Re: Disallowing Pre-Defined Operations

["Marin D. Condic" <mcondic-nospam@quadruscorp.com>]

Tarjei T. Jensen wrote:
> Why should it be slow??? All (at least most) of the action should be at the
> compile stage. That is when the checking is done. The generated code should run
> as usual.
> 
> All that happens is that there should be fewer run-time errors to discover
> since the universe describe all the legal operatons with the various datatypes.
> If you try to multiply velocities the compiler will tell you that it is not
> legal.
> 
Maybe you missed the point. The checks *must* be at runtime - similar to
Constraint_Error except that no exception gets raised. When the value
exceeds the range, the object is saturated to its max/min value. This is
inherently slow in that you can't just do the math, but have to check
results and saturate at every step of the way. (Unless the hardware has
direct support for it. I've not encountered that anywhere, but that
doesn't mean it doesn't exist.) Given that an application may perform
thousands - or millions - of math operations, adding the extra overhead
can get quite costly. In hard real time situations where saturated math
is quite a common desire, you often need to get the math done in
extremely small amounts of time. So you want code that is as totally
optimized as possible.

MDC

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