Streaming transport interfaces: input

[Dmitry Olshansky]

  On 14.10.2010 22:14, Steven Schveighoffer wrote:
> On Thu, 14 Oct 2010 13:39:03 -0400, Andrei Alexandrescu 
> <SeeWebsiteForEmail at erdani.org> wrote:
>
>> On 10/14/10 12:27 CDT, Steven Schveighoffer wrote:
>>> On Thu, 14 Oct 2010 11:34:12 -0400, Andrei Alexandrescu
>>> <SeeWebsiteForEmail at erdani.org> wrote:
>>> Please, use the term "seek", and allow an anchor. Every OS allows this,
>>> it makes no sense not to provide it.
>>
>> I've always thought that's a crappy appendix. Every OS that ever 
>> allows seek/tell with anchors allows ALL anchors, and always allows 
>> either both or none of seek and tell. So I decided to cut through the 
>> crap and simplify. You want to seek 100 bytes from here, you write 
>> stream.position = stream.position + 100.
>
> Um.. yuck.   We need to use two system calls to seek 100 bytes?
>
>>
>> Oh, that reminds me I need to provide length as a property as well. 
>> This would save us crap like seek(0, SEEK_END); ftell() to figure out 
>> the length of a file.
>
> So now you need to do stream.position = stream.length to seek to the 
> end of the file instead of stream.seek(0, Anchor.END)?  Plus, how will 
> you implement length, probably like this:
>
> auto curpos = seek(0, SEEK_CUR);
> auto len = seek(0, SEEK_END);
> seek(curpos, SEEK_BEG);
> return len;
Actually C Run-time library provides something very limited from the 
point of most native OS I/O functions,
at very least, Windows and Posix have a separate function for 
determining file length.
[snip]
>
> -Steve


-- 
Dmitry Olshansky