Re: Introductory Ada Programming Book

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 17-01-04 15:44 , raph.amiard@gmail.com wrote:
> I'm in contact with the author so I'll pass any fixes up to him if you don't mind
>
>>   exit when (a == 0)
>
>> Switch statements must cover all possible input values --- for unbounded
>> types like integers, a when others is mandatory.
>
> I imagine you refer to the use of "unbounded" when refering to the integer type ?

That term is one nit that could be picked, but more specifically, it is 
quite possible to write "case" statements using an integer type without 
an "others" clause. Very recently, I had occasion to write code like this:

    X : Int_Type := ...
    ...
    case X is
    when Int_Type_T'First .. -1 => ...;
    when 0                      => ...;
    when 1 .. Int_Type'Last     => ...;
    end case;

>> Oddly, variables are not initialised by default
>> (Personal opinion: default initialization is a huge mistake)
>
> Ok but, besides the "oddly" qualifier, his statement is correct, right ?

Except for variables of an access type, or (but perhaps this is not "by 
default" in his view) of a record type where the components are given 
initial default values.

Requiring default initialisation of all variables, even unused ones, 
would have a large cost in execution time of any subprogram that uses a 
local array variable as a buffer for some data. In a 
resource-constrained real-time application that could be nasty. (For 
such code, I have once or twice argued with PA/QA people who see a 
coding rule that says "all variables must be initilised before use" and 
who think that "X := value" is a "use" of X :-) ).

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .