const?? When and why? This is ugly!

[Andrei Alexandrescu]

Walter Bright wrote:
> Andrei Alexandrescu wrote:
>> Walter Bright wrote:
>>> If I may restate your case, it is that given function that does 
>>> something with character arrays:
>>>
>>> int foo(string s);
>>>
>>> and you wish to pass a mutable character array to it. If foo was 
>>> declared as:
>>>
>>> int foo(const(char)[] s);
>>>
>>> then it would just work. So why is it declared immutable(char)[] when 
>>> that isn't actually necessary?
>>>
>>> The answer is to encourage the use of immutable strings. I believe 
>>> the future of programming will tend towards ever more use of 
>>> immutable data, as immutable data:
>>>
>>> 1. is implicitly sharable between threads
>>
>> In fact const data is also implicitly sharable between threads.
> 
> No. You have to declare it "shared const" to make it sharable between 
> threads.

Sorry, I got confused. What I meant was that a function accepting a 
const T can count on other threads leaving T alone, which is the 
converse of what you say. Cool!

Andrei