Re: "Must instantiate controlled types at library level." Why?

[James Kanze <kanze@gabi-soft.fr>]

Martin Krischik <krischik@users.sourceforge.net> writes:

|>  Hyman Rosen wrote:
|>  > Ludovic Brenta wrote:
|>  >> You are not being helpful to anyone with this comment. If you
|>  >> think I am ignorant, please explain why, or otherwise give me one
|>  >> good reason not to put your name in my kill file.

|>  > Oh, by all means put my name in your kill file!

|>  > But OK. You state that "The std::vector template class is not a
|>  > first-class citizen". I haven't a clue as to what that might mean

|>  Ruffly: First class is everything you can use without (in C/C++)
|>  "#include" or (in Ada) "with" or (in Java) "import".

So bool and complex are not first class in C, because you need to "turn
them on"?  I'm afraid I don't really understand this distinction.  (The
way most C++ intantiations implement this is extremely primitive.  But
there's nothing second class about it, in the context of the language.)

|>  vector <> is not a first class citizen because you need "#include
|>  <vector>"

And on many of the early C implementations I'used, float wasn't first
class, because you needed to link in a special library to get it?

|>  And, of corse, to copy the hole content of an other file into your
|>  own file is cheating.

It's certainly not the most robust or the most elegant way of getting
the job done, but I don't quite understand why "cheating"?  What makes
it less honest than anything else (as opposed to simply being a less
efficient way of getting the job done)?

|>  More precisely: First class are only keywords, predefined operators,
|>  predefined types, (in Ada ) attribute and perhaps pragmas.

More precisely: First class is what you like, and second class is
everything else.

Not much of an argument, really.

|>  Actually: Even "#include" isn't first class since it is part of a
|>  preprocessor.

|>  I am unsure if, in Ada, Integer is first class since there is an
|>  implicit "with Standart; use Standart;".

|>  The argument is that everything inside a language need to be
|>  implemented with first class citizen - they are the fondatation of
|>  everything else and design errors in this area have profound
|>  consequences.

And one of the basic premises of Stroustrup is that there should be as
little in the language as possible.  I don't necessarily agree with this
attitude; some things, like closure, can really only be done effectively
from within the language.  But just saying it is bad, or second class,
doesn't prove anything.

|>  Out of my 10 years+ experience with C/C++ I say that the following
|>  are my personal top 3 C/C++ design mistakes which lead to most of
|>  bugs I had to hunt down insted the compiler just finding them for
|>  me.

|>  1) #include instead of an proper import/with. 
|>  2) implicit type convertion. 
|>  3) arrays are pointers. 

Arrays aren't pointers.  There's just another implicit type conversion.

And you don't mention the declaration syntax, which is enough to drive
any sane man up the wall.

-- 
James Kanze
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