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<td><h1>CodeIgniter User Guide Version 1.7.1</h1></td>
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<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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<a href="http://codeigniter.com/">CodeIgniter Home</a> &nbsp;&#8250;&nbsp;
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<a href="../index.html">User Guide Home</a> &nbsp;&#8250;&nbsp;
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Style Guide
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<!-- START CONTENT -->
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<div id="content">
63 
 
64 
 
65 
<h1>General Style and Syntax</h1>
66 
 
67 
<p>The following page describes the coding rules use adhere to when developing CodeIgniter.</p>
68 
 
69 
 
70 
<h2>Table of Contents</h2>
71 
<ul class="minitoc">
72 
	<li><a href="#file_format">File Format</a></li>
73 
	<li><a href="#php_closing_tag">PHP Closing Tag</a></li>
74 
	<li><a href="#class_and_method_naming">Class and Method Naming</a></li>
75 
	<li><a href="#variable_names">Variable Names</a></li>
76 
	<li><a href="#commenting">Commenting</a></li>
77 
	<li><a href="#constants">Constants</a></li>
78 
	<li><a href="#true_false_and_null">TRUE, FALSE, and NULL</a></li>
79 
	<li><a href="#logical_operators">Logical Operators</a></li>
80 
	<li><a href="#comparing_return_values_and_typecasting">Comparing Return Values and Typecasting</a></li>
81 
	<li><a href="#debugging_code">Debugging Code</a></li>
82 
	<li><a href="#whitespace_in_files">Whitespace in Files</a></li>
83 
	<li><a href="#compatibility">Compatibility</a></li>
84 
	<li><a href="#class_and_file_names_using_common_words">Class and File Names using Common Words</a></li>
85 
	<li><a href="#database_table_names">Database Table Names</a></li>
86 
	<li><a href="#one_file_per_class">One File per Class</a></li>
87 
	<li><a href="#whitespace">Whitespace</a></li>
88 
	<li><a href="#line_breaks">Line Breaks</a></li>
89 
	<li><a href="#code_indenting">Code Indenting</a></li>
90 
	<li><a href="#bracket_spacing">Bracket and Parenthetic Spacing</li>
91 
	<li><a href="#localized_text_in_control_panel">Localized Text in Control Panel</a></li>
92 
	<li><a href="#private_methods_and_variables">Private Methods and Variables</a></li>
93 
	<li><a href="#php_errors">PHP Errors</a></li>
94 
	<li><a href="#short_open_tags">Short Open Tags</a></li>
95 
	<li><a href="#one_statement_per_line">One Statement Per Line</a></li>
96 
	<li><a href="#strings">Strings</a></li>
97 
	<li><a href="#sql_queries">SQL Queries</a></li>
98 
	<li><a href="#default_function_arguments">Default Function Arguments</a></li>
99 
	<li><a href="#overlapping_tag_parameters">Overlapping Tag Parameters</a></li>
100 
</ul>
101 
 
102 
<li>
103 
 
104 
		<h2><a name="file_format"></a>File Format</h2>
105 
		<div class="guidelineDetails">
106 
			<p>Files should be saved with Unicode (UTF-8) encoding.  The <abbr title="Byte Order Mark">BOM</abbr>
107 
				should <em>not</em> be used.  Unlike UTF-16 and UTF-32, there's no byte order to indicate in
108 
				a UTF-8 encoded file, and the <abbr title="Byte Order Mark">BOM</abbr> can have a negative side effect in PHP of sending output,
109 
				preventing the application from being able to set its own headers.  Unix line endings should
110 
				be used (LF).</p>
111 
 
112 
			<p>Here is how to apply these settings in some of the more common text editors.  Instructions for your
113 
				text editor may vary; check your text editor's documentation.</p>
114 
 
115 
			<h5>TextMate</h5>
116 
 
117 
			<ol>
118 
				<li>Open the Application Preferences</li>
119 
				<li>Click Advanced, and then the "Saving" tab</li>
120 
				<li>In "File Encoding", select "UTF-8 (recommended)"</li>
121 
				<li>In "Line Endings", select "LF (recommended)"</li>
122 
				<li><em>Optional:</em> Check "Use for existing files as well" if you wish to modify the line
123 
					endings of files you open to your new preference.</li>
124 
			</ol>
125 
 
