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digitalmars.D.learn - Binary Heap Errors Class level vs function level

reply "Chris Pons" <cmpons gmail.com> writes:
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?
Apr 04 2012
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
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
Apr 04 2012
parent "Chris Pons" <cmpons gmail.com> writes:
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
Apr 04 2012