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Posted by amygdala on 04/13/07 01:39
* top posting fixed *
"Henk verhoeven" <news1@phpPeanus_RemoveThis.org> schreef in bericht
news:evmc7c$qdp$1@news2.zwoll1.ov.home.nl...
> amygdala schreef:
>> I'm trying to figure out the correct use of references.
>>
>> Lets say I have a class Validator and a class User. And I want to let a
>> User instance be an referenced object in Validator. Where would the best
>> place be to put the & sign, and why? (See the /* */ comments inside code)
>>
>> class Validator
>> {
>> public function __construct( /* here? */ $caller )
>> {
>> $this->class =/* here? */ $caller;
>> }
>> }
>>
>> class User
>> {
>> $private validator = NULL;
>> public function __construct()
>> {
>> $this->validator = new Validator( /* or here? */ $this );
>> }
>> }
>>
>> Also, what would happen if were to put & signs in multiple places
>> sprecified in this particular example? Would it be redundant?
>>
>> Thank you for any insight.
> Hi amygdala,
>
> In fact only variables are referenced when using &, not objects or values.
>
> There are four places where you can put the & sign, each has a different
> effect:
> 1. After the = of an assignment,
> 2. Before the name of a function in the function declaration
> 3. Before the name of a parameter declaration in a function declaration
> 4. Before the name of a variable in a function call.
>
> The first makes the assignment assign a reference instead of a value,
> The second makes a function return by reference instead of by value,
> The third makes a parameter to be passed by reference instead of by value
> whenever the function is called
> The fourth forces a parameter to be passed by reference only for the
> specific function call.
>
> The fourh is depricated and will trigger a warning if
> allow_call_time_pass_reference = Off in php.ini.
>
> If you use php5 objects are automatically passed by reference, you don't
> need the & sign for that. In php4 there is no choice you can only mimic
> object references by referencing variables that hold objects. This can be
> tricky, if you can you better use php5.
>
> Using references inapropriately may cause crashes and reference
> anomalies*. For this reason php 4.4 and php 5.1 trigger notifications if a
> value instead of a variable is assigned or passed by reference. If you use
> references consider to use one one of these with error_reporting set to
> E_ALL.
>
> Greetings,
>
> Henk Verhoeven,
> www.phpPeanuts.org
>
> *
> http://www.phppeanuts.org/site/index_php/Pagina/167/reference+anomaly.html
>
> calling the following and using the result has a good chance to crash php:
>
> function &badOne() {
> return $uninitializedVariable;
> }
>
I am indeed using PHP 5. I didn't know that objects are referenced by
default. Good to know. Dank je! (Thank you).
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