I'm still messing around with binary heaps. I've successfully created and used it on the function level but for some reason when I move it to the class level I get an error. Furthermore, i'm not entirely sure how to use a binary heap without auto as the type.

class AStar
{
ReferenceNode[] openListContainer;
auto openList = BinaryHeap!(ReferenceNode[], "a.fScore > b.fScore")(openListContainer, 0 ); // Error
}


Error	1	Error: template instance BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") does not match template declaration BinaryHeap(Store,alias less = "a < b") if (isRandomAccessRange!(Store) || isRandomAccessRange!(typeof(Store.init[])))	C:\Users\CP\Documents\Visual Studio 2010\Projects\D\STDS\NPC.d	101	


However this is ok:

class AStar
{
void RandomFunction()
{
ReferenceNode[] openListContainer;
openListContainer.length = 500;
auto openList = BinaryHeap!(ReferenceNode[], "a.fScore > b.fScore")(openListContainer, 0 ); //This is ok
}
}

I'd also like to try this, but can't seem to figure it out:

class AStar
{
ReferenceNode[] openListContainer;
auto openList; //no identifier for declarator openlist

this()
{
openListContainer.length = 500;
openList = = BinaryHeap!(ReferenceNode[], "a.fScore > b.fScore")(openListContainer, 0 );
}
}

If I know what type openList was, after creating the heap, I could simply use that. I tried using typeid( openList ) to find out. I got the type being something like:

BinaryHeap!(Referencenode[], "a.fScore > b.fScore") openList;

However trying to use this as the type gives me this error:


Error	1	Error: template instance BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") does not match template declaration BinaryHeap(Store,alias less = "a < b") if (isRandomAccessRange!(Store) || isRandomAccessRange!(typeof(Store.init[])))	C:\Users\CP\Documents\Visual Studio 2010\Projects\D\STDS\NPC.d	101	


Error	2	Error: BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") is used as a type	C:\Users\CP\Documents\Visual Studio 2010\Projects\D\STDS\NPC.d	101	

I'm just trying to get a variable called openList to the class level so it doesn't keep getting initialized everytime the function is called.

Any ideas on how to work this out?

On 04/04/2012 05:24 PM, Chris Pons wrote:
> I'm still messing around with binary heaps. I've successfully created
> and used it on the function level but for some reason when I move it to
> the class level I get an error. Furthermore, i'm not entirely sure how
> to use a binary heap without auto as the type.
>
> class AStar
> {
> ReferenceNode[] openListContainer;
> auto openList = BinaryHeap!(ReferenceNode[], "a.fScore >
> b.fScore")(openListContainer, 0 ); // Error
> }

To get the type, use an alias. Also, only compile-time expressions can be used to initialize members with in-class initializers. So you must initialize openListContainer in a constructor:

import std.container;

struct ReferenceNode
{
    int fScore() @property
    {
        return 0;
    }
}

class AStar
{
    ReferenceNode[] openListContainer;

    alias BinaryHeap!(ReferenceNode[], "a.fScore > b.fScore") MyBinaryHeap;

    MyBinaryHeap openList;

    this()
    {
        openList = MyBinaryHeap(openListContainer, 0 );
    }
}

void main()
{
    auto as = new AStar();
}

> Error 1 Error: template instance BinaryHeap!(ReferenceNode[],"a.fScore >
> b.fScore") BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") does not
> match template declaration BinaryHeap(Store,alias less = "a < b") if
> (isRandomAccessRange!(Store) ||
> isRandomAccessRange!(typeof(Store.init[]))) C:\Users\CP\Documents\Visual
> Studio 2010\Projects\D\STDS\NPC.d 101
>
>
> However this is ok:
>
> class AStar
> {
> void RandomFunction()
> {
> ReferenceNode[] openListContainer;
> openListContainer.length = 500;
> auto openList = BinaryHeap!(ReferenceNode[], "a.fScore >
> b.fScore")(openListContainer, 0 ); //This is ok
> }
> }

That is ok, because now the initial value need not be a compile-time expression. RandomFunction() gets executed and the right-hand side is evaluatod. Fine.

>
> I'd also like to try this, but can't seem to figure it out:
>
> class AStar
> {
> ReferenceNode[] openListContainer;
> auto openList; //no identifier for declarator openlist

That cannot work. Being a statically-typed language, D must know the exact type of the variables at definition time.

