On Fri, 24 Jul 2009 14:10:59 -0400, Walter Bright
<[email protected]> wrote:
Steven Schveighoffer wrote:
I don't think properties should be necessarily pure anyways. How do
you have a pure setter? It's more of a convention that a property
getter should not change the state of the containing entity, a pretty
much non-enforcable convention.
That's my problem with properties as a distinct syntax - they don't have
distinct uses or behaviors.
If you delineate what can be called how, then you elminate syntax
ambiguities from occurring, and eliminate bizarro cases of syntax. The
difficulty is that the "human meaning" of a property is different than the
human meaning of a function. To the compiler, they're all functions, so
you as the compiler writer aren't seeing that they are different. I think
we all agree that writefln = "hi"; makes absolutely no sense to a person.
But it makes complete sense to the compiler, because it has no idea what
the word "writefln" means to a person.
It's the exact same reason + is not the concatenation operator.
Semantically, making + concatenate two strings together would be
completely unambiguous from adding two integers together because strings
do not define addition, and integers do not define concatenation. From
your own documentation, someone seeing "10" + 3 might think that he would
get 13 or "103". Even if the compiler defines what "should" happen, and
the rules are unambiguous, it looks incorrect to the user.
But having ~ be the concatenation operator makes it completely unambiguous
what the syntax means, regardless of what the types are. So the compiler
and the user are talking the same language, and the user isn't freaked out
by the "human meaning" of the syntax.
-Steve
