使用匿名函数分配属性值

Question

My class is like this:

<?php

class ExampleClass{

    private $example_property = false;

    public function __construct(){
        $this->example_property = function() {
            $this->example_property = 1;
            return $this->example_property;
        };
    }

    public function get_example_property(){
        return $this->example_property; 
    }
}

$example = new ExampleClass();
echo $example->get_example_property();

Property $example_property must be false until you call it, then, the first time it is called, I want to assign 1 to it. What's wrong with my code?

Error: Error Object of class Closure could not be converted to string on line number 20.

Answer 1

I just tried to play a little bit with your code.

To make it possible, you'll have to find out, whether your variable is a function (defined in your __construct) or the number set by this function

<?php

class ExampleClass{

    private $example_property = false;

    public function __construct(){
        $this->example_property = function() {
            $this->example_property = 1;
            return $this->example_property;
        };
    }

    public function get_example_property(){
        $func = $this->example_property;
        if(is_object($func) && get_class($func)=='Closure'){
            return $func();
        }
        return $func;
    }
}

$example = new ExampleClass();
echo $example->get_example_property(); //returning 1
echo $example->get_example_property(); //returning 1 again

But anyway, I don't see any sense in doing this.

The typical solution would be something like this:

class ExampleClass{

    private $example_property = false;

    public function __construct(){
        //usually initializing properties goes here.
        //$this->example_property = 1;
    }

    public function get_example_property(){
        // I think you want a value to be initialzed only if needed.
        // so then it can go here.
        if(!$this->example_property) {
            $this->example_property = 1; //initialize it, if needed
        }
        return $this->example_property;
    }
}

$example = new ExampleClass();
echo $example->get_example_property(); //returning 1
echo $example->get_example_property(); //returning 1 again