LSP example: is it interpreted in the right way? about clean-code-javascript

[ryanmcdermott]

Great points, all around. I had trouble getting a Good example to be clearly good. I want to improve the Good case here, and I think we can while still keeping the essence of the example about shapes. Here are my thoughts:

I think we need to remove the switch case because that's clearly violating OCP. We want a function that renders large shapes, and it can take squares and rectangles. Maybe what we do is pull out the code for setting length vs. setting height and width, into the declarations part:

// Should we set the sides here?
const rectangles = [new Rectangle(), new Rectangle(), new Square()];
renderLargeRectangles(rectangles);

[alemarre]

In current "bad example" :
The sentence If Square is a subtype of Rectangle, then objects of type Rectangle may be replaced with objects of type Square is actually true.
Square class has setWidth and setHeight methods, that can be called transparently as if it was a Rectangle.

In current "good example", the same sentence is actually false, you have to check type to avoid calling a method not implemented.

Concerning the comment // BAD: Will return 25 for Square. Should be 20. : why it is bad ?
You are calling setWidth and setHeight methods in a row, which, for a Square, link logically to the same method, so obviously the last call take precedence.

I would just inverse the two examples.. and remove the comment BAD.. :)

[ryanmcdermott]

If either of you want to make a PR feel free 😄 I have an idea on how to refactor but would like others' input!

[ryanmcdermott]

Closed as per #182