Uh... destructors?

[Steven Schveighoffer]

On Tue, 22 Feb 2011 15:48:42 -0500, %u <wfunction at hotmail.com> wrote:

>> D pure functions are significantly different than this definition
> (as of recent times, when weak-pure was added).
>> Essentially, a pure function cannot access global variables.
> However, it can access variables referred to via a member of the
> object instance.
>> i.e. this is a valid pure function:
> class C
> {
>    int x;
>    pure void foo() { x++; }
> }
>
> I... did not know that. But even in that case, pure wouldn't make much
> sense, because doing anything like freeing memory or closing a file
> handle affects global variables (whether directly in the runtime or
> indirectly in the OS)... right?

Freeing and allocating memory is fair game for pure functions.  It is one  
of the only exceptions to the rule, because without the ability to  
allocate and free memory, functional programming is quite limited.

On closing a file, you couldn't close that file unless the function to  
close it was marked pure.  I would *hope* that the C call to close a file  
was not marked as pure.

I wasn't advocating that destructors can be pure, I was just pointing out  
that the concept of pure has changed in recent times.

-Steve