digitalmars.D.learn - clear initializing constructor
- Saaa (17/17) Aug 04 2008 How do you do something like this?
- Wyverex (20/45) Aug 04 2008 class Fruit
How do you do something like this?
class Fruit
{
protected struct _Eigen
{
byte color = GREEN;
bool rotten = false;
}
private _Eigen eigen;
this(...)
{
// ?
}
}
apple=new Fruit(color=RED,rotten=false);
apple2=new Fruit(rotten=true);
apple3=new Fruit(pit=false); //pit=ignored
Aug 04 2008
Saaa wrote:
How do you do something like this?
class Fruit
{
protected struct _Eigen
{
byte color = GREEN;
bool rotten = false;
}
private _Eigen eigen;
this(...)
{
// ?
}
}
apple=new Fruit(color=RED,rotten=false);
apple2=new Fruit(rotten=true);
apple3=new Fruit(pit=false); //pit=ignored
class Fruit
{
protected struct _Eigen
{
byte color = GREEN;
bool rotten = false;
}
private _Eigen eigen;
this()
{
}
this(bool rotten, byte color)
{
eigen.rotten = rotten;
eigen.color = color;
}
}
auto apple = new Fruit( false, RED );
auto normal = new Fruit();
Aug 04 2008
Thanks for your reply.
But I think I wasn't clear in my question.
As _Eigen can get quite large I think it is necessary to have something
like:
apple=new Fruit(color=RED,rotten=false);
otherwise thinks like this will happen:
apple=new Fruit(,,,RED,,false,,true etc.);
class Fruit
{
protected struct _Eigen
{
byte color = GREEN;
bool rotten = false;
}
private _Eigen eigen;
this()
{
}
this(bool rotten, byte color)
{
eigen.rotten = rotten;
eigen.color = color;
}
}
auto apple = new Fruit( false, RED );
auto normal = new Fruit();
Aug 04 2008
Not directly you can do something like
struct test
{
bool A;
int B;
float C;
}
class foo
{
private test t;
this(test bar)
{
t = bar;
}
}
void main()
{
static test t = { A:true, C:4.5 };
foo f = new foo( t);
}
But the static struct has to be filled by constants..
But it sounds like you might be better off using inheritance..
create a base Fruit class that you inherit and modify needed data..
Saaa wrote:
Thanks for your reply.
But I think I wasn't clear in my question.
As _Eigen can get quite large I think it is necessary to have something
like:
apple=new Fruit(color=RED,rotten=false);
otherwise thinks like this will happen:
apple=new Fruit(,,,RED,,false,,true etc.);
class Fruit
{
protected struct _Eigen
{
byte color = GREEN;
bool rotten = false;
}
private _Eigen eigen;
this()
{
}
this(bool rotten, byte color)
{
eigen.rotten = rotten;
eigen.color = color;
}
}
auto apple = new Fruit( false, RED );
auto normal = new Fruit();
Aug 04 2008
"Saaa" <empty needmail.com> But the static struct has to be filled by constants..Yeah, not too usefull for my program :)But it sounds like you might be better off using inheritance.. create a base Fruit class that you inherit and modify needed data..Will that not take just as much code as modifying the needed data within the objects? Or aren't I getting it :) All permutations of possible settings should be possible.
Aug 04 2008
This will work, but is maybe a tad eleborate :)
apple=new Fruit("color",RED,"rotten",false);
Aug 04 2008
Saaa wrote:
This will work, but is maybe a tad eleborate :)
apple=new Fruit("color",RED,"rotten",false);
Two more thoughts...
Use with. not as clean looking and requires write access to data
http://www.digitalmars.com/d/1.0/statement.html#WithStatement
Foo = new Fruit;
with(Foo)
{
rotten = true;
color = YELLOW;
taste = SWEET;
bitesLeft = nBites; //variable
}
the other is a mixin, I've never really messed with them but something
like below.. But the string has to be evaluated at compile time...
http://www.digitalmars.com/d/1.0/statement.html#MixinStatement
badBerry = new Fruit( "rotten = true; color = BLUE" );
class Fruit
{
this(const char[] type)
{
mixin(type);
}
.....
Aug 04 2008
Thanks, I was looking at mixin myself but the compile time evaluating didn't work for me. I totally forgot about 'with', might at least make it more compacted together. I just wanted it like in R .. :)
Aug 04 2008