byKey and byValue: properties or methods?

[Alvaro]

El 20/01/2012 18:58, Andrei Alexandrescu escribió:
> On 1/17/12 12:48 AM, Andrei Alexandrescu wrote:
>> I hate I must ask this:
>>
>> int[string] aa;
>> foreach (k; aa.byKey) { ... }
>>
>> or
>>
>> int[string] aa;
>> foreach (k; aa.byKey()) { ... }
>>

I vote properties.

The general rule to me the is a function represents an *action* and 
usually has a verb in its name while a property is logically something 
of an object and its name is basically a noun, but nothing is said about 
whether that thing is stored (a field). A function *does* something, a 
property *is* something. I'm using "is" in a special way maybe because 
property values might not actually exist and be created/computed on the fly.

"circle.area" is the area of a circle. Whether its value is stored or 
computed on the fly does not change that.

aa.byKey is a range of keys, so, property.

Even "a.dup" *is* "a duplicate of a" so it's OK as a property even if it 
is not a "part" of a. Emphasis on the action of creating that duplicate 
is removed.

BTW, someone said that properties bring something more to remember (is 
it a.b or a.b()?) but I think they actually reduce doubts:

How would I change the radius of a circle in another language? 
circle.setRadius(2), circle.SetRadius(2), circle.set_radius(2), 
circle.radius_set(2)? With properties "circle.radius=2;" easier to remember.

My two cents.