Re: optional object arguments to a function

Nathan Rixham wrote: > Shawn McKenzie wrote: >> Michael A. Peters wrote: >>> Rene Veerman wrote: >>>> On Sat, Feb 13, 2010 at 9:05 AM, Michael A. Peters <mpeters@mac.com> >>>> wrote: >>>>> How do I specify a default null object, or otherwise make the argument >>>>> argument optional? >>>>> >>>> To my knowledge: can't be done. >>>> >>>> But you can check any args through the func_get_arg*() functions, then >>>> per-parameter push 'm through a check function that checks if their >>>> primary properties are set. >>>> It's equivalent to checking for null ( / bad) objects. >>>> >>> Thank you to everybody. I think I will see how far I can get with >>> func_get_arg - it may solve the problem. >>> >>> The other hackish solution I thought of is to put the object arguments >>> into a key/value array and pass the array as a single argument to the >>> function. That way I can check for the key and if the key is set, grab >>> the object associated with it. >> Maybe I mis-read your post, but what's wrong with Jochem's method. >> That's what I was going to propose. >> > > This is a problem with php; you can't do the following (since object > isn't a class): > function test( object $o = null ) > > so normally you'd do: > function test( stdClass $o = null ) > > but this only works for stdClass - (object)"something" and *not* > instances of classes: > > <?php > class Foo {} > $o = new Foo(); > test( $foo ); > ?> > > will fail because Foo is not an instance of stdClass > > in short there is no way (in PHP) to type hint that something should be > an object of any class. > > thus you have two options to work around this; option 1: > > check yourself: > function test( $o = null ) { > if( $o !== null && !is_object($o) ) { > throw new InvalidArgumentException( '$o must be an object' ); > } > } > > ensure you always only use instances of classes and not just > "objects/stdClass" (or make everything extend stdClass <stupid>) > > back to the main question - How do I specify a default null object - > like this: > > function foo($a='',$b='',$c=false, $o=null) { > if( $o !== null && !is_object($o) ) { > throw new InvalidArgumentException( '$o must be an object' ); > } > // in the same way a you'd do > if( !is_string($a) ) { > throw new InvalidArgumentException( '$a must be a string' ); > } > } > > side note: if you're finding you may need an unknown number of arguments > then other than refactoring all your design to handle one argument at a > time to avoid cross cutting concerns, then you're stuck with > func_get_arg and checking each argument as you go; not strict but if it > works and it's fast.. > > feel like I've just typed "blah blah blah" for the last 10 minutes, ahh > well ho hum! > > regards :) I guess I missed the part where he wasn't going to know what class the object was from. I would think you would normally know. function foo($a = '', $b = '', $c = false, myClass $o = null) -- Thanks! -Shawn http://www.spidean.com