126 
			<h5>BBEdit</h5>
127 
 
128 
			<ol>
129 
				<li>Open the Application Preferences</li>
130 
				<li>Select "Text Encodings" on the left.</li>
131 
				<li>In "Default text encoding for new documents", select "Unicode (UTF-8, no BOM)"</li>
132 
				<li><em>Optional:</em> In "If file's encoding can't be guessed, use", select
133 
					"Unicode (UTF-8, no BOM)"</li>
134 
				<li>Select "Text Files" on the left.</li>
135 
				<li>In "Default line breaks", select "Mac OS X and Unix (LF)"</li>
136 
			</ol>
137 
		</div>
138 
 
139 
		<h2><a name="php_closing_tag"></a>PHP Closing Tag</h2>
140 
		<div class="guidelineDetails">
141 
			<p>The PHP closing tag on a PHP document <strong>?&gt;</strong> is optional to the PHP parser.  However, if used, any whitespace following the closing tag, whether introduced
142 
				by the developer, user, or an FTP application, can cause unwanted output, PHP errors, or if the latter are suppressed, blank pages.  For this reason, all PHP files should
143 
				<strong>OMIT</strong> the closing PHP tag, and instead use a comment block to mark the end of file and it's location relative to the application root.
144 
				This allows you to still identify a file as being complete and not truncated.</p>
145 
<code><strong>INCORRECT</strong>:
146 
&lt;?php
147 
 
148 
echo "Here's my code!";
149 
 
150 
?&gt;
151 
 
152 
<strong>CORRECT</strong>:
153 
&lt;?php
154 
 
155 
echo "Here's my code!";
156 
 
157 
/* End of file myfile.php */
158 
/* Location: ./system/modules/mymodule/myfile.php */
159 
</code>
160 
		</div>
161 
 
162 
 
163 
		<h2><a name="class_and_method_naming"></a>Class and Method Naming</h2>
164 
		<div class="guidelineDetails">
165 
			<p>Class names should always have their first letter uppercase, and the constructor method should match identically.  Multiple words should be separated with an underscore, and not CamelCased.  All other class methods should be entirely lowercased and named to clearly indicate their function, preferably including a verb.  Try to avoid overly long and verbose names.</p>
166 
 
167 
	<code><strong>INCORRECT</strong>:
168 
class superclass
169 
class SuperClass
170 
 
171 
<strong>CORRECT</strong>:
172 
class Super_class</code>
173 
 
174 
			<p>Notice that the Class and constructor methods are identically named and cased:</p>
175 
 
176 
	<code>class Super_class {
177 
 
178 
	function Super_class()
179 
	{
180 
 
181 
	}
182 
}</code>
183 
 
184 
			<p>Examples of improper and proper method naming:</p>
185 
 
186 
	<code><strong>INCORRECT</strong>:
187 
function fileproperties()		// not descriptive and needs underscore separator
188 
function fileProperties()		// not descriptive and uses CamelCase
189 
function getfileproperties()		// Better!  But still missing underscore separator
190 
function getFileProperties()		// uses CamelCase
191 
function get_the_file_properties_from_the_file()	// wordy
192 
 
193 
<strong>CORRECT</strong>:
194 
function get_file_properties()	// descriptive, underscore separator, and all lowercase letters</code>
195 
 
196 
		</div>
197 
 
198 
 
199 
		<h2><a name="variable_names"></a>Variable Names</h2>
200 
		<div class="guidelineDetails">
201 
			<p>The guidelines for variable naming is very similar to that used for class methods.  Namely, variables should contain only lowercase letters, use underscore separators, and be reasonably named to indicate their purpose and contents. Very short, non-word variables should only be used as iterators in for() loops.</p>
202 
<code><strong>INCORRECT</strong>:
203 
$j = &apos;foo&apos;;		// single letter variables should only be used in for() loops
204 
$Str			// contains uppercase letters
205 
$bufferedText		// uses CamelCasing, and could be shortened without losing semantic meaning
206 
$groupid		// multiple words, needs underscore separator
207 
$name_of_last_city_used	// too long
208 
 
