Question

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In PHP, whats the difference between :: and -> ?

This a continuation from my previous question – however I think its unique enough to warrant a new question.

What is the difference between:

Message::listMessages(); 

and

$message->listMessages(); 

I’m creating a mini-cms and I want a system that displays errors in a uniform fashion.

Cheers,
Keiran

Answer 1

Static methods come handy when we want to share
information between objects of a class, or want to represent something
that’s related to the class itself, not any particular object.

The difference between the two is in the way they are invoked.
For example, Message::listmessages() is a static method and can be called like this:

$messages = Message::listmessages($args);

You do not need to first make an object of class Message, in order to use the above. Also, note that this should be used when you want to return a result on definite pre-configured variables, and is not based on properties of class Message

However, $message->listmessages() is an instance method and can be called like this:

$message = new Message();
$messages->$args = $args
$messages= $message->listmessages();

This is used for generic occassions when you want to call a function on runtime properties of class Message.