Array>>#at:put: should return the stored value

[smarr]

This is currently inconsistent between different SOM implementations.

The following program should result in the same output for all SOMs:

arr := Array new: 4.
(arr at: 1 put: 43) println.

Current behavior:

• SOM (java): instance of Array
• TruffleSOM: 43
• yksom: something line instance of Array looking at https://github.com/softdevteam/yksom/blob/68df0e2f2193d1e442bace3d62b969ed1789853a/src/lib/vm/core.rs#L742
• JsSOM: 43

There's also an assumption in #25 that Array>>#at:put: returns the value just stored.

/cc @ltratt

[ltratt]

Which of those is the preferred / intended semantics?

[smarr]

Returning the just stored value seems the most useful semantics to me.
My guess is that the returning of the receiver was implemented in the original SOM, because it requires fewer stack operations. Not something that seems particularly useful.

[ltratt]

I have no strong opinions here, but returning the array does allow you to chain put's and the like.

[smarr]

@krono @fniephaus I checked on SqueakJS, and Squeak returns the value instead of the array.
From your perspective, would there be a reason to deviate from it?
Well, I guess in Squeak the question isn't really one because it got message cascades.

[fniephaus]

Here's what ArrayedCollection class>>#with:with:with:with:with:with: looks like in Squeak:

with: firstObject with: secondObject with: thirdObject with: fourthObject with: fifthObject with: sixthObject
	"Answer a new instance of me, containing only the 6 arguments as elements."

	| newCollection |
	newCollection := self new: 6.
	newCollection at: 1 put: firstObject.
	newCollection at: 2 put: secondObject.
	newCollection at: 3 put: thirdObject.
	newCollection at: 4 put: fourthObject.
	newCollection at: 5 put: fifthObject.
	newCollection at: 6 put: sixthObject.
	^ newCollection

That could of course be rewritten using a cascade. If at:put: returned self, I'd still prefer a cascade over nested brackets:

(Array new: 2)
 at: 1 put: true;
 at: 2 put: false;
 yourself

vs.

((Array new: 2) at: 1 put: true) at: 2 put: false