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Re: safe/unsafe mode




On Wed, 23 Nov 2005, Sebastian Egner wrote:

>Mike wrote:
>> From this, and several other messages in the SRFI 77 archives, I'm
>> getting the impression there's some misunderstanding here about the
>> nature of safe/unsafe mode, as alluded to in the document.
>
>Always possible. I understand safe/unsafe mode to mean that there is
>some form of global switch (either compile-time or run-time) that is
>controlling whether certain arithmetic operations raise an exception
>when an error condition happens---or just press on. I understand that
>the 'unsafe' mode allows a compiler to produce code without range
>checking or tag-bit removal, with all sorts of performance benefits. Is
>this what you mean by safe/unsafe mode?

Actually, I think all he said was that it controls whether error
checking is required or optional - making all the "is an error"
language relating to exact/inexact arithmetic read as "an error is
signalled" when safe mode is on, and leaving it as is (and signalling
at the discretion of the implementation) when it's off.

You envision a different kind of control, where it's possible to
specify that errors should *not* be detected or signalled, and I
don't think that's what this says.

				Bear