Need help with lists within types
BlitzMax Forums/BlitzMax Programming/Need help with lists within types
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| I have a particular problem with items that have references to other items imbedded in an internal list. For example, lets say I have four points (of type TPoint). One of those points is linked by a chain to the other three, and the chains have various qualities (like length, strength, etc.). So I create a Type TChain and give it the qualities necessary. I add it to a ChainList:Tlist Field in the TPoint type. Yet, when I iterate through the ChainList for each point, looking for the other points that are chained, I get nothing. The Following sample should show what I'm trying to do. SuperStrict Type TChain Field Size:Int Field Weight:Int Field LinkedPoint:TPoint End Type Type TPoint Field Name:String Field x:Int,y:Int Field ChainList:TList = New TList Method makeChain(Point_in:TPoint,size_in:Int,Weight_in:Int) Local TempChain:TChain = New TChain tempChain.size = size_in tempChain.weight = weight_in tempChain.LinkedPoint = Point_in self.ChainList.addlast(Point_in) End Method Method CheckChains() For Local temp:TChain = EachIn self.ChainList Print temp.LinkedPoint.name Next EndMethod EndType Local Point1:TPoint = New TPoint Point1.name = "Point #1" Local Point2:TPoint = New TPoint Point2.name = "Point #2" Local Point3:TPoint = New TPoint Point2.name = "Point #3" Point1.makeChain(Point2,1,20) Point1.makeChain(Point3,2,40) Point1.checkChains() I originally tried doing this with an array, but it became ugly very quickly... so Tlists seem to be the best option. What am I missing? |
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| the mainproblem from what I see is that you add point_in to the chain insted of tempChain |
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| point_in goes into the tempchain. That way, when needed, I can get the info (such as location, etc.) out of the stored point without having to For-Eachin or otherwise loop through all of the points. For example. Point1 and point2 are connected by a chain. Point1 has a list of all is chains, and each chain stores where its other endpoint is. So Point1's chain would have point2 in its .Linkedto field. That way I can iterate through Point1's Chainlist to find all the points it is attached to, then through Point2's Chainlist to find what it is attached to, etc. |
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| and wherefor do you create tempChain then? as it isn't use anywhere it will simply be destroyed at the end of the function. I think you have a very elemental missdesign in there as it does not do what you say it should in your description. It does not add the point 2 to point 1 chain list and then recursively build that one up ... It adds all to point1s chain and thats it ... there is no chain for point2 ... What you would need is a single reference that points to then next chain element and the checkchain then would go through that "self created" linked list until there is no next chain element anymore. |
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Ooops. You are correct, in that I have a typo on the function. This:Method makeChain(Point_in:TPoint,size_in:Int,Weight_in:Int) Local TempChain:TChain = New TChain tempChain.size = size_in tempChain.weight = weight_in tempChain.LinkedPoint = Point_in self.ChainList.addlast(Point_in) End Method Should be:
Method makeChain(Point_in:TPoint,size_in:Int,Weight_in:Int)
Local TempChain:TChain = New TChain
tempChain.size = size_in
tempChain.weight = weight_in
tempChain.LinkedPoint = Point_in
self.ChainList.addlast(tempChain)
DebugLog "Added Chain"
End Method
However, when you run it, the program only prints "Point #3" when both chains have been added to the list (it should print out points 2&3). What's wrong with the loop to print it out? |
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| OK, I got it to work (I had another typo... Point #3 never got named). So I'm even more confused... because this works here, but not in my larger program. I may have to go back to arrays... |
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