209 
<strong>CORRECT</strong>:
210 
for ($j = 0; $j &lt; 10; $j++)
211 
$str
212 
$buffer
213 
$group_id
214 
$last_city
215 
</code>
216 
		</div>
217 
 
218 
 
219 
		<h2><a name="commenting"></a>Commenting</h2>
220 
		<div class="guidelineDetails">
221 
			<p>In general, code should be commented prolifically.  It not only helps describe the flow and intent of the code for less experienced programmers, but can prove invaluable when returning to your own code months down the line.  There is not a required format for comments, but the following are recommended.</p>
222 
 
223 
			<p><a href="http://manual.phpdoc.org/HTMLSmartyConverter/HandS/phpDocumentor/tutorial_phpDocumentor.howto.pkg.html#basics.docblock">DocBlock</a> style comments preceding class and method declarations so they can be picked up by IDEs:</p>
224 
 
225 
<code>/**
226 
 * Super Class
227 
 *
228 
 * @package	Package Name
229 
 * @subpackage	Subpackage
230 
 * @category	Category
231 
 * @author	Author Name
232 
 * @link	http://example.com
233 
 */
234 
class Super_class {</code>
235 
 
236 
<code>/**
237 
 * Encodes string for use in XML
238 
 *
239 
 * @access	public
240 
 * @param	string
241 
 * @return	string
242 
 */
243 
function xml_encode($str)</code>
244 
 
245 
			<p>Use single line comments within code, leaving a blank line between large comment blocks and code.</p>
246 
 
247 
<code>// break up the string by newlines
248 
$parts = explode("\n", $str);
249 
 
250 
// A longer comment that needs to give greater detail on what is
251 
// occurring and why can use multiple single-line comments.  Try to
252 
// keep the width reasonable, around 70 characters is the easiest to
253 
// read.  Don't hesitate to link to permanent external resources
254 
// that may provide greater detail:
255 
//
256 
// http://example.com/information_about_something/in_particular/
257 
 
258 
$parts = $this->foo($parts);
259 
</code>
260 
		</div>
261 
 
262 
 
263 
		<h2><a name="constants"></a>Constants</h2>
264 
		<div class="guidelineDetails">
265 
			<p>Constants follow the same guidelines as do variables, except constants should always be fully uppercase.  <em>Always use ExpressionEngine constants when appropriate, i.e. SLASH, LD, RD, PATH_CACHE, etc.</em></p>
266 
<code><strong>INCORRECT</strong>:
267 
myConstant	// missing underscore separator and not fully uppercase
268 
N		// no single-letter constants
269 
S_C_VER		// not descriptive
270 
$str = str_replace('{foo}', 'bar', $str);	// should use LD and RD constants
271 
 
272 
<strong>CORRECT</strong>:
273 
MY_CONSTANT
274 
NEWLINE
275 
SUPER_CLASS_VERSION
276 
$str = str_replace(LD.'foo'.RD, 'bar', $str);
277 
</code>
278 
		</div>
279 
 
280 
 
281 
		<h2><a name="true_false_and_null"></a>TRUE, FALSE, and NULL</h2>
282 
		<div class="guidelineDetails">
283 
			<p><strong>TRUE</strong>, <strong>FALSE</strong>, and <strong>NULL</strong> keywords should always be fully uppercase.</p>
284 
<code><strong>INCORRECT</strong>:
285 
if ($foo == true)
286 
$bar = false;
287 
function foo($bar = null)
288 
 
289 
<strong>CORRECT</strong>:
290 
if ($foo == TRUE)
291 
$bar = FALSE;
292 
function foo($bar = NULL)</code>
293 
		</div>
294 
 
295 
 
296 
 
297 
		<h2><a name="logical_operators"></a>Logical Operators</h2>
298 
		<div class="guidelineDetails">
299 
			<p>Use of <strong>||</strong> is discouraged as its clarity on some output devices is low (looking like the number 11 for instance).
300 
				<strong>&amp;&amp;</strong> is preferred over <strong>AND</strong> but either are acceptable, and a space should always precede and follow <strong>!</strong>.</p>
301 
<code><strong>INCORRECT</strong>:
302 
if ($foo || $bar)
303 
if ($foo AND $bar)  // okay but not recommended for common syntax highlighting applications
304 
if (!$foo)
305 
if (! is_array($foo))
306 
 
