Re: [Boost-users] upcoming Switch library review Jan 5th - Jan 9th

From: dan marsden (danmarsden_at_[hidden])
Date: 2008-01-02 16:36:23

Stjepan Rajko wrote:
> If you are interested, please consider submitting a review of this
> library.  I will send more detailed instructions on what to include in
> the review on the 5th.

Can I jump the gun with with a few questions please?

Why is the fall through behaviour to throw an exception? This is not consistent with standard switch, possibly a motivation section is needed in the docs to explain this type of decision?

I'm not too clear with the documentation what the parameter 'n' can be? It is of type 'Int' which is described as being an Integer in the parameters section of the documentation. What does this mean, any built in integral type, can I switch on a std::string? What are the limitations? I got a bit lost here in the docs here, after admittedly only a quick read. Maybe just some clarification is required?

The parameter section does not specify the arities of the 2 function object parameters, I had to deduce them from the example. Why do these have to be function objects, and not just any callable type, including ordinary functions (using the Boost.ResultOf mechanism to sort out the return type)? I'm not sure how useful that would be for 'f', but for 'default_' a full blow function object seems a bit much typing, can't I just use a function. 

Also, why is 'default_' unary, the default in a standard switch statement does not access the switch parameter, and the example does not exploit this feature either. Why not just a nullary function? Again some motivation might be nice.

And finally, as the introduction mentions the efficiency of the standard switch statement, could the docs show some performance stats for the library code for comparison?

Cheers

Dan




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