Fwd: Re: [php-objects] assign to $this in constructor.

Forwading this msg to pear-dev and pear-general too. --- "Jesus M. Castagnetto" <jcastagnetto@yahoo.com> wrote: > Date: Wed, 1 Jan 2003 13:44:58 -0800 (PST) > From: "Jesus M. Castagnetto" <jcastagnetto@yahoo.com> > Subject: Re: [php-objects] assign to $this in constructor. > To: php-objects@yahoogroups.com > > > --- Matt Friedman <matt@sprynewmedia.com> wrote: > > I think I was once able to assign to the $this reference in the > > constructor of a php class so that the new operator would return the > > object I've assigned rather than the object requested. I don't seem to > > be able to do this anymore. Is this new in 4.3? > > The previous behaviour sounds to me like the bug ;-). Usually when I need to > handle this dynamic creation of objects, I use a factory method from a > manager > class. It could be from an instance of the manager class or from a static > method from a class. > > The code below has been tested on 3 versions of PHP (4.1.2, 4.3.0 and > 4.4.0-dev > from CVS), none returns an "Error" object, but a "Foo" object. > > > class Error { > var $msg; > function Error($msg) { > $this->msg = $msg; > } > } > > class Foo { > var $n; > function &Foo($n) { > if ($n < 0) { > $this =& new Error('Foo does not like that negative stuff'); > } else { > $this->n = $n; > } > } > } > > $a = new Foo(-1); > print_r($a); > > The ouput is as follows: > > 4.1.2: > > foo Object > ( > ) > > 4.3.0 and 4.4.0-dev from CVS: > > foo Object > ( > [n] => > ) > > > > Is there anyway to alter what object is returned from a php class > > constructor? > > Nope. BTW, do you know of an OOP pattern, construct or language that allows > you > do that. I would like to learn. > > > For instance, there might have been an error so you would return an > > error object instead of the requested object. > > Why not use a class organization like the one below. > > class Error { > var $msg; > function Error($msg) { > $this->msg = $msg; > } > } > > class Foo { > var $n; > function &Foo($n) { > $this->n = $n; > } > } > > class Factory { > function &createFoo($n) { > if ($n < 0) { > return new Error('Foo does not like negatives'); > } else { > return new Foo($n); > } > } > } > > $a =& Factory::createFoo(-1); > print_r($a); > > > This will generate the correct output in all three version I've tried: > > error Object > ( > [msg] => Foo does not like negatives > ) > > The other upside benefit is that you can easily use a method that accepts the > type of object to create, and parameters, etc. Suggested reading are the book > "Design Patterns: Elements of Reusable Object-Oriented Software" and the web > site: http://hillside.net/patterns/ > > > Thanks, > > > > Matt Friedman > > HTH. Will also look at your bug report and proceed accordingly. > > Cheers. > > ===== > --- Jesus M. Castagnetto (jcastagnetto@yahoo.com) > > Research: > http://metallo.scripps.edu/ > Personal: http://www.castagnetto.org/ > > __________________________________________________ > Do you Yahoo!? > Yahoo! Mail Plus - Powerful. Affordable. Sign up now. > http://mailplus.yahoo.com > ===== --- Jesus M. Castagnetto (jcastagnetto@yahoo.com) Research: http://metallo.scripps.edu/ Personal: http://www.castagnetto.org/ __________________________________________________ Do you Yahoo!? Yahoo! Mail Plus - Powerful. Affordable. Sign up now. http://mailplus.yahoo.com