[phobos] Removing std.stdio.File.popen()

[Sean Kelly]

Or it updates the read offset when the buffer is adjusted.

On Aug 18, 2010, at 4:38 AM, Lars Tandle Kyllingstad wrote:

> On Wed, 2010-08-18 at 04:44 -0500, Andrei Alexandrescu wrote:
>> On 08/18/2010 03:10 AM, Lars Tandle Kyllingstad wrote:
>>> On Tue, 2010-08-17 at 22:03 -0500, Andrei Alexandrescu wrote:
>>>> I understand that, and the motivation has been thoroughly explained in
>>>> the Unix lore. My question is, why define a separate type? Wouldn't
>>>> creating a file and calling setbuf(null, 0) suffice?
>>> 
>>> 
>>> Well, for one thing, I didn't know about setbuf() until just now. :)
>>> 
>>> I still think I prefer the UnbufferedFile solution, though.  setbuf()
>>> should be called before anything is read or written to the stream.  This
>>> means it will be up to the user to do so, and this is easily forgotten.
>>> Compare
>>> 
>>>         auto f = UnbufferedFile("myfile.txt");
>>>         ...
>>>         auto p = spawnProcess("myapp", f);
>>> 
>>> to
>>> 
>>>         auto f = File("myfile.txt");
>>>         setbuf(f.getFP(), null);      // DON'T FORGET THIS!
>>>         ...
>>>         auto p = spawnProcess("myapp", f);
>> 
>> spawnProcess could call setbuf itself and fail if that doesn't go through.
> 
> 
> On my computer, setvbuf() doesn't fail when you turn off the buffer
> after reading something.  In particular, the following program runs
> fine:
> 
>        import core.stdc.stdio, std.string;
> 
>        void main(string[] args)
>        {
>            auto file = fopen(toStringz(args[1]), "r");
> 
>            auto data = new char[10];
>            fread(data.ptr, 1, data.length, file);
> 
>            // This should fail, but doesn't:
>            assert (setvbuf(file, null, _IONBF, 0) == 0);
> 
>            fclose(file);
>        }
> 
> This means that it either silently ignores the request to turn off
> buffering, or it ditches a whole lot of data. :(
> 
> -Lars
> 
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