us from studlyCaps are solved
Marcus Boerger authored
136 [6] Method names follow the 'studlyCaps' (also referred to as 'bumpy case'
137 or 'camel caps') naming convention, with care taken to minimize the
138 letter count. The initial letter of the name is lowercase, and each
139 letter that starts a new 'word' is capitalized.
140
141 Good:
142 'connect()'
143 'getData()'
144 'buildSomeWidget()'
145
146 Bad:
147 'get_Data()'
148 'buildsomewidget'
149 'getI()'
150
151 [7] Classes should be given descriptive names. Avoid using abbreviations
b94bd05 - Update codinf standards with the posted RFC (results from PEAR Meeting...
Derick Rethans authored
152 where possible. Each word in the class name should start with a capital
153 letter, with words underscore delimited. The class name should be prefixed
154 with the name of the 'parent set'.
155
156 Good:
157 'Curl'
158 'Foo_Bar'
159
160 Bad:
161 'foobar'
162 'foo_bar'
163 'FooBar'
164
aceaabc @zsuraski PHP 4.0
zsuraski authored
165
166 Syntax and indentation
167 ----------------------
168
169 [1] Never use C++ style comments (i.e. // comment). Always use C-style
170 comments instead. PHP is written in C, and is aimed at compiling
171 under any ANSI-C compliant compiler. Even though many compilers
172 accept C++-style comments in C code, you have to ensure that your
173 code would compile with other compilers as well.
174 The only exception to this rule is code that is Win32-specific,
175 because the Win32 port is MS-Visual C++ specific, and this compiler
176 is known to accept C++-style comments in C code.
177
178 [2] Use K&R-style. Of course, we can't and don't want to
45807e6 @jparise Added a brief section documenting the preference of tabs over spaces.
jparise authored
179 force anybody to use a style he or she is not used to, but,
aceaabc @zsuraski PHP 4.0
zsuraski authored
180 at the very least, when you write code that goes into the core
181 of PHP or one of its standard modules, please maintain the K&R
182 style. This applies to just about everything, starting with
8a5402c Fixed some spelling errors.
Egon Schmid authored
183 indentation and comment styles and up to function declaration
aceaabc @zsuraski PHP 4.0
zsuraski authored
184 syntax.
7d220af small clarification
Hartmut Holzgraefe authored
185
29fa203 Update URL.
Sebastian Bergmann authored
186 (see also http://www.catb.org/~esr/jargon/html/I/indent-style.html)
aceaabc @zsuraski PHP 4.0
zsuraski authored
187
45807e6 @jparise Added a brief section documenting the preference of tabs over spaces.
jparise authored
188 [3] Be generous with whitespace and braces. Always prefer:
189
612d5b9 - spaces instead of tabs
Derick Rethans authored
190 if (foo) {
191 bar;
192 }
45807e6 @jparise Added a brief section documenting the preference of tabs over spaces.
jparise authored
193
612d5b9 - spaces instead of tabs
Derick Rethans authored
194 to:
45807e6 @jparise Added a brief section documenting the preference of tabs over spaces.
jparise authored
195
612d5b9 - spaces instead of tabs
Derick Rethans authored
196 if(foo)bar;
45807e6 @jparise Added a brief section documenting the preference of tabs over spaces.
jparise authored
197
8a5402c Fixed some spelling errors.
Egon Schmid authored
198 Keep one empty line between the variable declaration section and
aceaabc @zsuraski PHP 4.0
zsuraski authored
199 the statements in a block, as well as between logical statement
200 groups in a block. Maintain at least one empty line between
201 two functions, preferably two.
202
45807e6 @jparise Added a brief section documenting the preference of tabs over spaces.
jparise authored
203 [4] When indenting, use the tab character. A tab is expected to represent
204 four spaces. It is important to maintain consistency in indenture so
205 that definitions, comments, and control structures line up correctly.
206
356e8f9 @wez word fix
wez authored
207 [5] Preprocessor statements (#if and such) MUST start at column one. To
bfed043 Include Sascha's indendation hint
Marcus Boerger authored
208 indent preprocessor directives you should put the # at the beginning
209 of a line, followed by any number of whitespace.
