Class call function

matthewo256

I'm just trying to illustrate my question here, so please don't nit-pick about the crude programming 😉

I've got a class that's creating new instances of other classes inside it. My question is, how do I call a function from the subclass in the main class?

class Form
{

function Form()
{
$subform = new SubForm();
}

function maxFieldSize()
{
return 47;
}
}

class SubForm
{
function SubForm()
{
$size = parent::maxFieldSize();
return "<input type=text size=".$size.">";
}
}

laserlight

matthewo256 wrote:
I've got a class that's creating new instances of other classes inside it. My question is, how do I call a function from the subclass in the main class?

The term "subclass" refers to a derived class, and from your use of the "parent::" prefix it appears that you think that SubForm is a derived class of Form. However, you did not actually use the extends keyword to make this so.

By the way, please post your well indented PHP code in [php][/php] bbcode tags.

matthewo256

OK, sweet. I fixed it with "class SubForm extends Form".

Now, how about this one? var_dump() shows all three variables, but I can't seem to call them directly.

abstract class FormInput
{
  private $_value = "value";
  private $_name = "name";
}

class FormLongText extends FormInput
{
  private $_var = "var";
  function showData()
  {
    echo $this->value;
    echo $this->name;
    var_dump($this);
  }
} 

$var = new FormLongText;
$var->showData();

laserlight

The derived class cannot access the variables from the base class because they are private. This is usually fine.

scrupul0us

$value and $name need to be 'protected' variables not 'private' for them to be accessible by the subclass

matthewo256

scrupul0us, that's perfect! Thanks!

laserlight

matthewo256 wrote:
scrupul0us, that's perfect! Thanks!

scrupul0us was stating a fact (but not very accurately: a public member variable will also be accessible to a subclass), but whether or not protected member variables are appropriate for the class that you are designing is another matter. Ideally, member variables should be private (but in reality what is ideal is not necessarily what is best for the given situation).