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220672b - migrate syntax to rEST to allow html/docbook rendering
Lukas Smith authored
1 ========================
2 PHP Coding Standards
3 ========================
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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
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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.
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11
12 Code Implementation
13 -------------------
14
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15 0. Document your code in source files and the manual. [tm]
6d10159 comments & php_error_docref
Marcus Boerger authored
16
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17 1. Functions that are given pointers to resources should not free them
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18
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19 For instance, ``function int mail(char *to, char *from)`` should NOT free
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20 to and/or from.
21 Exceptions:
22
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23 - The function's designated behavior is freeing that resource. E.g. efree()
24
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
29 - Low-level parser routines, that are tightly integrated with the token
30 cache and the bison code for minimum memory copying overhead.
31
32 2. Functions that are tightly integrated with other functions within the
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33 same module, and rely on each other non-trivial behavior, should be
34 documented as such and declared 'static'. They should be avoided if
35 possible.
36
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37 3. Use definitions and macros whenever possible, so that constants have
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38 meaningful names and can be easily manipulated. The only exceptions
39 to this rule are 0 and 1, when used as false and true (respectively).
40 Any other use of a numeric constant to specify different behavior
41 or actions should be done through a #define.
42
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43 4. When writing functions that deal with strings, be sure to remember
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44 that PHP holds the length property of each string, and that it
45 shouldn't be calculated with strlen(). Write your functions in a such
46 a way so that they'll take advantage of the length property, both
47 for efficiency and in order for them to be binary-safe.
48 Functions that change strings and obtain their new lengths while
49 doing so, should return that new length, so it doesn't have to be
585e338 php4ize a bit.
Sterling Hughes authored
50 recalculated with strlen() (e.g. php_addslashes())
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51
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52 5. NEVER USE strncat(). If you're absolutely sure you know what you're doing,
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53 check its man page again, and only then, consider using it, and even then,
54 try avoiding it.
55
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56 6. Use ``PHP_*`` macros in the PHP source, and ``ZEND_*`` macros in the Zend
57 part of the source. Although the ``PHP_*`` macro's are mostly aliased to the
58 ``ZEND_*`` macros it gives a better understanding on what kind of macro
59 you're calling.
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60
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61 7. When commenting out code using a #if statement, do NOT use 0 only. Instead
f71490c Rasmus Lerdorf Multi-branch test commit to see if email notifications are working
rlerdorf authored
62 use "<svn username here>_0". For example, #if FOO_0, where FOO is your
63 svn user foo. This allows easier tracking of why code was commented out,
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64 especially in bundled libraries.
2e6d771 As per the suggestion on php-dev, now please #ifdef 0_<username here>
Dan Kalowsky authored
65
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66 8. Do not define functions that are not available. For instance, if a
67 library is missing a function, do not define the PHP version of the
68 function, and do not raise a run-time error about the function not
69 existing. End users should use function_exists() to test for the
70 existence of a function
ab0da7d It seems we're better to mention about missing functions.
Yasuo Ohgaki authored
71
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72 9. Prefer emalloc(), efree(), estrdup(), etc. to their standard C library
73 counterparts. These functions implement an internal "safety-net"
74 mechanism that ensures the deallocation of any unfreed memory at the
75 end of a request. They also provide useful allocation and overflow
76 information while running in debug mode.
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77
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78 In almost all cases, memory returned to the engine must be allocated
79 using emalloc().
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80
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81 The use of malloc() should be limited to cases where a third-party
82 library may need to control or free the memory, or when the memory in
83 question needs to survive between multiple requests.
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84
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85 Naming Conventions
86 ------------------
87
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88 1. Function names for user-level functions should be enclosed with in
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89 the PHP_FUNCTION() macro. They should be in lowercase, with words
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Ron Chmara authored
90 underscore delimited, with care taken to minimize the letter count.
5cc6344 Updated to reflect recent discussions on php-dev.
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91 Abbreviations should not be used when they greatly decrease the
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92 readability of the function name itself::
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93
94 Good:
95 'mcrypt_enc_self_test'
96 'mysql_list_fields'
97
98 Ok:
99 'mcrypt_module_get_algo_supported_key_sizes'
100 (could be 'mcrypt_mod_get_algo_sup_key_sizes'?)
101 'get_html_translation_table'
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102 (could be 'html_get_trans_table'?)
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103
104 Bad:
105 'hw_GetObjectByQueryCollObj'
106 'pg_setclientencoding'
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Ron Chmara authored
107 'jf_n_s_i'
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108
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109 2. If they are part of a "parent set" of functions, that parent should
5cc6344 Updated to reflect recent discussions on php-dev.
Ron Chmara authored
110 be included in the user function name, and should be clearly related
111 to the parent program or function family. This should be in the form
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112 of ``parent_*``::
113
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114 A family of 'foo' functions, for example:
115 Good:
116 'foo_select_bar'
117 'foo_insert_baz'
118 'foo_delete_baz'
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119
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120 Bad:
121 'fooselect_bar'
122 'fooinsertbaz'
123 'delete_foo_baz'
124
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125 3. Function names used by user functions should be prefixed
126 with ``_php_``, and followed by a word or an underscore-delimited list of
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127 words, in lowercase letters, that describes the function. If applicable,
128 they should be declared 'static'.
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129
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130 4. Variable names must be meaningful. One letter variable names must be
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131 avoided, except for places where the variable has no real meaning or
132 a trivial meaning (e.g. for (i=0; i<100; i++) ...).
133
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134 5. Variable names should be in lowercase. Use underscores to separate
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135 between words.