307 
<strong>CORRECT</strong>:
308 
if ($foo OR $bar)
309 
if ($foo && $bar) // recommended
310 
if ( ! $foo)
311 
if ( ! is_array($foo))
312 
</code>
313 
		</div>
314 
 
315 
 
316 
 
317 
		<h2><a name="comparing_return_values_and_typecasting"></a>Comparing Return Values and Typecasting</h2>
318 
		<div class="guidelineDetails">
319 
			<p>Some PHP functions return FALSE on failure, but may also have a valid return value of "" or 0, which would evaluate to FALSE in loose comparisons.  Be explicit by comparing the variable type when using these return values in conditionals to ensure the return value is indeed what you expect, and not a value that has an equivalent loose-type evaluation.</p>
320 
			<p>Use the same stringency in returning and checking your own variables.  Use <strong>===</strong> and <strong>!==</strong> as necessary.
321 
 
322 
<code><strong>INCORRECT</strong>:
323 
// If 'foo' is at the beginning of the string, strpos will return a 0,
324 
// resulting in this conditional evaluating as TRUE
325 
if (strpos($str, 'foo') == FALSE)
326 
 
327 
<strong>CORRECT</strong>:
328 
if (strpos($str, 'foo') === FALSE)
329 
</code>
330 
 
331 
<code><strong>INCORRECT</strong>:
332 
function build_string($str = "")
333 
{
334 
	if ($str == "")	// uh-oh!  What if FALSE or the integer 0 is passed as an argument?
335 
	{
336 
 
337 
	}
338 
}
339 
 
340 
<strong>CORRECT</strong>:
341 
function build_string($str = "")
342 
{
343 
	if ($str === "")
344 
	{
345 
 
346 
	}
347 
}</code>
348 
 
349 
		<p>See also information regarding <a href="http://us3.php.net/manual/en/language.types.type-juggling.php#language.types.typecasting">typecasting</a>, which can be quite useful.  Typecasting has a slightly different effect which may be desirable.  When casting a variable as a string, for instance, NULL and boolean FALSE variables become empty strings, 0 (and other numbers) become strings of digits, and boolean TRUE becomes "1":</p>
350 
 
351 
<code>$str = (string) $str;	// cast $str as a string</code>
352 
 
353 
		</div>
354 
 
355 
 
356 
		<h2><a name="debugging_code"></a>Debugging Code</h2>
357 
		<div class="guidelineDetails">
358 
			<p>No debugging code can be left in place for submitted add-ons unless it is commented out, i.e. no var_dump(), print_r(), die(), and exit() calls that were used while creating the add-on, unless they are commented out.</p>
359 
 
360 
<code>// print_r($foo);</code>
361 
		</div>
362 
 
363 
 
364 
 
365 
		<h2><a name="whitespace_in_files"></a>Whitespace in Files</h2>
366 
		<div class="guidelineDetails">
367 
			<p>No whitespace can precede the opening PHP tag or follow the closing PHP tag.  ExpressionEngine output is buffered, so whitespace in your files can cause output to begin before ExpressionEngine outputs its content, leading to errors and an inability for ExpressionEngine to send proper headers.  In the examples below, select the text with your mouse to reveal the incorrect whitespace.</p>
368 
 
369 
			<p><strong>INCORRECT</strong>:</p>
370 
<code>
371 
&lt;?php
372 
	// ...there is whitespace and a linebreak above the opening PHP tag
373 
	// as well as whitespace after the closing PHP tag
374 
?&gt;
375 
</code>
376 
			<p><strong>CORRECT</strong>:</p>
377 
<code>&lt;?php
378 
	// this sample has no whitespace before or after the opening and closing PHP tags
379 
?&gt;</code>
380 
 
381 
		</div>
382 
 
383 
 
384 
		<h2><a name="compatibility"></a>Compatibility</h2>
385 
		<div class="guidelineDetails">
386 
			<p>Unless specifically mentioned in your add-on's documentation, all code must be compatible with PHP version 4.3+.  Additionally, do not use PHP functions that require non-default libraries to be installed unless your code contains an alternative method when the function is not available, or you implicitly document that your add-on requires said PHP libraries.</p>
387 
		</div>
388 
 
