reading from a pipe

reading from a pipe

[milouz]

Hi,

I'd like to know how to read some bytes from a pipe or some other non-regular file such as device. I had a look at streams_io, direct_io, etc. but was not able to code something working.

How do we do that in Ada ?

Re: reading from a pipe

[Eryndlia Mavourneen]

On Wednesday, February 27, 2013 11:36:32 AM UTC-6, milouz wrote:
> Hi,
> 
> 
> 
> I'd like to know how to read some bytes from a pipe or some other non-regular file such as device. I had a look at streams_io, direct_io, etc. but was not able to code something working.
> 
> 
> 
> How do we do that in Ada ?

The following is a partial solution to the question, but gives the general idea:

-------------------------------

   with Ada.Text_IO, Ada.Text_IO.Text_Streams;
   use  Ada.Text_IO, Ada.Text_IO.Text_Streams;
   procedure Write_It is
      type My_Record_Type is ...;
      The_Record : My_Record_Type;
      Cmd_Stream : Text_Streams.Stream_Access := Stream (Standard_Output);
   begin
      My_Record_Type'Write (Cmd_Stream, The_Record);
   end Write_It;

--------------------------------

   with Ada.Text_IO, Ada.Text_IO.Text_Streams;
   use  Ada.Text_IO, Ada.Text_IO.Text_Streams;
   procedure Read_It is
      type My_Record_Type is ...;
      The_Record : My_Record_Type;
      Cmd_Stream : Text_Streams.Stream_Access := Stream (Standard_Input);
   begin
      My_Record_Type'Read (Cmd_Stream, The_Record);
   end Read_It;

--------------------------------

Build as two processes and invoke within .exe directory as:

   $ ./write_it | ./read_it

--------------------------------

  -- Eryndlia

Re: reading from a pipe

[Dmitry A. Kazakov]

On Wed, 27 Feb 2013 09:36:32 -0800 (PST), milouz wrote:

> I'd like to know how to read some bytes from a pipe or some other
> non-regular file such as device. I had a look at streams_io, direct_io,
> etc. but was not able to code something working.
> 
> How do we do that in Ada ?

There is no Ada way of doing that, because such operations are OS-specific.

Otherwise, you use the services provided by the OS at hand. E.g. under
Windows you call CreateFile, then do ReadFile. These are provided by
Win32Ada bindings.

There are also some libraries available that provide some layer of OS
abstraction, e.g. Glib. For these there exist Ada bindings as well.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de

Re: reading from a pipe

[ytomino]

On Thursday, February 28, 2013 2:36:32 AM UTC+9, milouz wrote:
> Hi,
> 
> 
> 
> I'd like to know how to read some bytes from a pipe or some other non-regular file such as device. I had a look at streams_io, direct_io, etc. but was not able to code something working.
> 
> 
> 
> How do we do that in Ada ?

Use Florist.
See http://en.wikibooks.org/wiki/Ada_Programming/Platform/POSIX

Re: reading from a pipe

[milouz]

> Use Florist.
> 
> See http://en.wikibooks.org/wiki/Ada_Programming/Platform/POSIX

It looks great. Thanks !