Reddit: why aren't people using D?

[Lutger]

Walter Bright wrote:

> Michiel Helvensteijn wrote:
>> That's just a few reasons right there. D's properties lack elegance and
>> they lack potential.
> 
> Let's start with:
> 
> 1. What is a property?

A property contains information describing some object, which may or may not 
be mutable. 
 
> 2. How is that different from, say, a pure function?

A pure function is a computation without side effects:
- does not have to relate to any one object
- a mutable counterpart may not make any sense
- it cannot have any side effects while that may make sense even for a 
getter (lazy load for example)
- it does not have to *describe* an object in the sense that a property does

The mechanism may be exactly the same, but a property gives a big hint to 
the programmer (and tools) as to what kind of thing you are dealing with.

Extremely dumb example, all very much the same going from less to more nice:

color(corvette, Color.Red);
assert(color(corvette) == Color.Red);

corvette.color(Color.Red);
assert(corvette.color() == Color.Red)

corvette.color = Color.Red;
assert(corvette.color == Color.Red);