389 
 
390 
 
391 
		<h2><a name="class_and_file_names_using_common_words"></a>Class and File Names using Common Words</h2>
392 
		<div class="guidelineDetails">
393 
			<p>When your class or filename is a common word, or might quite likely be identically named in another PHP script, provide a unique prefix to help prevent collision.  Always realize that your end users may be running other add-ons or third party PHP scripts.  Choose a prefix that is unique to your identity as a developer or company.</p>
394 
 
395 
<code><strong>INCORRECT</strong>:
396 
class Email		pi.email.php
397 
class Xml		ext.xml.php
398 
class Import		mod.import.php
399 
 
400 
<strong>CORRECT</strong>:
401 
class Pre_email		pi.pre_email.php
402 
class Pre_xml		ext.pre_xml.php
403 
class Pre_import	mod.pre_import.php
404 
</code>
405 
		</div>
406 
 
407 
 
408 
		<h2><a name="database_table_names"></a>Database Table Names</h2>
409 
		<div class="guidelineDetails">
410 
			<p>Any tables that your add-on might use must use the 'exp_' prefix, followed by a prefix uniquely identifying you as the developer or company, and then a short descriptive table name.  You do not need to be concerned about the database prefix being used on the user's installation, as ExpressionEngine's database class will automatically convert 'exp_' to what is actually being used.</p>
411 
 
412 
<code><strong>INCORRECT</strong>:
413 
email_addresses		// missing both prefixes
414 
pre_email_addresses	// missing exp_ prefix
415 
exp_email_addresses	// missing unique prefix
416 
 
417 
<strong>CORRECT</strong>:
418 
exp_pre_email_addresses
419 
</code>
420 
 
421 
			<p class="important"><strong>NOTE:</strong> Be mindful that MySQL has a limit of 64 characters for table names.  This should not be an issue as table names that would exceed this would likely have unreasonable names.  For instance, the following table name exceeds this limitation by one character.  Silly, no? <strong>exp_pre_email_addresses_of_registered_users_in_seattle_washington</strong>
422 
		</div>
423 
 
424 
 
425 
 
426 
		<h2><a name="one_file_per_class"></a>One File per Class</h2>
427 
		<div class="guidelineDetails">
428 
			<p>Use separate files for each class your add-on uses, unless the classes are <em>closely related</em>.  An example of ExpressionEngine files that contains multiple classes is the Database class file, which contains both the DB class and the DB_Cache class, and the Magpie plugin, which contains both the Magpie and Snoopy classes.</p>
429 
		</div>
430 
 
431 
 
432 
 
433 
		<h2><a name="whitespace"></a>Whitespace</h2>
434 
		<div class="guidelineDetails">
435 
			<p>Use tabs for whitespace in your code, not spaces.  This may seem like a small thing, but using tabs instead of whitespace allows the developer looking at your code to have indentation at levels that they prefer and customize in whatever application they use.  And as a side benefit, it results in (slightly) more compact files, storing one tab character versus, say, four space characters.</p>
436 
		</div>
437 
 
438 
 
439 
 
440 
		<h2><a name="line_breaks"></a>Line Breaks</h2>
441 
		<div class="guidelineDetails">
442 
			<p>Files must be saved with Unix line breaks.  This is more of an issue for developers who work in Windows, but in any case ensure that your text editor is setup to save files with Unix line breaks.</p>
443 
		</div>
444 
 
445 
 
446 
 
447 
		<h2><a name="code_indenting"></a>Code Indenting</h2>
448 
		<div class="guidelineDetails">
449 
			<p>Use Allman style indenting.  With the exception of Class declarations, braces are always placed on a line by themselves, and indented at the same level as the control statement that "owns" them.</p>
450 
 
451 
<code><strong>INCORRECT</strong>:
452 
function foo($bar) {
453 
	// ...
454 
}
455 
 
456 
foreach ($arr as $key => $val) {
457 
	// ...
458 
}
459 
 
460 
if ($foo == $bar) {
461 
	// ...
462 
} else {
463 
	// ...
464 
}
465 
 
466 
for ($i = 0; $i &lt; 10; $i++)
467 
	{
468 
	for ($j = 0; $j &lt; 10; $j++)
469 
		{
470 
		// ...
471 
		}
472 
	}
473 
 
