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From: Peter Dimov (pdimov_at_[hidden])
Date: 2001-03-19 12:07:54

From: "Greg Colvin" <gcolvin_at_[hidden]>

> > I agree that an exception is not appropriate. I'm arguing that (1)
> > undocumented "assert" uses are bad, and (2) the proper way to document
> > "assert" is by using the term "undefined behavior."
> So the documentation is this? "If there is an error in my code,
> or the compiler that compiled it, or the system code that it depends
> on, or the hardware that the system code depends on, or any other
> unforseen circumstance, then undefined behavior might occur. Use at
> your own risk."


When the code does not work like the documentation says it will work,
including any documented "undefined behavior" cases, then it has a bug.

I say that we should separate error reporting from bug reporting. It may not
be appropriate to use the same mechanism for both.

In other words:

Error class #1: the programmer that wrote the application (that calls the
library) has a bug in his/her code.

Library Action: (documented) undefined behavior.

Error class #2: a runtime error occurred in the library that the application
programmer should handle.

Library Action: (documented) throw an exception.

Error class #3: the library, or the compiler, or the OS has a bug that can
be detected. Depending on the situation, the bug may or may not prevent the
library from functioning properly.

Library Action: (undocumented) report the error via the appropriate

My point is that a plain assert is fine for #1, but may or may not be the
best choice for #3.

Peter Dimov
Multi Media Ltd.

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