Author: Sune Fischer
Date: 14:47:02 05/29/04
Go up one level in this thread
On May 29, 2004 at 11:33:01, James Swafford wrote:
>>
>>How would you pass arguments to a function in an unevaluated state? Can you draw
>>a stack frame showing exactly what would be done?
>
>The problem (well, Uri's problem) is the order in which the compiler
>evaluates the expression tree. Think of 'printf' as a node in a tree
>with the parameters as children.
>
>Apparently the children are evaluated first (bottom up), and since
>they share memory, voila...
>
>I think printf could do something like:
>
>While (unevaluated parameter) {
> evaluate parameter
> copy results to buffer
>}
>print buffer
>
>Not as efficient, but it would work.
>
>Note I am _not_ saying it _should_ work this way!
From what I understand the problem is not with printf, but in the way parameters
are passed to functions in general.
Eg. if I write F(3*x+4,0.6*y-2), then the program will first evaluate the
argumens and _then_ pass them to the function, F.
It is not possible for the compiler to replace that with two calls like F(3*x+4)
and F(0.6*y-2), because the compiler can't possibly know if F can handle that.
Printf is no exception I think, it gets treated like any other function in this
respect.
-S.
>--
>James
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