On Sun, 02 Aug 2009 20:53:35 -0400, Michel Fortin
<michel.for...@michelf.com> wrote:
On 2009-08-02 20:18:51 -0400, "Robert Jacques" <sandf...@jhu.edu> said:
I also like the idea of omitting parenthesis for functions with no
argument.
I like it too. But the problem with the current approach D are:
1. A syntax that permits function to be called both without and with
empty parenthesis creates ambiguities when it returns a callable type (a
delegate or an object with an opCall member).
2. We want properties to be nouns, and actions to be verbs. In english a
lot of words are both nouns and verbs, which makes it impractical to
distinguish a property from a function by its name alone.
Solving 1 involves having a way to say functions that can and must be
called without parenthesis. Unless we want to force all functions with
no parameter to be called without "()", we must have some kind of flag
to tell us that a function expects or does not expect "()".
Solving 2 involves making a difference in the call syntax between
property and action functions. Since the idea behind a property is to
mimic a field, it follows that the best differentiator for properties is
the lack of parenthesis.
I'd be glad too if we could continue to skip parenthesis for calls to
functions with no arguments, but I think fixing the two problems above
is more important.
I agree 1) is an issue, but I view it as a corner case. (I use zero/one
arg functions all the time and make use of the 'property' syntax left
right and center, but I've never run into the opCall problem) It would be
nice if it were fixed, but we may be cutting off the nose to spite the
face, as it were. (Or alternatively, taking the scientific instead of
engineering approach)
Problem 2) I think is a major logical flaw: a property is a function. So I
see no need to distinguish between the two. Properties, in fact, can be a
very expensive functions that takes locks/do database lock-up/etc. So
making syntax changes that make 'properties' look cheap and 'functions'
look expensive is worse than what we have today. Today, at least, everyone
knows that no parenthesis doesn't mean necessarily cheap O(1) operation.
Solution 1 is what I thought you were proposing. Again, I like it, though
it does make zero-arg function pointers and delegates behave differently
than other functions. And disallowing free_function = expression; would
also address another concern many people have expressed. (Strangely
enough, using the invalid code snippet: writeln = 5)
