Call static method with class name stored as instance variable

Question

Consider this script

class B
{
    static public function hi() { echo "hi\n"; }
}
class A
{
    private $name = 'B';

    public function __construct()
    {
        // This doesn't parse
        // $this->name::hi();

        // But this works fine
        $class = $this->name;
        $class::hi();
    }
}
new A();

Any idea how/if I could get the first example $this->name::hi(); to parse and work?

What version of PHP do you have? $class::hi() should work in 5.3. — Barmar
– Barmar, Commented Oct 23, 2014 at 1:36
he is saying // But this works fine is working fine whats not working is the other one i think its not clear — mahen3d
– mahen3d, Commented Oct 23, 2014 at 1:37
@Barmar yes, he already said that, what does not work is $this->$name::hi(), looks like it should be $this->name, that's probably the problem. — King King
– King King, Commented Oct 23, 2014 at 1:37
i think its becos $name is just variables you havent assigned the class B to that var yet.. — mahen3d
– mahen3d, Commented Oct 23, 2014 at 1:39
Is it really so bad to have to create a variable first? Why do people need to turn everything into one-liners? — Barmar
– Barmar, Commented Oct 23, 2014 at 1:42

Vitalii Fedorenko · Accepted Answer · 2014-10-24 01:26:04Z

2

The current implementation of Zend PHP parser supports only static method calls that are made directly on a class name or a variable. Here is the grammar:

%token T_PAAMAYIM_NEKUDOTAYIM ":: (T_PAAMAYIM_NEKUDOTAYIM)"

function_call:
    name argument_list
        { $$ = zend_ast_create(ZEND_AST_CALL, $1, $2); }
|   class_name T_PAAMAYIM_NEKUDOTAYIM member_name argument_list
        { $$ = zend_ast_create(ZEND_AST_STATIC_CALL, $1, $3, $4); }
|   variable_class_name T_PAAMAYIM_NEKUDOTAYIM member_name argument_list
        { $$ = zend_ast_create(ZEND_AST_STATIC_CALL, $1, $3, $4); }
|   callable_expr argument_list
        { $$ = zend_ast_create(ZEND_AST_CALL, $1, $2); }

Source: https://github.com/php/php-src/blob/master/Zend/zend_language_parser.y#L890

answered Oct 24, 2014 at 1:26

Vitalii Fedorenko

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1 Comment

quickshiftin Over a year ago

Thanks, this is the kind of answer I was looking for.

Ohgodwhy · Accepted Answer · 2014-10-23 01:48:34Z

-1

Given that in your current circumstances you require a method of the class b within the class a, it seems pretty anti intuitive to approach it this way. Further, the the availability to call a method of another class is simply not there, you would need to use:

call_user_func(array($this->name, 'hi'));

one way is to simply require the B class as a depency of the constructor function of the A class:

class B
{
    static public function hi() { echo "hi\n"; }
}

class A
{
    private $b;

    public function __construct(B $b)
    {

        $b::hi();

    }
}
new A(new B);

This is probably as close to the one liner approach that you're looking for that you can get.

answered Oct 23, 2014 at 1:48

Ohgodwhy

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1 Comment

quickshiftin Over a year ago

This doesn't really answer my question, and actually changes the semantics anyway b/c I don't have an instance of B, I just want to refer to the class B, specifically through a string stored in an instance variable of another class.

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