[m-dev.] cc_multi or det ?

[Peter Schachte]

On Tue, Aug 07, 2001 at 01:59:16AM -0700, Ralph Becket wrote:
> I use error codes in places where I expect to have to recover from 
> errors and exceptions for more drastic situations where graceful 
> recovery is largely not an option.
> 
> Handling errors of the former kind with exceptions often makes my
> code less legible than the equivalent kind using error codes.

Can you give a simple example?  I find polluting the datatypes with error
wrappers, and the code with wrapping and unwrapping, makes code less legible.

> If I don't *have* to write error handling code on
> the first pass, I probably won't.

That's a *good* thing:  it lets you concentrate on the main concepts, and
deal with the fiddly error cases later.  I suppose you'll argue that that's
a bad thing because you might design yourself into a corner, and not be able
to get a sensible design when you need to code for the error cases.  I
haven't seen this; I guess that's what I'd like an example of.

>  Mercury style error codes don't give
> me this option: I have to deal with them when they arise.

Only if all your code is det.

> The other problem is that retrofitting error recovery code can be a
> major pain, particularly if there's some state you want to preserve
> from the point at which the error occurred.

Can't you just pass that state back in the exception term?


-- 
Peter Schachte                     In a democratic time culture, everyone's
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