• pineapple (7/7) Oct 22 2015 I'd like to use fread and fwrite in place of File.rawRead and
• pineapple (2/2) Oct 22 2015 Answered my own question: Turns out File.getFP() does exactly
• =?UTF-8?Q?Ali_=c3=87ehreli?= (10/13) Oct 22 2015 Would you not create that buffer? :)
• pineapple (5/12) Oct 22 2015 Cool, I hadn't realized slices worked like that. Still, it was
• John Colvin (9/12) Oct 22 2015 D's arrays *are* just buffer locations and lengths with a few

pineapple <meapineapple gmail.com> writes:

I'd like to use fread and fwrite in place of File.rawRead and 
File.rawWrite which force the creation of an array where I'd 
rather specify a buffer location and length. I'd like to do this 
using a File object but the handle for the C stream is a private 
member and I can't find any way to access it. Is there a getter 
or something I missed, or else some way to pry private data like 
this out of a class?

pineapple <meapineapple gmail.com> writes:

Answered my own question: Turns out File.getFP() does exactly 
what I needed

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 10/22/2015 11:20 AM, pineapple wrote:
 I'd like to use fread and fwrite in place of File.rawRead and
 File.rawWrite which force the creation of an array where I'd rather
 specify a buffer location and length.

Would you not create that buffer? :)

If you already have a piece of memory, it is trivial to convert it to a 
slice in D:

   auto slice = existing_pointer[0 .. number_of_elements];

 
http://ddili.org/ders/d.en/pointers.html#ix_pointers.slice%20from%20pointer

The operation is not expensive because D slices are nothing but a 
pointer and length.

Ali

pineapple <meapineapple gmail.com> writes:

On Thursday, 22 October 2015 at 18:28:50 UTC, Ali Çehreli wrote:
 If you already have a piece of memory, it is trivial to convert 
 it to a slice in D:

   auto slice = existing_pointer[0 .. number_of_elements];


 http://ddili.org/ders/d.en/pointers.html#ix_pointers.slice%20from%20pointer

 The operation is not expensive because D slices are nothing but 
 a pointer and length.

 Ali

Cool, I hadn't realized slices worked like that. Still, it was 
more convenient to use fread and fwrite in this case. I had an 
pointer where I wanted to be able to read and write one byte at a 
time and fread/fwrite are familiar and comfortable options to me.

John Colvin <john.loughran.colvin gmail.com> writes:

On Thursday, 22 October 2015 at 18:20:07 UTC, pineapple wrote:
 I'd like to use fread and fwrite in place of File.rawRead and 
 File.rawWrite which force the creation of an array where I'd 
 rather specify a buffer location and length.

D's arrays *are* just buffer locations and lengths with a few 
extra properties, methods and operators.

T* ptrToBuffer = /* ... */;
size_t lengthOfBuffer = /* ... */;
T[] buffer = ptrToBuffer[0 .. lengthOfBuffer];
File f = /* ... */;
T[] filledPartOfBuffer = f.rawRead(buffer);

Note that at no point in the above is a new buffer allocated.