Call site 'ref'

Mehrdad wfunction at hotmail.com
Sun Jan 15 10:34:49 PST 2012


On 1/15/2012 5:36 AM, Alex Rønne Petersen wrote:
> Hi,
>
> I don't know how many times I've made the mistake of passing a local 
> variable to a function which takes a 'ref' parameter. Suddenly, local 
> variables/fields are just mutating out of nowhere, because it's not at 
> all obvious that a function you're calling is taking a 'ref' 
> parameter. This is particularly true for std.utf.decode().
>
> Yes, I realize I could look at the function declaration. Yes, I could 
> read the docs too. But that doesn't prevent me from forgetting that a 
> function takes a 'ref' parameter, and then doing the mistake again. 
> The damage is done, and the time is wasted.
>
> I think D should allow 'ref' on call sites to prevent these mistakes. 
> For example:
>
> string str = ...;
> size_t pos;
> auto chr = std.utf.decode(str, ref pos);
>
> Now it's much more obvious that the parameter is passed by reference 
> and is going to be mutated.
>
> Ideally, this would not be optional, but rather *required*, but I 
> realize that such a change would break a *lot* of code, so that's 
> probably not a good idea.
>
> Thoughts?
>
I suggested this a while ago but people acted as though I was talking 
about aliens...


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