Re: some trivial questions?

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

On 08/11/2017 23:49, Robert A Duff wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>>> I'd also prefer that function results and 'out' parameters
>>> have identical semantics, which they don't in Ada.
>>
>> Yes, but there are syntax problems with that:
>>
>>     procedure Generate_Two_Strings (X, Y : out String);
>>
>> How do I declare
>>
>>     X, Y : constant String := Generate_Two_Strings;
> 
> Something like:
> 
>      X, Y : constant String;
>      Generate_Two_Strings (X, Y);
> 
> could be made to work.  But that's nothing like Ada.

Nothing like a good language at all.

>> How do I do
>>
>>     2 x Ada.Text_IO.Put_Line (Generate_Two_Strings);
> 
> Store them in constants, I guess.

That defeats the purpose and what about objects with loaded semantics, 
like controlled helper types (references etc). It is not a good idea to 
produce named copies of in whatever form.

[ Passing arguments to subprograms is a directed graph. With only one 
child per node it is simple to write the graph down in a bracketed form. 
Without that it becomes kind of weird. ]

>> BTW, there is no reason why "with" should not be nested. If a unit can
>> depend or not on a unit so a block can. One could even invent some
>> interesting elaboration rules for nested "with"s. (:-)) And in effect
>> nested "with" do exist for separate bodies.
> 
> The rules about subunits are just plain weird.  They confuse the
> issues of visibility/dependence and separate compilation.

or maybe reflect the reality?

>>> I think nested packages and child packages should have identical
>>> semantics (so "with" should apply to both).  That was probably
>>> impossible, because child packages were invented too late.
>>
>> Yes. E.g. what if nested package instantiation would not imply "with"?
>> Should the similar [flawed] logic apply here as to "use"?
> 
> I don't understand those questions.

    package Foo is new Bar;
    use Foo; -- That must be illegal

Now the "right" way:

    package Foo is new Bar;
    with Foo; -- For the sake of "showing dependencies"
    use Foo;  -- That's right!

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