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Diffstat (limited to 'ext/spl/README')
| -rwxr-xr-x | ext/spl/README | 94 |
1 files changed, 16 insertions, 78 deletions
diff --git a/ext/spl/README b/ext/spl/README index 60c6d97425..99f34af679 100755 --- a/ext/spl/README +++ b/ext/spl/README @@ -1,88 +1,26 @@ This is an extension that aims to implement some efficient data access interfaces and classes. You'll find the classes documented using php -code in the file spl.php. +code in the file spl.php or in the corresponding .inc file in the examples +subdirectory. Based on the internal implementations or the files in the +examples subdirectory there are also some .php files to experiment with. -There are special SPL interfaces that provides the ability to hook into -foreach and array reading/writng. By inheriting these interfaces, instances -of the resulting classes can be iterated using the foreach construct or -use array read write notation. - -Look into the examples subdirectory for some basic examples which will -demonstracte this. - -Also some classes of extensions like SQLite inherit SPL interfaces so that -they take advantage of the foreach or array overloading. +The .inc files are not included automatically because the are sooner or +later intergrated into the extension. That means that you either need to +put the code of examples/autoload into your autoprepend file or that you +have to point your ini setting auto_prepend_file to this file. 1) Iterators -Iterator is design pattern that allows to enumerate and list all elements of -a collection whatsoever using an oo protocol. The minimalistic Iterator needs -a method that returns the current value, a method that moves to the next value -and a method that checks whether or not the Iterator can provide more elements. - -In SPL this basich Iterator is defined by the interface spl_forward: - -interface spl_forward { - function current(); - function next(); - function has_more(); -} - -This basic Iterator does not allow to rewind itself nor does it in anyway -support to name the values by some kind association as key/value mappings -provided by the standard PHP arrays. All these additions to the basic Iterator -are done in specialized interfaces as described in detail in the file spl.php. - -SPL allows to hook into the engine opcodes that realize the foreach construct. -This construct normally works on arrays the following way. First it rewinds -the current array position to the beginning. Then it loops through the whole -array by first checking whether or not the end of the array is reached and -if not returning the current array value and or key. After that it move the -current array pointer forward and does starts the loop process again. As you -can see this perfectly maps to the interface spl_forward. So the foreach -hooking simply checks whether or not the variable passed to foreach is an -object of a class implementing the interface spl_forward. The foreach hook -can be activated by --enable-spl-foreach which is on by default. - -class it implements spl_forward... -$obj = new it(); -foreach($obj as $value) ... - -2) Arrays - -Arrays in general, not specifically PHP arrays, provide a collection of pairs -normally referred to as key and value. A PHP object consists of properties and -a class type specifing the methods available for the object. SPL now allows -this to be combined using the spl_array_<xy> interfaces. - -The minimalistic array interface is spl_array_read which only support reading: - -interface spl_array_read { - function exists($key); - function get($key); -} - -Any instance of a class that implements spl_array_read can be used with array -read notation when the corresponding hook is activated --enable-spl-array-read. - -class ar implements spl_array_read... -$obj = new ar(); -$value = $obj[$key]; - -SPL also supports the write notation by the interface spl_array_access: +SPL offers some advanced iterator algorythmns: -interface spl_array_access extends spl_array_read { - function set($value, $index); -} +interface RecursiveIterator implements Iterator +class RecursiveIteratorIterator implements Iterator +abstract class FilterIterator implements Iterator +class ParentIterator extends FilterIterator implements RecursiveIterator -When the array write hook is activated by --enable-spl-array-write the -following can be done: +2) Directories -class ar implements spl_array_access... -$obj = new ar(); -$value = $obj[$key]; -$obj[$key] = $value; +SPL offers two advanced directory classes. -However this hook should only be activated when it is made use of, since it -slows down noticeable. That is the case because first there is some not used -overhead and second the overhead is in one the most often used opcodes.
\ No newline at end of file +class DirectoryIterator implements Iterator +class RecursiveDirectoryIterator extends DirectoryIterator implements RecursiveIterator |