Background
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If you’re creating an application from ground up, you may already have coded or even designed the core components to check for and avoid non-traversable parameters in some methods or functions that use these variables in foreach statements within them. However, if you are modifying an existing and unfamiliar application you would want to keep the changes localized to avoid affecting other parts of the program. In the case for foreach, a simple check of the arguments can be performed on them before passing to the looping construct.
This article demonstrates how to perform checking on a variable to determine whether it is traversable to not before letting foreach use it.
Software Requirements
- Windows 7 Professional SP1
- PHP 5.5.9 / Zend Engine v2.5.0
- NetBeans IDE 8.0.1
The Codes
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | /* * Copyright 2014 www.turreta.com. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /** * Description of ForEachInvalidArgumentFixDemp * * @author www.turreta.com */ class ForEachInvalidArgumentFixDemp { public $last_name = 'Smith'; public $first_name = 'John'; public $middle_name = 'Head'; public function do_stuff() { } } /** * Determine if a variable is iterable. i.e. can be used to loop over. * * @return bool */ function is_iterable($var) { $bIsIteratble = false; if($var !== null && (is_array($var) || $var instanceof Traversable || $var instanceof Iterator || $var instanceof IteratorAggregate || (is_object($var) && count(get_object_vars($var)) > 0 ))) { $bIsIteratble = true; } return $bIsIteratble; } var_dump(is_iterable('turreta.com')); var_dump(is_iterable(123)); var_dump(is_iterable(['tu','rre', 'ta', '.com'])); var_dump(is_iterable(new SplDoublyLinkedList())); var_dump(is_iterable(new ArrayIterator())); var_dump(is_iterable(new ForEachInvalidArgumentFixDemp())); // Sample usage with foreach $oSample = new ForEachInvalidArgumentFixDemp(); if(is_iterable($oSample)) { foreach($oSample as $key => $val) { echo $key . " = " . $val . "\n"; } } |
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