Re: quiz for Sequential_IO Read

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2017-09-03 14:43, Frank Buss wrote:
> On 09/03/2017 02:26 PM, Dmitry A. Kazakov wrote:
>> On 2017-09-03 13:01, Frank Buss wrote:
>>> What does this program output?
>>
>> Garbage.
>>
>>> with Ada.Sequential_IO;
>>> with Ada.Text_IO; use Ada.Text_IO;
>>>
>>> procedure Hello is
>>>
>>>     type Byte is range 0..255;
>>>
>>>     package Byte_IO is new Ada.Sequential_IO(Byte);
>>
>> Ada.Streams.Stream_IO is for the purpose.
>>
>> (Sequential_IO is practically never used)
> 
> I started learning Ada today,

Great!

> where can I read about good coding 
> practice, and how would the example look like with Stream_IO, and maybe 
> even a correct version?
> 
> I read about Sequential_IO in the Ada Programming wikibook, where it is 
> recommended for homogeneous binary data:
> 
> https://en.wikibooks.org/wiki/Ada_Programming/Input_Output

Well, Sequential_IO is not recommended because:

1. It would make your program non-portable;
2. It would hinder interoperability with programs written on other 
languages;
3. It requires homogeneous data, which is never the case in real life
4. It limits I/O to files

In practice Stream I/O is a better choice. You also should not use 
compiler-generated serialization attributes (see T'Read, T'Write, 
T'Input, T'Output attributes). These are not portable either. You should 
always replace them with your own.

P.S. Sequential_IO was introduced in Ada 83. A lot of things changed 
since then.

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