Re: I/O - exception handling

[Jeffrey Carter <spam@spam.com>]

Robert I. Eachus wrote:
> Randy Brukardt wrote:
> 
>> While I don't think any implementor would plan to raise an exception
>> from Is_Open, certainly the standard allows Use_Error or Device_Error
>> and of course Storage_Error and Program_Error (if there are elaboration
>> problems). In practice, I think it's safe to ignore that possibility.
> 
> Totally agree with respect to Is_Open. However, there are cases where 
> exceptions on Close are not only possible but likely in some situations. 
>  For example it is perfectly legal in Ada to close Standard_Output and 
> other standard files.  There was even an AI a while back making it clear 
> that it is legal to do so, and what it means if the implementation does 
> support it.  But implementations (notice, not compilers, this is a 
> target OS or environment issue) may not allow some files to be closed, 
> and you will get Use_Error.

The language lawyers have spoken. To summarize, if I understand 
correctly, if you're dealing with "normal" files (not a standard file or 
device), Is_Open won't raise an exception and Close will only raise an 
exception if the file isn't open.

-- 
Jeff Carter
"Hello! Smelly English K...niggets."
Monty Python & the Holy Grail