136
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137 6. Method names follow the 'studlyCaps' (also referred to as 'bumpy case'
2a8300e All technical reasons that prevented us from studlyCaps are solved
Marcus Boerger authored
138 or 'camel caps') naming convention, with care taken to minimize the
139 letter count. The initial letter of the name is lowercase, and each
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140 letter that starts a new 'word' is capitalized::
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141
142 Good:
143 'connect()'
144 'getData()'
145 'buildSomeWidget()'
146
147 Bad:
148 'get_Data()'
149 'buildsomewidget'
150 'getI()'
151
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152 7. Classes should be given descriptive names. Avoid using abbreviations where
153 possible. Each word in the class name should start with a capital letter,
154 without underscore delimiters (CampelCaps starting with a capital letter).
155 The class name should be prefixed with the name of the 'parent set' (e.g.
156 the name of the extension)::
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157
158 Good:
159 'Curl'
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160 'FooBar'
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161
162 Bad:
163 'foobar'
164 'foo_bar'
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Marcus Boerger authored
165
aceaabc Zeev Suraski PHP 4.0
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166 Syntax and indentation
167 ----------------------
168
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169 1. Never use C++ style comments (i.e. // comment). Always use C-style
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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
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178 2. Use K&R-style. Of course, we can't and don't want to
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179 force anybody to use a style he or she is not used to, but,
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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
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Egon Schmid authored
183 indentation and comment styles and up to function declaration
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184 syntax. Also see Indentstyle_.
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185
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186 .. _Indentstyle: http://www.catb.org/~esr/jargon/html/I/indent-style.html
7d220af small clarification
Hartmut Holzgraefe authored
187
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188 3. Be generous with whitespace and braces. Keep one empty line between the
189 variable declaration section and the statements in a block, as well as
190 between logical statement groups in a block. Maintain at least one empty
191 line between two functions, preferably two. Always prefer::
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192
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193 if (foo) {
194 bar;
195 }
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196
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197 to:
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198
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199 if(foo)bar;
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200
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201 4. When indenting, use the tab character. A tab is expected to represent
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jparise authored
202 four spaces. It is important to maintain consistency in indenture so
203 that definitions, comments, and control structures line up correctly.
204
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205 5. Preprocessor statements (#if and such) MUST start at column one. To
bfed043 Include Sascha's indendation hint
Marcus Boerger authored
206 indent preprocessor directives you should put the # at the beginning
207 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
208
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209 Testing
210 -------
211
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212 1. Extensions should be well tested using *.phpt tests. Read about that
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213 in README.TESTING.
214
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215 Documentation and Folding Hooks
216 -------------------------------
217
218 In order to make sure that the online documentation stays in line with
219 the code, each user-level function should have its user-level function
220 prototype before it along with a brief one-line description of what the
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221 function does. It would look like this::
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222
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223 /* {{{ proto int abs(int number)
224 Returns the absolute value of the number */
225 PHP_FUNCTION(abs)
226 {
227 ...
228 }
229 /* }}} */
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230
231 The {{{ symbols are the default folding symbols for the folding mode in
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232 Emacs and vim (set fdm=marker). Folding is very useful when dealing with
233 large files because you can scroll through the file quickly and just unfold
234 the function you wish to work on. The }}} at the end of each function marks
25c3a3a Rasmus Lerdorf vim-6 does folding - clean up a bunch of missing folding tags plus
rlerdorf authored
235 the end of the fold, and should be on a separate line.
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236
237 The "proto" keyword there is just a helper for the doc/genfuncsummary script
238 which generates a full function summary. Having this keyword in front of the
239 function prototypes allows us to put folds elsewhere in the code without
240 messing up the function summary.
241
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242 Optional arguments are written like this::
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243
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244 /* {{{ proto object imap_header(int stream_id, int msg_no [, int from_length [, int subject_length [, string default_host]]])
245 Returns a header object with the defined parameters */
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246
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247 And yes, please keep the prototype on a single line, even if that line
248 is massive.
249
250 New and Experimental Functions
251 -----------------------------------
252 To reduce the problems normally associated with the first public
253 implementation of a new set of functions, it has been suggested
254 that the first implementation include a file labeled 'EXPERIMENTAL'
255 in the function directory, and that the functions follow the
256 standard prefixing conventions during their initial implementation.
257
258 The file labelled 'EXPERIMENTAL' should include the following
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259 information::
260
261 Any authoring information (known bugs, future directions of the module).
9421ad5 Rasmus Lerdorf cvs->svn
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262 Ongoing status notes which may not be appropriate for SVN comments.
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263
d47e483 As per andi, similar names are for legacy reasons only.
Ron Chmara authored
264 Aliases & Legacy Documentation
265 -----------------------------------
266 You may also have some deprecated aliases with close to duplicate
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Ron Chmara authored
267 names, for example, somedb_select_result and somedb_selectresult. For
8a5402c Fixed some spelling errors.
Egon Schmid authored
268 documentation purposes, these will only be documented by the most
d47e483 As per andi, similar names are for legacy reasons only.
Ron Chmara authored
269 current name, with the aliases listed in the documentation for
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Ron Chmara authored
270 the parent function. For ease of reference, user-functions with
271 completely different names, that alias to the same function (such as
272 highlight_file and show_source), will be separately documented. The
273 proto should still be included, describing which function is aliased.
274
d47e483 As per andi, similar names are for legacy reasons only.
Ron Chmara authored
275 Backwards compatible functions and names should be maintained as long
276 as the code can be reasonably be kept as part of the codebase. See
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Egon Schmid authored
277 /phpdoc/README for more information on documentation.
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