2008/6/18 Gwynne Raskind <[EMAIL PROTECTED]>: > On Jun 18, 2008, at 2:36 AM, Alexey Zakhlestin wrote: > >> 1) I am not sure that the current semantics of the "lexical" keyword is >>> great in all cases. Is the reason why you don't allow by-value binding so >>> that we don't have to manage more than one lambda instance per declaration? >>> >> by-reference binding is much closer to other languages symantics. I >> guess, that was the main reason Christian chose it. >> "by-value" may still exist, if people find, that they need it, but >> only in addition, please. >> >> lambda has to reflect changing state of context, to be truly useful >> > > In Lua, the language in which I've seen the most of closures and lambda, > lexical scoping is handled this way: > > someVariable1 = "asdf"; > someVariable2 = "jkl;"; > SomeFunction = function() > local someVariable2 = "1234"; > > print someVariable1.." "..someVariable2.."\n"; > end > print gettype(SomeFunction).."\n"; > SomeFunction(); > someVariable1 = "qwer"; > someVariable2 "0987"; > SomeFunction(); > > The resulting output of this code fragment would be: > function > asdf 1234 > qwer 1234 > > The Lua interpreter handles this by resolving variable references as > they're made; "someVariable1" is looked up in the closure's scope and not > found, so the interpreter steps out one scope and looks for it there, repeat > as necessary. Once found outside the closure's scope, something similar to > the proposed "lexical" keyword happens. Closures and lexical variables can > be nested this way, to the point where a single variable in a sixth-level > closure could still have been originally found in the global scope. > > I'm not sure this would work for PHP, I'm curious what others think. > > Of course, that fragment does a very poor job of showing off the extreme > flexibility of Lua with regards to functions and scoping, but hopefully it > illustrates the concept. > > -- Gwynne, Daughter of the Code > "This whole world is an asylum for the incurable." > > > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > > Is "nested scope" just the same as "namespace" in this regard?
-- ----- Richard Quadling Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731 "Standing on the shoulders of some very clever giants!"
