public, static & friends

[neuruss]

Hi there,

Just a couple of questions:
1) How do I declare public members? The only way I found to access directly class variables is by creating properties...
2) In c#, if I declare a method as static, then I would simply use it by prepending the name of the class ( classname.method() ).
However, in Cobra I cannot use this method if I don't instantiate the class first. Why?

neuruss

[RichS]

newruss,

Are you looking for the "as shared" modifier (not sure what it's called)?

Code: Select all

$ cat hello.cobra
class Hello

    def hi is shared
        print 'hello, world.'

class Program

    def main is shared
        Hello.hi

$ cobra -c hello.cobra
Compilation succeeded

$ mono hello.exe
hello, world.


[neuruss]

Rich,

You are right! Actually I asked the wrong question..
I was having problem accessing a static member, not a method.

For example, I have a class "Dude" (see the code below) were I defined a shared variable "lista", which is a list of type Dude.
Everytime an instance of Person is created, it adds itself to lista.
In c# I would simply access it this way: Person.lista , but in Cobra, the compiler indicates that I should create an instance in order to access it.

Trying to access it directly as above throws the following error:

hello2.cobra(7): error: Cannot access instance member "lista" on type "Dude". Ma
ke the member "shared" or create an instance of the type.
Compilation failed - 1 error
Not running due to errors above.

class Dude
    shared
        var _lista = List<of Dude>()

    var _name as String
    var _last as String
    var _age as int
    
    def init(n as String, l as String, a as int)
        _name = n.toUpper
        _last = l.toUpper
        _age = a
        _lista.add(this)

    pro lista from var

    def toString as String is override
        return '[_name] [_last]'

[RichS]

neuruss,

Is it worked for me a bad answer?

Code: Select all

$ cat dude.cobra
class Dude
    shared
        var _lista = List<of Dude>()

    var _name as String
    var _last as String
    var _age as int

    def init(n as String, l as String, a as int)
        _name = n.toUpper
        _last = l.toUpper
        _age = a
        _lista.add(this)

    pro lista from var

    def toString as String is override
        return '[_name] [_last]'

class Program

    def main is shared
        Dude('a','b',1)
        Dude('c','d',2)
        dudes=Dude('e','f',3)
        for d in dudes.lista
            print d

$ cobra -c dude.cobra
Compilation succeeded
$ mono dude.exe
A B
C D
E F


[neuruss]

It worked, but you actually created an instance of Dude (dudes).
What I mean is why can't I just access "lista" by simply prepending the classname, instead of having to instantiate the class.

For example:

for d in Dude.lista
            print d

Do you know what I mean?

[RichS]

I do now.

I get the same error if I don't make an instance.

I'm too much of a programming rookie, it wouldn't occur to me not to use an instance.

I come from a mostly Python background.

[neuruss]

Well, I come from Python too, which is the only language I know fairly well (as a simple hobbyist).
I learned a little bit of c# while trying to understand Boo and static typing ...

[RichS]

Got it!

Code: Select all


    shared
        var _lista = List<of Dude>()
        pro lista from var



and it works.

[Charles]

Glad you guys worked this out while I was sleeping.

By the way, in your posts, if you use (cobra) ... (/cobra) tags instead of (code) ... (/code) then someday we'll have syntax highlighting. Of course, BBCode uses square brackets, not parens, which I only use for explanation so you can see the tags.

[neuruss]

How is it possible?
I keep on getting an error.

If you see above, I had already typed "pro lista from var".
Now I tried placing it right below the shared var declaration, but it doesn't work either...