Object dependence in case of a GUI framework

Imagine you have a class called Widget. Now you create a object from Widget, and you would append it to the global Widget.

local wid = Widget()
wid:resize(10, 10)
-- #  wid:getSize() would return the witdth and the height of wid
-- #  imagine globalWidget would be the screen
globalWidget:addChild(wid)

Now, you want to reposition the widget. What do you think is better and/or more intuitive? Please give a reason (e. g. just more intuitive or an real advantage).

globalWidget:repositionChild(wid, 5, 5)
-- #  Or
wid:reposition(5, 5)

I am not sure, because the position of an object is an information that doesn't belongs to that (it doesn't defines the state of this object).

I think wid:reposition is better.

Windows10User, on 24 May 2018 - 06:55 PM said:

I think wid:reposition is better.

Okay, but can you tell me please why? Is it just more intuitive or has it an advantage?

It has reliance on less variables
Plus, it is better off to leave an object to modify it's own internals, in case they are changed

EveryOS, on 24 May 2018 - 07:14 PM said:

It has reliance on less variables
Plus, it is better off to leave an object to modify it's own internals, in case they are changed

It is a matter of perspective, because the parent object will hold the information for all pixels, to form the image. Or do you have another solution?

I'd tell the child to move. Otherwise, what happens if you have children of children? You'd have to figure out parents of parents.

In my experience with existing frameworks (eg. Qt), each "layer" of objects will have its own reposition-like method. That method shifts itself and all of its children.

Bomb Bloke, on 24 May 2018 - 11:16 PM said:

I'd tell the child to move. Otherwise, what happens if you have children of children? You'd have to figure out parents of parents.

Think this is a good reason, i didn't thought in that way. Thank you!

Also, what if you change the parent of the child? Sometimes it is possible to do so.

I'd actually make it configurable. Giving parents control over child positioning lets you do cool things like auto-arranging grids/lists, and HTML-like 'flow' layouts. Of course, sometimes you want to just say "put this here exactly" so that's why I'd not say either one is the best standalone solution.

But what if you're not making a layout manager? Then the other way is easier

What about a compromise: we do both

globalWidget:repositionChild(wid, 5, 5)

If I would implement the reposition function in the parent, I would do it like this:

globalWidget:getChild(wid):reposition(5, 5)

This would also fix the issue Bomb Bloke pointed out:

Bomb Bloke, on 24 May 2018 - 11:16 PM said:

I'd tell the child to move. Otherwise, what happens if you have children of children? You'd have to figure out parents of parents.

Jummit, on 25 May 2018 - 09:07 PM said:

If I would implement the reposition function in the parent, I would do it like this:

globalWidget:getChild(wid):reposition(5, 5)

Tbh that doesn't really make sense because wid already is the child which was appended so globalWidget:getChild(wid) should return wid(If it returns anything else it would be pretty strange) and if it returns wid that would be the same as:

wid:reposition(5, 5)

Luca_S, on 25 May 2018 - 10:53 PM said:

Jummit, on 25 May 2018 - 09:07 PM said:

If I would implement the reposition function in the parent, I would do it like this:

globalWidget:getChild(wid):reposition(5, 5)

Tbh that doesn't really make sense because wid already is the child which was appended so globalWidget:getChild(wid) should return wid(If it returns anything else it would be pretty strange) and if it returns wid that would be the same as:

wid:reposition(5, 5)

Oh, I did something wrong there. I meant it like this:

globalWidget.wid = widget(1, 1)
globalWidget.wid:reposition(5, 5)