In the "old" days, programmers made sure to respect the following conventions : you implement #storeOn:, #displayString: and #printOn: . Eventually, an object will be sent #storeString and #printString and will use your #whateverOn: implementation.

It looks like that good habit that I've learned at university looooooong ago got lost somewhere. It looks like no one uses #displayString anymore and rely solely on #printString instead! I had a teacher once telling me #displayString had a crappy implementation : it just sent #printString and that to be "code clean", one should implement #displayOn: and modify #displayString accordingly.

But if I recall, VW at the time introduced #displayOn: for widgets and other things, hence why #displayString never sent #displayOn:.

To make a long story short of what should have been and what it's always been, here's an excellent paper on the subject!

http://esug.org/data/HistoricalDocuments/TheSmalltalkReport/ST07/04wo.pdf

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Beno��t St-Jean
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On Tuesday, April 10, 2018, 11:28:57 a.m. EDT, Esteban A. Maringolo <emaringolo@gmail.com> wrote:

Isn't #displayString implemented in terms of #displayOn: the same way
#printString is implemented in terms of "printOn:"?

And in the case of String #displayString should return the receiver (it
is, self), so the following should be true.

| s |
s := 'Hello, ''Funny'' World'.
s displayString = s. "true"
s printString = s. "false"

Regards,

On 10/04/2018 12:21, Denis Kudriashov wrote:
> Hi.
>
> According to the comment of #displayString it should be used as default
> textual representation of objects in the UI:
>
> "While printString is about to give a detailled information about an
> object, displayString is a message that should return a short
> string-based representation to be used by list and related UI
> frameworks. By default, simply return printString."
> "asString should not be implemented in Object, and kept for
> conversion between strings, symbols, text and characters."
>
> But String itself does not respect this message:
>
> 'some string' displayString " ==> '''someString''' "
>
>
> Is it bug? Or is there any reason for this?
>
> Best regards,
> Denis

--
Esteban A. Maringolo