Re: optional object arguments to a function
| From: | Jochem Maas | Date: | Sat, 13 Feb 2010 10:07:15 +0000 |
| Subject: | Re: optional object arguments to a function | ||
| References: | 1 | Groups: | php.general |
| Request: | Send a blank email to php-general+get-302061@lists.php.net to get a copy of this message | ||
Op 2/13/10 8:05 AM, Michael A. Peters schreef:
> I've started working on a class using DOMDocument to assemble MathML in
> php. The class, assuming I actually succeed, will eventually be used for
> parsing LaTeX math equations to MathML without the need to have TeX
> installed. I probably won't be able to support all the possibilities for
> equations that LaTeX does w/o a TeX install (and definitely not user
> defined macros) but I suspect I can (hopefully) cover most of the common
> stuff.
>
> One thing I don't know how to do, though, is write a function where
> arguments are optional object.
>
> IE for a function to generate an integral, the limits are optional but
> if specified must be an object (since they may be an equation
> themselves). I want the default to be some kind of a null object so I
> know to do nothing with it if it is null.
>
> With string/integer you just do
>
> function foo($a='',$b='',$c=false) {
> }
>
> How do I specify a default null object, or otherwise make the argument
> argument optional?
this first one doesn't work:
<?
class Foo
{
function dobar(stdObject $o = null) { /* ... */ }
}
$e = new Foo;
$f = new Foo;
$f->dobar(); // works
$f->dobar($e); // catchable fatal
$f->dobar((object)array()); // catchable fatal - check the error msg!?!?
?>
... but if you're able/willing to specify a user defined class then you
have this option:
<?php
class Bar {}
class Foo
{
function dobar(Bar $o = null) { /* ... */ }
}
$b = new Bar;
$f = new Foo;
$f->dobar($b);
$f->dobar();
?>
>