[Pharo-users] Re: Please explain self

Objects are instances of a class. Classes are objects, so they have methods. 'self class' returns the class of self. If a class doesn't have a methods ... ... the search continues in the superclass. (every class has a superclass ... apart from Object). If you download the Blue Book  - "Smalltalk-80 - The language and it's implementation", it's free on the net, you'll find an AWSOME explanation and diagram from page 270 on, until ... ... the final map : classes and metaclass. but you've to read it these pages, before. There's a 'metaclass' concept to acquire. Bon voyage !     Davide On 12/12/2020 20:20, g_patrickb--- via Pharo-users wrote:

I understand if you have Class A with methods p and q that you can call q from p doing:

self q

But there are some cases where a method doesn’t exist but self is still used. I found a tutorial on creating a Reddit type app and it had a .mcz which I loaded.

Here is an example from Class StLoggedInComponent and method refreshReport:

self report rows: (self session user tasks select: self filterBlock).

There is a method ‘report’ so I understand that, but there is no method named ‘session’ so what is the use of self?

And Class StDatabase has method ‘updateTask:’ has:

self subclassResponsibility.

But no method called ‘subclassResponsibility’ exists in the Class.

Also, Class StLoggedInComponents has method ‘testTasks’ with this:

^ self class testTasks

What is ‘self class’?

Thank you.

-- Ing. Davide Grandi linkedin : http://linkedin.com/in/davidegrandi