Const sucks

[Walter Bright]

Derek Parnell wrote:
> Remind me again what the difference between 'const' and 'invariant'
> is.

'const' means a I can't change it (but someone else can, such as someone
in a different thread). 'invariant' means nuttin' can change it, not
no-how, not no-way.


> What do these below mean ...
> 
> const int (* p)

syntax error

> const int *(p)

syntax error

> const int (*) p

syntax error

Imagine if const were a template called Const, and we used that template
to form a new type that was const of the old type. We'd invoke it like:
	Const!(T) t;
Now, just s/Const!/const/, and the syntax should make sense.


>> o  tail const of a struct would have to be done by making the
>> struct a template:
>> 
>> struct S(T) { T member; } S!(int)   // tail mutable S!(const(int))
>> // tail const
> 
> But most structs contain multiple members, and usually of different
> types.

That's up to the struct designer.