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OPINIE UŻYTKOWNIKÓW
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Uważam, że serwis jest najlepszy na świecie. Wykonany rzetelnie, a wszystkie skrypty sa dopracowane. Zamieszczony materiał godny mistrza. Jestem programistą od wielu lat i bez tego serwisu nie istnieje. Upraszacza życie każdemu programiście. Imponujący jest fakt, że do twórcy serwisu zawsze można się zwrócić z prośbą o pomoc i uzyskuje się ją w bardzo krótkim czasie. Najważniejsze w tym wszystkim jest to, że można korzystać z witryny za symboliczną opłatą.
Marcin Kowalski
Multinet Polska
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PODRĘCZNIK PHP 5.x, 4.x, 3.x - częściowo spolszczony / źródło: www.php.net
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XL. Function Handling Functions
These functions all handle various operations involved in working
with functions.
Do zbudowania tego rozszerzenia nie są wymagane
żadne zewnętrzne biblioteki. By używać tych funkcji, nie trzeba niczego instalować.
Są one częścią jądra PHP. To rozszerzenie nie definiuje posiada żadnych
dyrektyw konfiguracyjnych w pliku php.ini. To rozszerzenie nie posiada żadnych stałych.
User Contributed NotesMichael T. McGrew
12-May-2005 06:56
An interesting way to use functions is by putting other things than PHP in them, i.e. HTML CSS. This can be useful if you will be using a format for many pages. Yes, the include function can be used also, but by defining them in functions can make them more portable in a way and keep you from having to make many include files. You could use include() when one will be putting big portions of PHP, HTML, and/or CSS and will be using them in many pages. Then you could use PHP, HTML, and/or CSS in a function when it is smaller portions of code and only want it to be on a few pages.
I have been using include() for HTML and CSS in my early days of PHP coding, but I will be using functions for that a lot more now.
<?php function a() { ?>
<style type="text/css">
table {
border: 1px dashed black;
background: #95EAFE;
text-align:left;
width:610px;
}
.linkbar {
font-family:sans-serif;
line-height:40px;
top:1px;
text-align:center;
width:200px;
height:10px;
}
</style>
<?php } ?>
Now doing:
<?php a(); ?>
will return all of the CSS just as if you had wrote it on the actual page, or used include() . The same thing goes for HTML code inside a function. The possibilities are endless...
michael dot bommarito at gmail dot com
30-Jan-2005 08:28
I've developed an easy-to-use hack using these functions to emulate overloaded functions. It's especially handy for constructors and/or C++ style templating.
Here's a little example to get you going. This does the trick for most circumstances, and if you need more intelligent parsing, it's not too hard to implement with regex or a more suitable classification scheme.
N.B. Note the lack of whitespace between variable types in case strings.
class Matrix {
...
function Matrix() {
$args = func_get_args();
$argmatch = implode(",", array_map('gettype', $args));
switch( $argmatch ) {
case 'integer,integer':
//initialize m x n matrix
break;
case 'integer,integer,integer':
//initialize m x n matrix with constant c
break;
case 'integer,integer,float':
//initialize m x n matrix with constant c
break;
case 'array':
//initialize from array (2D....)
break;
case 'array,integer':
//intialize from array (1D packed with m rows)
break;
default:
//(void) overload?
//error handling?
break;
}
}
...
}
php-note-2003-june-18 at ryandesign dot com
18-Jun-2003 05:22
Xavier's example is rather complicated, and his task would be much more simply accomplished by using classes. Define a base class to do the basic functions open, dump, and close, and create extension classes to override whatever behavior.
class foo {
function open() {
// Default functionality for open()
}
function dump() {
// Default functionality for dump()
}
function close() {
// Default functionality for close()
}
}
class bar extends foo {
function open() {
// Override functionality of open()
}
// dump() and close() remain as in class foo
}
xmontero at dsitelecom dot com
23-Aug-2002 11:49
You can do some kind of overloading functions in PHP using "function_exists".
Let's suppose you want a script to call plugins that are php files and you want the plugins to "override" behaviours that if not overriden are used by default.
You might for example write a "mySQL table viewer" which displays a table and it "opens a table", "dumps the header", "dumps row-by-row" and then "closes the table".
Let's suppose you want a plugin for "Stocks" which prints negative stocks in red, so you want to override the "dumping row-by-row" to do that behaviour. Instead you do not want to have all the "default behaviour" repeated in the plugin.
You may then do the following:
1) Define a default plugin (ex: "default.php"
2) Write all your functions in default.php to open, dump and close, but add them a suffix:
open_table_default()
dump_header_default()
dump_row_default()
close_table_default()
3) Call your functions with a wrapper: Insetad of this:
open_table() or open_table_default() write this:
plugincall("open_table");
4) Then write a function called plugincall which uses function_exists() to see if you call one or the other function:
function plugincall($desired_function_name)
{
if( function_exists( $desired_function_name))
{
//Call the plugin
//Note the $ before the name
$desired_function_name()
}
else
{
$desired_function_name = $desired_function_name . "_default";
if( function_exists($desired_function_name))
{
//Call the default
//Note the $ before the name
$desired_function_name()
}
else
{
// Nor the plugin nor the default were defined
}
}
So, now, if the require_once(plugin.php) contains a function called "open_table()", it will be used. Instaed, "open_table_default()" will be used.
It's not like overloading functions, but it is very useful to write scripts ampliable by other programmers: If they write a function, it is used, if not, the default is used.
See ya!
Xavier Montero.
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