Most basic nothrow, pure, @safe functions?

[Steven Schveighoffer]

On Fri, 21 Mar 2014 14:18:05 -0400, Walter Bright  
<newshound2 at digitalmars.com> wrote:

> On 3/21/2014 12:59 AM, monarch_dodra wrote:
>> Ok. That's a fair point. So in that case, our function is pointing at  
>> "data",
>> and is allowed to mutate it, and observe its state.
>>
>> Now, if *another* piece of code is doing the same thing at the same time
>> (potentially mutating "data", does that still violate purity?
>
> A mutex essentially reads and writes a global flag, which other  
> functions can also read and write.
>
> That makes it NOT pure.

No, that's not the case. A mutex does not write a global flag, it writes a  
shared flag. And the flag is passed into it.

I still think straight locking and unlocking of mutexes should be pure,  
because of the exclusive nature of the data protected by them.

-Steve