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Constructing Structures, their uses, and interaction
Posted by formlesstree4,
16 January 2010
·
43 views
vb.net structures interaction
I do not support the usage, selling, buying, or anything to do with illegal drugs.
Structures aren't exactly the easiest thing for someone to get used to. Their concept is really neat, but an example of actually using one is not all that easy to figure out.
The main difference between classes and structures is, classes are reference types and structures are value types. In practical terms, structures are used for smaller lightweight objects that do not persist for long and classes are used for larger objects that are expected to exist in memory for long periods.
I was helping a friend the other day with creating a game system (the game's called Drug Wars, a clone of the Linux/DOS version), and realized that a method for storing information wouldn't work with just Lists & Array's alone. I realized that I should be creating a Structure.
Here's an example of a Class & Structure side by side:
See the difference, or lack thereof? As I said earlier, when one creates a Class, VB.net is expecting the class to persist in memory for quite some time (like the lifetime of the program's execution state), while a Structure is temporary.
Take the game I was helping out with, there has to be a way to store all the "Drug" information, and keep it nice and clean.
I could create a "Drug Class", but why? I don't need an entire Class just to do that. I can create a structure, which is basically like creating another object type (Examples of object types: Strings, Integers, My.Setting variables).
The Structure would need 3 major items: Name, Cost, Description.
Now I have a structure that I can easily create many instances of at low memory costs. On top of that, I can even store them inside lists:
Now I have a fully Object Oriented Structure that I can use (if placed in a publicly available module) anywhere in the program.
That being said, what if I created a different structure that required our current one? For example, the Player. The structure would need...what? Name, Money, Inventory List, and a way to add/remove the drugs from his inventory.
As you can see, the structure code for the Player is MUCH more in-depth, so let me break this down:
There are the regular Properties that you should recognize, such as the ones to Get/Set the Name and Money, but there are some different ones:
There's a WriteOnly Property of adding a Drug. Why not use a sub? There's no real reason I couldn't, it's just a preference really.
The hard one was the removing of the drug. Basically, you pass in the name of the drug, the structure loops through the Inventory list (Which is the List(Of Drug)), and when it finds a matching name, presto, it deletes it, credits the money back, and you're good to go.
As you can see, these two structures are prime examples (Although the usage of them for the game..I don't necessarily agree with) of how structures can be used and how they can interact with each other seamlessly, and call it's own properties within itself.
Feedback is greatly appreciated for my blog posts so I can improve them in the future!
Structures aren't exactly the easiest thing for someone to get used to. Their concept is really neat, but an example of actually using one is not all that easy to figure out.
The main difference between classes and structures is, classes are reference types and structures are value types. In practical terms, structures are used for smaller lightweight objects that do not persist for long and classes are used for larger objects that are expected to exist in memory for long periods.
I was helping a friend the other day with creating a game system (the game's called Drug Wars, a clone of the Linux/DOS version), and realized that a method for storing information wouldn't work with just Lists & Array's alone. I realized that I should be creating a Structure.
Here's an example of a Class & Structure side by side:
Quote
Public Class NewClass
Private Var1 As String
Friend Property Variable1() As String
Get
Return Var1
End Get
Set(ByVal value As String)
Var1 = value
End Set
End Property
End Class
Public Structure NewStruct
Private Var1 As String
Friend Property Variable1() As String
Get
Return Var1
End Get
Set(ByVal value As String)
Var1 = value
End Set
End Property
End Structure
See the difference, or lack thereof? As I said earlier, when one creates a Class, VB.net is expecting the class to persist in memory for quite some time (like the lifetime of the program's execution state), while a Structure is temporary.
Take the game I was helping out with, there has to be a way to store all the "Drug" information, and keep it nice and clean.
I could create a "Drug Class", but why? I don't need an entire Class just to do that. I can create a structure, which is basically like creating another object type (Examples of object types: Strings, Integers, My.Setting variables).
The Structure would need 3 major items: Name, Cost, Description.
Quote
Public Structure Drug
Private DName As String
Private DCost As Double
Private DDesc As String
Friend Property Name() As String
Get
Return DName
End Get
Set(ByVal value As String)
DName = value
End Set
End Property
Friend Property Cost() As Double
Get
Return DCost
End Get
Set(ByVal value As Double)
DCost = value
End Set
End Property
Friend Property Description() As String
Get
Return DDesc
End Get
Set(ByVal value As String)
DDesc = value
End Set
End Property
End Structure
Now I have a structure that I can easily create many instances of at low memory costs. On top of that, I can even store them inside lists:
Quote
Dim DrugList As New List(Of Drug)
Now I have a fully Object Oriented Structure that I can use (if placed in a publicly available module) anywhere in the program.
That being said, what if I created a different structure that required our current one? For example, the Player. The structure would need...what? Name, Money, Inventory List, and a way to add/remove the drugs from his inventory.
Quote
Public Structure Player
Private PName As String
Private PMoney As Double
Private PInventory As List(Of Drug)
Friend Property Name() As String
Get
Return PName
End Get
Set(ByVal value As String)
PName = value
End Set
End Property
Friend Property Money() As Double
Get
Return PMoney
End Get
Set(ByVal value As Double)
PMoney = value
End Set
End Property
Friend WriteOnly Property Add_Drug() As Drug
Set(ByVal value As Drug)
PInventory.Add(value)
End Set
End Property
Friend Function Remove_Drug(ByVal drug As String) As Boolean
Dim count As Integer = 0I
Dim found As Boolean = False
For Each item In PInventory
If item.Name = drug Then
found = True
Exit For
End If
count += 1
Next
Select Case found
Case True
Money += PInventory(count).Cost
PInventory.RemoveAt(count)
End Select
Return found
End Function
End Structure
As you can see, the structure code for the Player is MUCH more in-depth, so let me break this down:
There are the regular Properties that you should recognize, such as the ones to Get/Set the Name and Money, but there are some different ones:
There's a WriteOnly Property of adding a Drug. Why not use a sub? There's no real reason I couldn't, it's just a preference really.
The hard one was the removing of the drug. Basically, you pass in the name of the drug, the structure loops through the Inventory list (Which is the List(Of Drug)), and when it finds a matching name, presto, it deletes it, credits the money back, and you're good to go.
As you can see, these two structures are prime examples (Although the usage of them for the game..I don't necessarily agree with) of how structures can be used and how they can interact with each other seamlessly, and call it's own properties within itself.
Feedback is greatly appreciated for my blog posts so I can improve them in the future!
