[Issue 2002] New: Add keyword for a function definition

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=2002

           Summary: Add keyword for a function definition
           Product: D
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: gaboonviper at gmx.net


Like C and C++, D doesn't have a keyword for function definitions. In C you can
get away with it, since it's a simple language with few possibilities. The
complexity of the C++ and D languages make this approach unsuitable.

Adding a function definition keyword makes the language easier to read.
Consider the following function definition:

int doSomething(int someParam)
{
  ...
}

against

function int doSomething(int someParam)
{
  ...
}

For the second function definition it's immediatly clear that we're declaring a
function here. No need for second glances, this is definitely a function. The
first one on the other is not as intuitive, except perhaps for C/C++
programmers.

While for a simple function the readability improvement may be marginal. When
we consider storage classes and type modifiers, the keyword's influence is much
bigger.

private static const int doSomething(int someParam){}

vs

private static const function int doSomething(int someParam){}

In the first declaration it's a game of 'what belongs to who', whereas the
declaration with the function keyword is a lot more expressive. And with some
good syntax highlighting its effect will be even larger.

It's also more consistent with the rest of D syntax. Especially if you'd ommit
the void type, which the keyword would make possible. 

struct X;
class X;
template X();
function X();
macro X();

So basically using a function definition keyword will decrease the learning
curve needed for D. It will increase the readability of D code. And it could
possibly make it easier to parse.

I hope you will consider implementing it.

Cheers,
Boyd van Oosterhout


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