Cloning of objects in VB.NET
Hou Yongfeng
Inside 3DMAX, after a good object (parent), you can select Clone in the EDIT menu. There are three options below: Copy (generated a child of the same appearance, the operation does not affect each other), instance (father and child interact The operation of the parent also affects the child, the child is also the same as the child), and there is a Reference (not considered).
In VB.NET, you will also encounter such problems. Create an instance of a complex object (there may be many different data types), after a series of operations, want a middle variable or several (additional instances) to save its status, we generally take a variable value assignment, When you write a long code :) This is actually the above copy problem. For instance, it is very simple, create a new instance, pointing to it:
DIM OBJA AS New CRESUME 'CRESUME is a customized record resume information class
Then initialize, for example:
Obja.name = "aaa"
Obja.address = "Shanghai, China"
......
Dim objb as new cresume 'New an instance
Objb = Obja
In this case, Objb has the same state as Obja, it is worth noting that OBJB changes a Name, such as:
Objb.name = "bbb"
In fact, Obja's NAME has also become "BBB", and the reason is very simple. They point to the same memory space.
Below we focus on discussing the Clone problem of the object, that is, each object after COPY does not affect each other. How is the key to solve our problems, MemoryStream and Binformatter can simply clone objects.
MemoryStream, I have previously mentioned that the stream supporting the storage area is memory.
Binformatter, mainly serialized and reverse sequenced in binary form.
Main ideas:
First use binformatter's Serialize method, store objects in the MemoryStream stream (the same as other stream), then Deserialize deceased, get a streaming data, converted to the original object. Is not it simple? Ha ha. Look at the code and say:
CRESUME class code:
Imports system.io
Imports system.Runtime.Serialization.Formatters
'Attention to the front plus the serializable () attribute, otherwise you can not serialize
DIM M_NAME AS STRING 'Name
DIM M_ADDRESS AS STRING '
Public property address () AS String
Get
Return M_Address
END GET
Set (ByVal Newaddress As String)
m_address = newaddress
End set
End Property
Public property name () AS STRING
Get
Return M_NameEnd Get
Set (byval newname as string)
m_name = newname
End set
End Property
Public Function Clone () AS CRESUME
Dim bf as new binary.binaryformatter ()
DIM MS as new memoryStream ()
Bf.Serialize (MS, ME)
Ms.position = 0
Return (ctype (BF.DSERIALIZE (MS), CRESUME)
END FUNCTION
END CLASS
Calling in Form
Dim Resume1 As New Creesume ()
Dim Resume2 As New Cresume ()
Resume1.name = "aaa"
Resume1.address = "
Shanghai
,
China
"
Resume2 = resume1.clone ()
Resume1.name = "bbb"
Resume1.address = "
Beijing
,
China
"
Debug.writeline (resume1.name) 'is still AAA
Debug.writeLine (resume1.address)
Summary: Mainly call the stream and serialization technique of VB.NET, so that the clone of the object is removed from cumbersome read and write operations, but also simplifies the code.
