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public, static & friends

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public, static & friends

Postby neuruss » Sat Feb 09, 2008 9:19 am

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
neuruss
 
Posts: 23

Re: public, static & friends

Postby RichS » Sat Feb 09, 2008 9:41 am

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.
RichS
 
Posts: 8

Re: public, static & friends

Postby neuruss » Sat Feb 09, 2008 10:01 am

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]'
neuruss
 
Posts: 23

Re: public, static & friends

Postby RichS » Sat Feb 09, 2008 10:34 am

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
RichS
 
Posts: 8

Re: public, static & friends

Postby neuruss » Sat Feb 09, 2008 10:42 am

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?
neuruss
 
Posts: 23

Re: public, static & friends

Postby RichS » Sat Feb 09, 2008 11:25 am

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.
RichS
 
Posts: 8

Re: public, static & friends

Postby neuruss » Sat Feb 09, 2008 11:31 am

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 ... :-)
neuruss
 
Posts: 23

Re: public, static & friends

Postby RichS » Sat Feb 09, 2008 11:47 am

Got it!

Code: Select all

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



and it works.
RichS
 
Posts: 8

Re: public, static & friends

Postby Charles » Sat Feb 09, 2008 12:18 pm

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.
Charles
 
Posts: 2510
Location: Los Angeles, CA

Re: public, static & friends

Postby neuruss » Sat Feb 09, 2008 12:22 pm

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...
neuruss
 
Posts: 23

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