Optional Parameters

[nerdzero]

Brain cramp. What's the syntax for optional parameters? I can't seem to find it despite my searching. This doesn't compile:

#Cobra svn:2790 (post 0.8) / 2012-09-01 on Mono 2.10.8.1 CLR v4.0.30319 on Ubuntu 12.04.1 LTS
class PrintDefault
    def main
        .foo
        .foo(false)

    def foo(bar=true)
        print "[bar]"

Code: Select all

error: Expecting COMMA, but got "=" (ASSIGN) instead.

I've been writing code all day so maybe I just need another pair of eyes.

[Charles]

There is none currently. The work around is to use overloads:

class Foo

    def foo
        .foo(true)

    def foo(bar as bool)
        pass

We'll have them someday, but since the workaround is fairly easy, they are not a high priority.

[nerdzero]

I know why I thought they were. Back when I was looking at the code for the InExpr class I saw some similar syntax. I just checked and found this on line 824 of BinaryOpExr.cobra.

contains = DotExpr(.token, 'DOT', _right, CallExpr(.token, 'contains', List<of Expr>([_left]), true), isImplicit=true)

I remembered seeing the isImplicit=true somewhere but didn't remember the context. I'll use an overload then. Thanks.

[Charles]

When you instantiate a class, you can initialize properties:

class Foo

    pro a from var as String

    pro b from var as int

...

f = Foo(a='bar', b=3)

# instead of:
f = Foo()
f.a = 'bar'
f.b = 3