Re: Compiling C++ modules

[James Courtier-Dutton]

Avi Kivity wrote:
> > The "advantages" of the former over the latter:
> >
> > (1)  Without exceptions (which are fragile in a kernel), the former 
> > can't return an error instead of initializing the Foo.
> Don't discount exceptions so fast. They're exactly what makes the code 
> clearer and more robust.
>
> A very large proportion of error handling consists of:
> - detect the error
> - undo local changes (freeing memory and unlocking spinlocks)
> - propagate the error
>
> Exceptions make that fully automatic. The kernel uses a mix of gotos 
> and alternate returns which bloat the code and are incredibly error 
> prone. See the recent 2.6.16.x for examples.
C++ exceptions are much more error prone than C. Well not exactly error 
prone, but more non-deterministic.
This is one of the reasons that Software standards allow C++ at lower 
levels, e.g. DAL E, but at higher levels, e.g. DAL B, C++ is not 
allowed, but C is.
So, one can conclude that a C program can be made more reliable than a 
C++ program. One aim of a kernel is reliability.

James
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