const?? When and why? This is ugly!

[grauzone]

dsimcha wrote:
> == Quote from hasen (hasan.aljudy at gmail.com)'s article
>> I haven't been following D for over a year .. now I notice there's a const!!
>> In C++, in my experience, the only time I need const is when I pass
>> temporary objects by reference and the compiler refuses, so I make the
>> parameter const to make the compiler happy.
>> void my_func( const SomeType& obj ) { ... }
>> This is annoying because now const propagates like a virus! any function
>> that I call on `obj` must also be changed to accept a `const` reference.
>> any  method on obj which doesn't change it must also be marked as
>> `const` in order for it to be callable from inside this function.
>> This whole stupid process wouldn't even be needed in the first place if
>> C++ had a garbage collector, because then I would always "new" them (as
>> per Java, C#, and D)
>> SomeType *obj = new SomeType();
>> but because there's no garbage collector, I have to create the object
>> not as a reference.
>> SomeType obj();
>> Again, this is all stupid C++ stuff that shouldn't even be needed in the
>> first place.
>> However, with all that being said, that's just my opinion, maybe over
>> the time some people found some actually useful uses for const, great,
>> so they can use it if they want.
>> What really annoys me is the viral nature of const.
>> Yesterday I was reading this: http://www.digitalmars.com/d/2.0/const3.html
>> (btw, this page is empty: http://www.digitalmars.com/d/2.0/const.html )
>> and, to my surprise, I see:
>> char[] p = "world"; // error, cannot implicitly convert invariant
>> 		    // to mutable
>> and all I can think of is: WHAT - THE - HELL??!!!!!!
>> invariant(char)[] is ugly! might as well be saying std::vector<char>
>> (ok, not the best example of stupidity, but I hope you get my point).
>> (and, is invariant(char)[] the correct type? or must it be
>> invariant(char)[5]??)
>> This is not the D that I loved. What's going on?
>> P.S. look here
>> http://stackoverflow.com/questions/557011/d-programming-language-char-arrays/
>> I know you can use "auto" and all that, but still .. I don't feel good
>> about this.
> 
> Uhh, that's what aliases are for.  The string alias is defined automatically in
> object, and string is an alias for immutable(char)[].

That Phobos introduces this alias is not really an argument that speaks 
in favor of the syntax.

Also, I don't quite understand yet what constness is good for. While it 
seems to be a good idea, it seems to be more an annoyance in practice. 
It doesn't seem to pay off. What is this additional complexity for? And 
really, what was wrong with not having constness? All I hear is 
something about threading, but I didn't see anything convincing yet. No 
real examples, not even a full concept. Only some loose arguments. Come 
on, the newest compiler releases can do const, now convince me already 
that it's a good feature!

Regarding pure functions: isn't CTFE already enough?

> Also, modulo a few library functions that use strings/immutable(char)[]s, when
> they should be using const(char)[]s, one can avoid const by simply not using it if
> one doesn't like it or doesn't need it for the program they're writing.