> this()
> {
> openListContainer.length = 500;
> openList = = BinaryHeap!(ReferenceNode[], "a.fScore >
> b.fScore")(openListContainer, 0 );
> }
> }
>
> If I know what type openList was, after creating the heap, I could
> simply use that. I tried using typeid( openList ) to find out. I got the
> type being something like:
>
> BinaryHeap!(Referencenode[], "a.fScore > b.fScore") openList;
>
> However trying to use this as the type gives me this error:
>
>
> Error 1 Error: template instance BinaryHeap!(ReferenceNode[],"a.fScore >
> b.fScore") BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") does not
> match template declaration BinaryHeap(Store,alias less = "a < b") if
> (isRandomAccessRange!(Store) ||
> isRandomAccessRange!(typeof(Store.init[]))) C:\Users\CP\Documents\Visual
> Studio 2010\Projects\D\STDS\NPC.d 101
>
>
> Error 2 Error: BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore") is
> used as a type C:\Users\CP\Documents\Visual Studio
> 2010\Projects\D\STDS\NPC.d 101
>
> I'm just trying to get a variable called openList to the class level so
> it doesn't keep getting initialized everytime the function is called.
>
> Any ideas on how to work this out?

I hope the program above is clear. :)

Ali

Thank you! That helps out quite a bit.

On Thursday, 5 April 2012 at 01:28:12 UTC, Ali Çehreli wrote:
>
> On 04/04/2012 05:24 PM, Chris Pons wrote:
> > I'm still messing around with binary heaps. I've successfully
> created
> > and used it on the function level but for some reason when I
> move it to
> > the class level I get an error. Furthermore, i'm not entirely
> sure how
> > to use a binary heap without auto as the type.
> >
> > class AStar
> > {
> > ReferenceNode[] openListContainer;
> > auto openList = BinaryHeap!(ReferenceNode[], "a.fScore >
> > b.fScore")(openListContainer, 0 ); // Error
> > }
>
> To get the type, use an alias. Also, only compile-time expressions can be used to initialize members with in-class initializers. So you must initialize openListContainer in a constructor:
>
> import std.container;
>
> struct ReferenceNode
> {
>     int fScore() @property
>     {
>         return 0;
>     }
> }
>
> class AStar
> {
>     ReferenceNode[] openListContainer;
>
>     alias BinaryHeap!(ReferenceNode[], "a.fScore > b.fScore") MyBinaryHeap;
>
>     MyBinaryHeap openList;
>
>     this()
>     {
>         openList = MyBinaryHeap(openListContainer, 0 );
>     }
> }
>
> void main()
> {
>     auto as = new AStar();
> }
>
> > Error 1 Error: template instance
> BinaryHeap!(ReferenceNode[],"a.fScore >
> > b.fScore") BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore")
> does not
> > match template declaration BinaryHeap(Store,alias less = "a <
> b") if
> > (isRandomAccessRange!(Store) ||
> > isRandomAccessRange!(typeof(Store.init[])))
> C:\Users\CP\Documents\Visual
> > Studio 2010\Projects\D\STDS\NPC.d 101
> >
> >
> > However this is ok:
> >
> > class AStar
> > {
> > void RandomFunction()
> > {
> > ReferenceNode[] openListContainer;
> > openListContainer.length = 500;
> > auto openList = BinaryHeap!(ReferenceNode[], "a.fScore >
> > b.fScore")(openListContainer, 0 ); //This is ok
> > }
> > }
>
> That is ok, because now the initial value need not be a compile-time expression. RandomFunction() gets executed and the right-hand side is evaluatod. Fine.
>
> >
> > I'd also like to try this, but can't seem to figure it out:
> >
> > class AStar
> > {
> > ReferenceNode[] openListContainer;
> > auto openList; //no identifier for declarator openlist
>
> That cannot work. Being a statically-typed language, D must know the exact type of the variables at definition time.
>
> > this()
> > {
> > openListContainer.length = 500;
> > openList = = BinaryHeap!(ReferenceNode[], "a.fScore >
> > b.fScore")(openListContainer, 0 );
> > }
> > }
> >
> > If I know what type openList was, after creating the heap, I
> could
> > simply use that. I tried using typeid( openList ) to find
> out. I got the
> > type being something like:
> >
> > BinaryHeap!(Referencenode[], "a.fScore > b.fScore") openList;
> >
> > However trying to use this as the type gives me this error:
> >
> >
> > Error 1 Error: template instance
> BinaryHeap!(ReferenceNode[],"a.fScore >
> > b.fScore") BinaryHeap!(ReferenceNode[],"a.fScore > b.fScore")
> does not
> > match template declaration BinaryHeap(Store,alias less = "a <
> b") if
> > (isRandomAccessRange!(Store) ||
> > isRandomAccessRange!(typeof(Store.init[])))
> C:\Users\CP\Documents\Visual
> > Studio 2010\Projects\D\STDS\NPC.d 101
> >
> >
> > Error 2 Error: BinaryHeap!(ReferenceNode[],"a.fScore >
> b.fScore") is
> > used as a type C:\Users\CP\Documents\Visual Studio
> > 2010\Projects\D\STDS\NPC.d 101
> >
> > I'm just trying to get a variable called openList to the
> class level so
> > it doesn't keep getting initialized everytime the function is
> called.
> >
> > Any ideas on how to work this out?
>
> I hope the program above is clear. :)
>
> Ali