Hi,

how i can control what writeln outputs when I pass an object parameter?

Thanks,
Bogdan

On Thursday, 18 April 2013 at 17:36:10 UTC, gedaiu wrote:
> Hi,
>
> how i can control what writeln outputs when I pass an object parameter?
>
> Thanks,
> Bogdan

You can override the toString() method, like this http://dpaste.dzfl.pl/db7dbe28

On Thursday, 18 April 2013 at 17:42:53 UTC, JN wrote:
> On Thursday, 18 April 2013 at 17:36:10 UTC, gedaiu wrote:
>> Hi,
>>
>> how i can control what writeln outputs when I pass an object parameter?
>>
>> Thanks,
>> Bogdan
>
> You can override the toString() method, like this http://dpaste.dzfl.pl/db7dbe28

i've done that but i get this error:

Error: function base.Value.Value.toString cannot override a non-virtual function
Error: function base.Value.Value.toString override only applies to class member functions

On 4/18/13, gedaiu <szabobogdan@yahoo.com> wrote:
> i've done that but i get this error:
>
> Error: function base.Value.Value.toString cannot override a
> non-virtual function
> Error: function base.Value.Value.toString override only applies
> to class member functions
>

If it's a struct then don't put "override".

On Thursday, 18 April 2013 at 18:04:03 UTC, Andrej Mitrovic wrote:
> On 4/18/13, gedaiu <szabobogdan@yahoo.com> wrote:
>> i've done that but i get this error:
>>
>> Error: function base.Value.Value.toString cannot override a
>> non-virtual function
>> Error: function base.Value.Value.toString override only applies
>> to class member functions
>>
>
> If it's a struct then don't put "override".

Just to provide a bit more info:

Classes all derive from Object, which defines toString. Hence, you need to override it to define your own.

Structs don't have a parent (or any inheritance at all) and hence you don't override anything, you just define the method.

On Thursday, 18 April 2013 at 18:25:21 UTC, John Colvin wrote:
> On Thursday, 18 April 2013 at 18:04:03 UTC, Andrej Mitrovic wrote:
>> On 4/18/13, gedaiu <szabobogdan@yahoo.com> wrote:
>>> i've done that but i get this error:
>>>
>>> Error: function base.Value.Value.toString cannot override a
>>> non-virtual function
>>> Error: function base.Value.Value.toString override only applies
>>> to class member functions
>>>
>>
>> If it's a struct then don't put "override".
>
> Just to provide a bit more info:
>
> Classes all derive from Object, which defines toString. Hence, you need to override it to define your own.
>
> Structs don't have a parent (or any inheritance at all) and hence you don't override anything, you just define the method.

i'm realy sorry... it's my mistake...

i have a struct not an object. I have someting like this when i get the error:

struct Value {
	string strVal;

        this(string val) {
		strVal = val;
	}

        override string toString() {
		return strVal;
	}
}

Just drop the override:

> struct Value {
>     string strVal;
> 
>         this(string val) {
>         strVal = val;
>     }
> 
>         override string toString() {
>         return strVal;
>     }
> }


struct Value {
    string strVal;

        this(string val) {
        strVal = val;
    }

    string toString() {
        return strVal;
    }
}

On Thursday, 18 April 2013 at 18:46:09 UTC, gedaiu wrote:
> i have a struct not an object.

There's a slight nomenclature clash here:

Object is the base class in D. Therefore one could say that an object is an instatiation of Object and therefore a class.

However, by a wider definition of the word, a struct could also be said to be an object.

On 04/18/2013 12:37 PM, John Colvin wrote:

> However, by a wider definition of the word, a struct could also be said
> to be an object.

You are missing some words there. :) Not a struct itself, but instances of it are said to be objects.

Ali

Ok, i understand now the diference...

my question is how I should solve this problem?

Thanks,
Bogdan

On Thursday, 18 April 2013 at 20:57:23 UTC, Ali Çehreli wrote:
> On 04/18/2013 12:37 PM, John Colvin wrote:
>
> > However, by a wider definition of the word, a struct could
> also be said
> > to be an object.
>
> You are missing some words there. :) Not a struct itself, but instances of it are said to be objects.
>
> Ali