[Cuis] [Ann] Fix to Exceptions, New expression chain syntax and more!

[Frank Shearar]

On 11 September 2014 16:34, Juan Vuletich <juan at jvuletich.org> wrote:
> Hi Folks,
>
> I've just commited to https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev a
> bunch of updates and a new image.
>
> Biggest news is a fix to Exceptions. There was a serious bug: when there are
> nested handlers of the same exception, the wrong handler got run. See
> #testHandlerFromAction . This bug is common to Squeak and Pharo also. The
> fix was provided by Andrés Valloud.

Thanks very much, Andrés! (And Juan, of course!) I have turned the
changeset into an mcz and submitted it to Squeak's Inbox. It does
cause a regression in our test suite, but more importantly does fix
this long-outstanding bug!

> Besides, Andrés did an extension to the Smalltalk syntax, using '::' for
> expression chaining. See #chainExamplesDoubleColon . I think it can help us
> avoid many opening parenthesis at the start of an expression, and many
> nested brackets in complex Boolean conditions. If you want to see how those
> expressions are written without the chain operator to compare, in
> #chainExamplesDoubleColon click on (show...) / decompile.

This is a very neat extension, and one I'd like to use myself. I've
wanted it pretty much since I saw Vassili Bykov write about it:
http://blog.3plus4.org/2007/08/30/message-chains/

What I'd like even more than this though is having a compiler/parser
well factored enough that the end user could monkey around with the
syntax. We're a long way away from that not just because of how
Scanner/Parser/Compiler are written, but also simply because grammar
composition is Hard (see
http://tratt.net/laurie/blog/entries/parsing_the_solved_problem_that_isnt)

frank

> I also did tweaks to the compilation of #to:do: and #to:by:do: after a
> discussion in Pharo-dev, and to #vmParameterAt: after a discussion in
> Squeak-dev. And some minor tweaks here and there.
>
> Thanks Andrés for your great contributions!
>
> Cheers,
> Juan Vuletich
>
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