Re: I need a little help - it's been a long time - with enumeration type and for use representation

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

On Fri, 13 Nov 2009 14:30:44 -0700, Jeffrey R. Carter wrote:

> Dmitry A. Kazakov wrote:
>> 
>> I do it differently. I have the pattern:
>> 
>> procedure Get (Text : String; Pointer : in out Integer; Value : out Type)
>> 
>> which I consistently deploy everywhere. Get takes a textual representation
>> of Type from Text at Pointer and advances Pointer to the first position
>> following it. The result is returned though Value.
>> 
>> However, yes, usually I use a plain type conversion:
>> 
>>    Get (Text, Pointer, Integer (Value));
>> 
>> rather than Type'Val (when I am too lazy to instantiate the generic
>> packages once again with Type)
> 
> I still don't see where you would use 'Val.

As I said in place of type conversion. If you have some bit pattern as a
number you can use either Val or type conversion:

   declare
      N : Integer;
   begin
      Get (Text, Pointer, N);
      Value := Type'Val (N);   --- or Value := Type (N)
      ...

Type'Val is probably semantically cleaner than conversion. Then there are
cases where conversion cannot be used, e.g. for formal discrete types in
generics. There you have to use 'Val instead of conversion, 'Suc instead of
+1 etc.

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