jerzy.karczmarczuk@info.unicaen.fr wrote:
This discussion is not about adding it, but about whether or not it should have a default. Are you suggesting pi should be removed from the Floating class? Then, what type would you give pi?
First, I don't care whether it is there or not. When I use it, I define a particular instance (double, a constant formal series, a constant element of some differential algebra I enjoy personally, etc. No default would help me anyway). And then, I give it the type it deserves.
Evidently you use pi in more 'serious' programs than I do. I use pi simply for geometric reasons, when I wish to specify circular or elliptic paths or similar constructions. For this I am pleased that the language libraries give me pi, because they save me the work of defining it.
Given that pi is often used with sin, as in "sin (t * pi)" it would seem very odd if pi forced that to be monomorphic:
Oh yes, everybody in the world uses in ONE program several overloaded versions of pi, of the sine function, etc. Well, perhaps not everybody, for example I don't. And I use numerics quite often.
I like to write a complex function which might use multiple trig functions and pi, to describe the kind of thing about. I might want to use that function at Double, or GLdouble, or GLfloat, for various reasons. I don't particularly want to have to think about that kind of thing more than I have to.
How often *you* needed simultaneously overloaded pi and trigs in such a way that a default could help you? Answer sincerely (if you wish to answer at all...)
The default wouldn't help me at all. The default would help a (putative) designer of a new Floating instance, and I have never been one of those. If it is true of many Floating instances that (atan 1 * 4) is an accurate way to calculate pi (and it appears to be 'accurate enough' for Float and Double, on my computer) then adding it as a default doesn't appear to do any harm. I can't say I think it's very important either. Jules