9a33556 Newer compilers don't need this so many people don't know. Hence we make
Marcus Boerger authored
210
aceaabc @zsuraski PHP 4.0
zsuraski authored
211 Documentation and Folding Hooks
212 -------------------------------
213
214 In order to make sure that the online documentation stays in line with
215 the code, each user-level function should have its user-level function
216 prototype before it along with a brief one-line description of what the
217 function does. It would look like this:
218
219 /* {{{ proto int abs(int number)
8a5402c Fixed some spelling errors.
Egon Schmid authored
220 Returns the absolute value of the number */
8e7147a - Use PHP_ instead of ZEND_
Derick Rethans authored
221 PHP_FUNCTION(abs)
585e338 php4ize a bit.
Sterling Hughes authored
222 {
aceaabc @zsuraski PHP 4.0
zsuraski authored
223 ...
224 }
225 /* }}} */
226
227 The {{{ symbols are the default folding symbols for the folding mode in
25c3a3a @rlerdorf vim-6 does folding - clean up a bunch of missing folding tags plus
rlerdorf authored
228 Emacs and vim (set fdm=marker). Folding is very useful when dealing with
229 large files because you can scroll through the file quickly and just unfold
230 the function you wish to work on. The }}} at the end of each function marks
231 the end of the fold, and should be on a separate line.
aceaabc @zsuraski PHP 4.0
zsuraski authored
232
233 The "proto" keyword there is just a helper for the doc/genfuncsummary script
234 which generates a full function summary. Having this keyword in front of the
235 function prototypes allows us to put folds elsewhere in the code without
236 messing up the function summary.
237
238 Optional arguments are written like this:
239
240 /* {{{ proto object imap_header(int stream_id, int msg_no [, int from_length [, int subject_length [, string default_host]]])
8a5402c Fixed some spelling errors.
Egon Schmid authored
241 Returns a header object with the defined parameters */
aceaabc @zsuraski PHP 4.0
zsuraski authored
242
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
243 And yes, please keep the prototype on a single line, even if that line
244 is massive.
245
246 New and Experimental Functions
247 -----------------------------------
248 To reduce the problems normally associated with the first public
249 implementation of a new set of functions, it has been suggested
250 that the first implementation include a file labeled 'EXPERIMENTAL'
251 in the function directory, and that the functions follow the
252 standard prefixing conventions during their initial implementation.
253
254 The file labelled 'EXPERIMENTAL' should include the following
255 information:
8a5402c Fixed some spelling errors.
Egon Schmid authored
256 Any authoring information (known bugs, future directions of the module).
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
257 Ongoing status notes which may not be appropriate for CVS comments.
aceaabc @zsuraski PHP 4.0
zsuraski authored
258
d47e483 As per andi, similar names are for legacy reasons only.
Ron Chmara authored
259 Aliases & Legacy Documentation
260 -----------------------------------
261 You may also have some deprecated aliases with close to duplicate
aa20347 Updated naming standards as per 9/12 dev/doc discussion.
Ron Chmara authored
262 names, for example, somedb_select_result and somedb_selectresult. For
8a5402c Fixed some spelling errors.
Egon Schmid authored
263 documentation purposes, these will only be documented by the most
d47e483 As per andi, similar names are for legacy reasons only.
Ron Chmara authored
264 current name, with the aliases listed in the documentation for
aa20347 Updated naming standards as per 9/12 dev/doc discussion.
Ron Chmara authored
265 the parent function. For ease of reference, user-functions with
266 completely different names, that alias to the same function (such as
267 highlight_file and show_source), will be separately documented. The
268 proto should still be included, describing which function is aliased.
269
d47e483 As per andi, similar names are for legacy reasons only.
Ron Chmara authored
270 Backwards compatible functions and names should be maintained as long
271 as the code can be reasonably be kept as part of the codebase. See
8a5402c Fixed some spelling errors.
Egon Schmid authored
272 /phpdoc/README for more information on documentation.
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