php - Evaluate object to a boolean

Question

Consider the following:

class MyClass
{
  private $var1 = "apple";
  private $var2 = "orange";
}

$obj = new MyClass();

if($obj) { 
  // do this
}
else {
  // do that
}

PHP evaluates my object to true because it has member variables. Can this logic be overridden somehow? In other words, can I have control over what an object of my class will evaluate to when treated as a boolean?

Answer 1

PHP evaluates my object to true because it has member variables.

This is incorrect. PHP actually evaluates $obj as true because it holds an object. It has nothing to do with the contents of the object. You can verify this by removing the members from your class definition, it won't make any difference in which branch of the if/else is chosen.

There is no way of making PHP evaluate a variable as false if it holds a reference to an object. You'd have to assign something "falsy" to the variable, which includes the following values:

null
array()
""
false
0

See the Converting to boolean from the PHP documentation for a list of all values that are treated as false when converted to a boolean.