On 11. 9. 2019 3:23, Richard O'Keefe wrote:
It is good that you have a coherent idea of how << can work.
After the changes sent by Sven, Pharo 8 seems to have the exactly same idea. IMNSHO.
The question I was addressing is how << *DOES* work in Pharo. Having simple things working, if they are kept consistent, is indeed good. The problem is that in Pharo 7 they are NOT consistent, and << does NOT work consistently, because there are occasions when << does ^something nextPutAll: something else and nextPutAll: returns something else.
Bug. '^' should not have been there.
I am grateful for the link to the changes to Pharo 8. That's a massive simplification and improvement. There is some way to go yet.
Actually, from my PoV, just the fix I posted. The rest seems correct.
The very first thing that should be done is to write down what the *semantics* of #<< is supposed to be, and then to ensure it is implemented that way. > Let's look at the chunk example.
exportTraitDefinitionOf: aClass on: aStream  "Chunk format."  aStream    nextPutAll: 'Trait named: '; nextPutAll: aClass name; cr;
The devil is in the details. Why you changed `printSymbol: aClass name` for `nextPutAll: aClass name`? Now it outputs things incorrectly. You should have changed it for `print: aClass name asSymbol` And this is precisely that distinction between low-level nextPutAll: and high-level write: / << / print:.
   tab; nextPutAll: 'package: '; print: aClass category; nextPutAll: '!!'; cr.  aClass comment isEmpty ifFalse: [    aStream      nextPutAll: '!!'; print: aClass; nextPutAll: 'commentStamp!!'; cr;      nextPutAll: aClass category withDelimiter: $!; nextPutAll: '!!'; cr].  aStream cr.
With the exception of #nextPutAll:withDelimiter:, this is completely standard and portable. If I am willing to do something nonstandard,
 aStream format: 'Trait named: {s}{n}{t}package: {p}{n}'    with: aClass name with: aClass category.  aClass comment isEmpty ifFalse: [    aStream format: '!!{p} commentStamp!!{n}{D$!}!!{n}'      with: aClass with: aClass comment].  aClass format: '{n}.
#write: really does not seem to be any improvement over #nextPutAll:.
Will post.
For what it's worth, GNU Smalltalk also has #<<, which it defines to be equivalent to #displayOn:, if memory serves me correctly. It has never been clear to me what the use case for #write: is. In Pharo 7, for streams it is the same as #putOn: except for the result. Neither of them is in any interesting way "higher level" than #nextPut: or #nextPutAll:, merely less informative.