D Ranges

[H. S. Teoh]

On Fri, Sep 13, 2013 at 10:49:23PM -0400, Jonathan M Davis wrote:
> On Saturday, September 14, 2013 04:10:09 Jesse Phillips wrote:
> > Anyway, my recommendation isn't to build up a class structure
> > just because that is what you would do in another language.
> > Figure out if the usability provided by inheritance is what you
> > want, if not struct with helper functions seems to be simplest in
> > development and maintenance. Destroy.
> 
> I find that I use classes very rarely in D. Once in a while, I need
> polymorphism, and in that situation, I use classes, but at least in
> the types of programs that I've usually been writing, polymorphism has
> rarely made much sense. Structs deal with most everything just fine.
> 
> Classes definitely have their uses, but IMHO, they should not be the
> first tool to pull out of your toolbox when writing a D program. Just
> use them when you actually need them.
[...]

I've found myself hovering between structs and classes when writing D
code. I almost always use structs for ranges, just because value types
incur less overhead, which does add up when you use a lot of UFCS
chaining.

OTOH, I find myself switching to classes just to get the reference
semantics in other cases, even if I never actually do any inheritance.
Trying to do reference semantics with structs, while certainly possible,
is just too error-prone IME. Just a few days ago, I encountered what
looked like a nasty functionality bug in my program, only to eventually
discover that it was caused by a missing 'ref' in a function's struct
parameter, so updates to the struct didn't persist as the code assumed
it would. I found myself seriously considering using classes instead,
just for the default ref semantics.

While D's decision to make structs value-only and classes ref-only is
certainly clever, it also introduces some tricky gotchas for the unwary.


T

-- 
May you live all the days of your life. -- Jonathan Swift