474 
<strong>CORRECT</strong>:
475 
function foo($bar)
476 
{
477 
	// ...
478 
}
479 
 
480 
foreach ($arr as $key => $val)
481 
{
482 
	// ...
483 
}
484 
 
485 
if ($foo == $bar)
486 
{
487 
	// ...
488 
}
489 
else
490 
{
491 
	// ...
492 
}
493 
 
494 
for ($i = 0; $i &lt; 10; $i++)
495 
{
496 
	for ($j = 0; $j &lt; 10; $j++)
497 
	{
498 
		// ...
499 
	}
500 
}</code>
501 
		</div>
502 
 
503 
 
504 
	<h2><a name="bracket_spacing"></a>Bracket and Parenthetic Spacing</h2>
505 
		<div class="guidelineDetails">
506 
			<p>In general, parenthesis and brackets should not use any additional spaces.  The exception is that a space should always follow PHP control structures that accept arguments with parenthesis (declare, do-while, elseif, for, foreach, if, switch, while), to help distinguish them from functions and increase readability.</p>
507 
 
508 
<code>INCORRECT:
509 
$arr[ $foo ] = 'foo';
510 
 
511 
CORRECT:
512 
$arr[$foo] = 'foo'; // no spaces around array keys
513 
 
514 
 
515 
INCORRECT:
516 
function foo ( $bar )
517 
{
518 
 
519 
}
520 
 
521 
CORRECT:
522 
function foo($bar) // no spaces around parenthesis in function declarations
523 
{
524 
 
525 
}
526 
 
527 
 
528 
INCORRECT:
529 
foreach( $query->result() as $row )
530 
 
531 
CORRECT:
532 
foreach ($query->result() as $row) // single space following PHP control structures, but not in interior parenthesis
533 
</code>
534 
		</div>
535 
 
536 
 
537 
 
538 
		<h2><a name="localized_text_in_control_panel"></a>Localized Text in Control Panel</h2>
539 
		<div class="guidelineDetails">
540 
			<p>Any text that is output in the control panel should use language variables in your module's lang file to allow localization.</p>
541 
 
542 
<code>INCORRECT:
543 
return "Invalid Selection";
544 
 
545 
CORRECT:
546 
return $LANG->line('invalid_selection');</code>
547 
		</div>
548 
 
549 
 
550 
 
551 
		<h2><a name="private_methods_and_variables"></a>Private Methods and Variables</h2>
552 
		<div class="guidelineDetails">
553 
			<p>Methods and variables that are only accessed internally by your class, such as utility and helper functions that your public methods use for code abstraction, should be prefixed with an underscore.</p>
554 
 
555 
<code>convert_text()		// public method
556 
_convert_text()		// private method</code>
557 
		</div>
558 
 
559 
 
560 
 
561 
		<h2><a name="php_errors"></a>PHP Errors</h2>
562 
		<div class="guidelineDetails">
563 
			<p>Code must run error free and not rely on warnings and notices to be hidden to meet this requirement.  For instance, never access a variable that you did not set yourself (such as $_POST array keys) without first checking to see that it isset().</p>
564 
 
565 
			<p>Make sure that while developing your add-on, error reporting is enabled for ALL users, and that display_errors is enabled in the PHP environment.  You can check this setting with:</p>
566 
 
567 
<code>if (ini_get('display_errors') == 1)
568 
{
569 
	exit "Enabled";
570 
}</code>
571 
 
572 
			<p>On some servers where display_errors is disabled, and you do not have the ability to change this in the php.ini, you can often enable it with:</p>
573 
 
574 
<code>ini_set('display_errors', 1);</code>
575 
 
576 
			<p class="important"><strong>NOTE:</strong> Setting the <a href="http://us.php.net/manual/en/ref.errorfunc.php#ini.display-errors">display_errors</a> setting with ini_set() at runtime is not identical to having it enabled in the PHP environment.  Namely, it will not have any effect if the script has fatal errors</p>
577 
		</div>
578 
 
579 
 
580 
 
581 
		<h2><a name="short_open_tags"></a>Short Open Tags</h2>
582 
		<div class="guidelineDetails">
583 
			<p>Always use full PHP opening tags, in case a server does not have short_open_tag enabled.</p>
584 
 
