switch()

[Timon Gehr]

On 02/17/2014 04:59 AM, Manu wrote:
> On 17 February 2014 03:14, Timon Gehr <timon.gehr at gmx.ch
> ...
>
>     Of course, I'd just write the above as:
>
>     int difficulty = e.note.note.between(60,108) ? (e.note.note-60)/12 : -1;
>
>
> Yes yes, very clever.

I can't agree.

> Obviously it's an example and could come in any shape or form.

Obviously. Hence, no need to point this out.

> Personally, I also wouldn't do that anyway; basic readability has
> definitely been lost.
> ...

IMO quite the opposite is true. And everything around it will tend to 
become simpler to follow at a glance as well.

>
>         The default case is a total waste, since -1 should just be
>         assigned when
>         initialising the variable above.
>         ...
>
>
>     How is the compiler supposed to know? It might be a logic error for
>     e.note.note to be out of range.
>
>
> Then I should have used an invariant or something actually designed for
> catching values out of range.
> It's not the compilers fault I made a logic error. I could make a logic
> error literally anywhere in my code. Why force an annoying rule

It's not inherent to the rule.

> to maybe sometimes catch exactly one case

Well, it is also not the kind of error I make, but it still documents 
intention. It would be easy to sloppily omit default: assert(0) without 
this rule without actually affecting correct code, but I wouldn't warmly 
recommend this practice.

> (while making other competing cases where a logic error isn't present more annoying).
>

That's roughly the dynamic typing argument. Obviously 'switch' is quite 
lame (being lame seems to be an inherent quality of statement-based 
syntax), but the requirement to explicitly handle the default case 
instead of implicitly skipping it is not why.