Implementation runtime creates objects dynamically from strings in. Net

Create | dynamic | object | The string params () array is the parameter content table of the constructor method, and also because there are no arguments, we use the ReDim-1 syntax.
　　
The Invoke method executes the construction method and creates an object instance.
　　
Now let's go back to the first implementation and change the code to
　　
Dim T as Type = GetType (myclasstest)
　　
To
　　
Dim T as Type = Type.GetType ("Vbapplication.myclasstest")
　　
The results of the run did not change, that is to say, we implemented the object from the string creation! However, there are restrictions on the use of the GetType method, and we'll talk about it later. Now we can achieve our wish: dynamically creating controls. With the knowledge above, it is easy to write a subroutine that dynamically creates a window control:
　　
Private Function Createnewcontrols (ByVal targetcontrols as Control.controlcollection, ByVal ctlname as String, ByVal CTLT Ype as Type, ByVal ctlsize as Drawing.size, ByVal ctllocation as Drawing.point) as control
　　
Dim Tocreate as Control
　　
Tocreate = CType (System.Activator.CreateInstance (Ctltype), control)
　　
Tocreate.name = Ctlname
　　
Tocreate.size = Ctlsize
　　
Tocreate.location = Ctllocation
　　
Targetcontrols.add (tocreate)
　　
return tocreate
　　
End Function
　　
The longer sentence contains all the contents of the previous example. If you write in C #, you can write
　　
Tocreate = (Control) System.Activator.CreateInstance (Ctltype);
　　
We change the button's event procedure to:
　　
Dim C As Control = ME.CREATENEWCONTROLS1 (Me.Controls, "Control1", GetType (CheckBox), New Size (in), New Point (64, 176) )
　　
C.text = "New creation"
　　
Now, by clicking the button, you can see a new checkbox appearing on the window, titled New Creation, and, if you write an event procedure, you can add an event response for the newly created control.
　　
Looks like everything's up to the end. Note that the GetType (CheckBox) or the literal representation of the class name does not achieve the ability to create objects with strings. If we change this sentence to Type.GetType ("System.Windows.Forms.CheckBox"), can we? Well, try it, hehe, it's a mistake. Why is that? The Type.GetType () method obtains the type from the string to be limited to the type in corlib or the type within the project, and the name of the assembly is required if it is from an external assembly. The Windows.Forms assembly is a public assembly that is located in the assembly cache and can be implemented side by side within the. NET Framwork. So this assembly has a different version, and in order to determine which version to use, we will not only provide the name of the assembly, but also the version and strong name of the assembly. In this way, on the. NET Framework 1.1 that I use, I write this sentence as Type.GetType ("System.Windows.Forms.CheckBox, System.Windows.Forms, version= 1.0.5000.0, Culture=neutral, publickeytoken=b77a5c561934e089 "). There is no problem with running now. The question is how do we get the version and strong name of the Windows.Forms assembly we use? You can use GetType (CheckBox). AssemblyQualifiedName Such syntax, once this information is available, we can use that information for any other control, since they all come from the same version of the Windows.Forms assembly. Now you can play a fun, put a text box to the window, such as called TextBox1, the button's event procedure to read:
　　
Try
　　
Dim C As Control = ME.CREATENEWCONTROLS1 (Me.Controls, "Control1", Type.GetType ("System.Windows.Forms." & TextBox1.Text & ", System.Windows.Forms, version=1.0.5000.0, Culture=neutral, publickeytoken=b77a5c561934e089"), New Size (in), New Point (64, 176))
　　
C.text = "New creation"
　　
Catch ex as Exception
　　
MsgBox (ex. Message)
　　
End Try
　　
Now just type in the TextBox1 type "button", press the button, a new button produced! If you enter a checkbox, a check box is generated. Now, no matter how difficult the user is, the control can be "created on demand" correctly. The reflection mechanism has many uses in. NET, and it is said that features such as class references and virtual constructors in Delphi.NET are used for. NET Framwork with the help of reflection and System.Type types, and the use of this sharp weapon will add a lot to your program.