switch()

Manu turkeyman at gmail.com
Thu Feb 20 18:51:49 PST 2014


On 21 February 2014 03:27, Ary Borenszweig <ary at esperanto.org.ar> wrote:

> On 2/20/14, 1:53 PM, Manu wrote:
>
>> On 21 February 2014 01:20, Steven Schveighoffer <schveiguy at yahoo.com
>> <mailto:schveiguy at yahoo.com>> wrote:
>>
>>     On Thu, 20 Feb 2014 10:13:27 -0500, Daniel Murphy
>>     <yebbliesnospam at gmail.com <mailto:yebbliesnospam at gmail.com>> wrote:
>>
>>         "Steven Schveighoffer"  wrote in message
>>         news:op.xbk44onleav7ka at __stevens-macbook-pro.local...
>>
>>
>>             What I really would be curious about is if in most D code,
>>             you see a lot more default: break; than default: assert(0);
>>
>>
>>         I just did a quick git-grep on the compiler source (not D, but
>>         all switches do have a default thanks to the d port)
>>
>>         With 707 "default:"s 68 had a break on either the same or next
>>         line, and 249 had an assert(0).
>>
>>         On phobos I get 22 assert(0)s vs 10 breaks with 147 defaults
>>
>>         With druntime i get 24 assert(0)s + 5 error();s vs 11 breaks
>>         with 64 defaults.
>>
>>
>>     Good data, but I was more thinking of people who use D, not the core
>>     language. The core language's developers have different behaviors
>>     than standard users. I'm not dismissing this data, but I would like
>>     to see more application statistics.
>>
>>
>> In my little app:
>>   17 default: break;
>>   1 default: assert(0); ... and I just realised it should have been a
>> final switch() anyway... so now there's 0.
>>
>
> Did you put those "default: break;" because:
>
> 1. The compiler told it to do so.
> 2. You already know the compiler will tell you, so you put it before that
> happens.
>

Because the compiler told me. It's not a habit of mine to type it.


In the cases where it was "1.", did it make you think whether you needed to
> handle the default case?
>

Never. If I meant to handle the case, I would have already handled the
case. I've never forgotten to handle the case when I was supposed to.
In the same way I've never forgotten to write else after an if when I
intend to.
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