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| From: | Alex Sandro Queiroz e Silva |
| Subject: | Re: [Chicken-users] Re: tcp-read-timeout: procedure or parameter? |
| Date: | Wed, 25 Jun 2008 11:47:18 -0300 |
| User-agent: | Thunderbird 2.0.0.14 (Windows/20080421) |
Hallo, William Xu wrote:
Alex Sandro Queiroz e Silva <address@hidden> writes:<body> may call procedures that have a tcp-read-timeout free variable, but due to lexical scope that variable will most certainly not be bound to the one you want. For this you need dynamic scope.Do you mean something like the procedure `foo' call here?(define radix (make-parameter 10))(define (foo)(radix))(parameterize((radix 8)) (foo)) But the (foo) call is still bounded by (radix 8), hence the result isstill 8 ?
In this case foo sees the right radix variable, which is bound to a parameter, due to lexical scoping. But inside the parameterize block, that very same parameter will return a different value, acting like a dynamically bound variable.
-alex http://www.ventonegro.org/
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