on 2/5/07 8:26 AM, Rici Lake at lua@ricilake.net wrote:
The complex part of implementing smalltalk blocks is the correct
handling of ^ (return) inside a block. This could be macro-expanded
into call/cc, if you have call/cc (actually, only a very limited form
of call/cc is necessary), but I don't see any obvious way of doing
that in Lua without introducing a coroutine; furthermore, the
coroutine solution may fail unexpectedly because Lua coroutines
lack delimiters.
A useful bit of subtlety to be aware of.
Fundamentally, blocks are a great way to enable non-guru programmers to
implement control structure like entities, but without support for
non-local
return (or break for that matter), they won't really feel quite like
control
constructs and adding such support potentially leads to continue
capture
issues though those can be addressed by declaring that a function scope
closes the first time we exit from the function.