585 
<code><strong>INCORRECT</strong>:
586 
&lt;? echo $foo; ?&gt;
587 
 
588 
&lt;?=$foo?&gt;
589 
 
590 
<strong>CORRECT</strong>:
591 
&lt;?php echo $foo; ?&gt;</code>
592 
		</div>
593 
 
594 
 
595 
 
596 
		<h2><a name="one_statement_per_line"></a>One Statement Per Line</h2>
597 
		<div class="guidelineDetails">
598 
			<p>Never combine statements on one line.</p>
599 
 
600 
<code><strong>INCORRECT</strong>:
601 
$foo = 'this'; $bar = 'that'; $bat = str_replace($foo, $bar, $bag);
602 
 
603 
<strong>CORRECT</strong>:
604 
$foo = 'this';
605 
$bar = 'that';
606 
$bat = str_replace($foo, $bar, $bag);
607 
</code>
608 
		</div>
609 
 
610 
 
611 
 
612 
		<h2><a name="strings"></a>Strings</h2>
613 
		<div class="guidelineDetails">
614 
			<p>Always use single quoted strings unless you need variables parsed, and in cases where you do need variables parsed, use braces to prevent greedy token parsing.  You may also use double-quoted strings if the string contains single quotes, so you do not have to use escape characters.</p>
615 
 
616 
<code><strong>INCORRECT</strong>:
617 
"My String"					// no variable parsing, so no use for double quotes
618 
"My string $foo"				// needs braces
619 
'SELECT foo FROM bar WHERE baz = \'bag\''	// ugly
620 
 
621 
<strong>CORRECT</strong>:
622 
'My String'
623 
"My string {$foo}"
624 
"SELECT foo FROM bar WHERE baz = 'bag'"</code>
625 
		</div>
626 
 
627 
 
628 
 
629 
		<h2><a name="sql_queries"></a>SQL Queries</h2>
630 
		<div class="guidelineDetails">
631 
			<p>MySQL keywords are always capitalized: SELECT, INSERT, UPDATE, WHERE, AS, JOIN, ON, IN, etc.</p>
632 
 
633 
			<p>Break up long queries into multiple lines for legibility, preferably breaking for each clause.</p>
634 
 
635 
<code><strong>INCORRECT</strong>:
636 
// keywords are lowercase and query is too long for
637 
// a single line (... indicates continuation of line)
638 
$query = $this->db->query("select foo, bar, baz, foofoo, foobar as raboof, foobaz from exp_pre_email_addresses
639 
...where foo != 'oof' and baz != 'zab' order by foobaz limit 5, 100");
640 
 
641 
<strong>CORRECT</strong>:
642 
$query = $this->db->query("SELECT foo, bar, baz, foofoo, foobar AS raboof, foobaz
643 
				FROM exp_pre_email_addresses
644 
				WHERE foo != 'oof'
645 
				AND baz != 'zab'
646 
				ORDER BY foobaz
647 
				LIMIT 5, 100");</code>
648 
		</div>
649 
 
650 
 
651 
 
652 
		<h2><a name="default_function_arguments"></a>Default Function Arguments</h2>
653 
		<div class="guidelineDetails">
654 
			<p>Whenever appropriate, provide function argument defaults, which helps prevent PHP errors with mistaken calls and provides common fallback values which can save a few lines of code. Example:</p>
655 
 
656 
<code>function foo($bar = '', $baz = FALSE)</code>
657 
		</div>
658 
 
659 
 
660 
 
661 
		<h2><a name="overlapping_tag_parameters"></a>Overlapping Tag Parameters</h2>
662 
		<div class="guidelineDetails">
663 
			<p>Avoid multiple tag parameters that have effect on the same thing.  For instance, instead of <strong>include=</strong> and <strong>exclude=</strong>, perhaps allow <strong>include=</strong> to handle the parameter alone, with the addition of "not", e.g. <strong>include="not bar"</strong>.  This will prevent problems of parameters overlapping or having to worry about which parameter has priority over another.</p>
664 
		</div>
665 
 
666 
 
667 
</div>
668 
 
669 
 
670 
 
671 
</div>
672 
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673 
 
674 
 
675 
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676 
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677 
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678 
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679 
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680 
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681 
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682 
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683 
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685 
 
686 
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687 
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