Path Finding Using A* in C# 3.0, Part Three

Techy News Blog » Path Finding Using A* in C# 3.0, Part Three

Techy News Blog » Path Finding Using A* in C# 3.0, Part Three — Mon, 08 Oct 2007 17:18:27 GMT

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re: Path Finding Using A* in C# 3.0, Part Three

Blake — Tue, 09 Oct 2007 07:47:13 GMT

Noting the ugly "private SortedDictionary<P, Queue<V>> list = new SortedDictionary<P, Queue<V>>();" led me to wonder - has there been any discussion of supporting 'var' for fields with an initializer like that? At first blush I can't see any risk or breaking change.

re: Path Finding Using A* in C# 3.0, Part Three

Eric Lippert — Tue, 09 Oct 2007 08:05:27 GMT

There is a serious problem with doing so, unfortunately. Namely, what happens when you say

public class Foo {

public var bar = new { Blah = 123 };

? Now you have a public member of a public type which is of an anonymous type. We have carefully designed anonymous types so that they never escape from methods, and this would break that property.

If we allowed that then before you know it, people would want an anonymous type defined in a VB assembly to interoperate with one structurally identical exposed by a C# assembly, and we just don't want to go there.

Until we have a CLR-wide, version-safe strategy for dealing with anonymous types we'll avoid that situation.

Path Finding Using A* in C# 3.0, Part

DotNetKicks.com — Tue, 09 Oct 2007 08:37:21 GMT

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re: Path Finding Using A* in C# 3.0, Part Three

Pablo — Tue, 09 Oct 2007 19:26:20 GMT

Why not just define public var field definations as illegal? and allow the useful private var bar = ... ?

A private field, which is how fields are most of the time, does not have the 'possible escaped anonymous type' issue you raise.

re: Path Finding Using A* in C# 3.0, Part Three

Alan Oursland — Thu, 11 Oct 2007 19:45:08 GMT

Heaps are a nice data structure to use in A* search priority queues. You get an amoratized constant time complexity for insertion and don't have to pay the logn cost until you remove items. Since A* often ends up with a bunch of unexplored nodes on the queue after you find the goal, it saves a bit of time.

Community Convergence XXXIII

Charlie Calvert's Community Blog — Mon, 15 Oct 2007 04:25:34 GMT

Welcome to the thirty-third edition of Community Convergence. This week we have a new video called Programming

re: Path Finding Using A* in C# 3.0, Part Three

filip_sound — Sun, 17 Feb 2008 04:49:35 GMT

SortedDictionary.First(); defined? you're using it like: var pair = list.First(); and also with .Any();

i can not get it running since this method is not declared. what am i doing wrong?

filip

re: Path Finding Using A* in C# 3.0, Part Three

Eric Lippert — Sun, 17 Feb 2008 05:28:53 GMT

Are you using C# 3?

Have you got a "using System.Linq;" directive?

re: Path Finding Using A* in C# 3.0, Part Three

filip_sound — Sun, 17 Feb 2008 05:42:43 GMT

hm sorry, i'm still using c# 2. thanks.

re: Path Finding Using A* in C# 3.0, Part Three

filip_sound — Thu, 28 Feb 2008 02:08:26 GMT

switched to c#3.0 now...

the results increased from 300ms to 15ms for my pathfinder :) great!

MicroQuest – AStar Pathfinding

Marc: My Words — Wed, 25 Jun 2008 17:22:34 GMT

The first thing I want to be able to do in MicroQuest is move my "unit" around the "game

re: Path Finding Using A* in C# 3.0, Part Three

observer — Sat, 28 Mar 2009 20:11:02 GMT

Performance of the SortedDictionary is reportedly very slow. It might be worthwhile to write your own implementation.

http://dotnetperls.com/Content/SortedDictionary.aspx

re: Path Finding Using A* in C# 3.0, Part Three

Vijay — Wed, 13 May 2009 18:25:32 GMT

Can we store multiple same priority items for e.g.

(1, objA)

(1, objB)

(2, objeCJ)

(2, objK)