Disclaimer:
None of the techniques used here are new to our community and you may have seen the 'Trick' used by me before.
The Problem:
We are using classes more frequently, especially with B4XPages. After laboriously creating an instance
of a class, we often need another one just like it (except prehaps for some small differences).
We know how to create a Clone Sub in the Class that will spawn another instance.
If the class has few properties we can do this manually.
However, Classes can become complex with numerous properties and variables.
These can be arrays, and other structures that can be difficult to copy.
The Trick:
In the IDE we copy the properties section and paste it into a Smart String
By parsing and processing "propsToClone" we can generate "copying code" for the Clone Sub
This code is put on the Clipboard, available for pasting in the Clone Sub.
You'll see that the generated code relies on a number of helper functions. One requires the RandomAccessFile library.
The Example with the CloningCodeToClipboard Sub, and Helper Subs is attached as a .zip file.
The use of the example above...
For Consideration:
Manipulating code like this should be considered as a possible time saver, but is not generally recommended.
It could lead to errors (for example: was there or will there be something unexpected on the Clipboard?).
I'll use it, since I am very methodical in how I code, and I check and test every step of the way.
Finally, the attachment has a series of Helper Subs that are useful in their own right. Take a look.
Feedback is welcome.
None of the techniques used here are new to our community and you may have seen the 'Trick' used by me before.
The Problem:
We are using classes more frequently, especially with B4XPages. After laboriously creating an instance
of a class, we often need another one just like it (except prehaps for some small differences).
We know how to create a Clone Sub in the Class that will spawn another instance.
B4X:
'In use: Dim Instance2 as ClassName = Instance1.Clone
'In ClassName:
Public Sub Clone As ClassName
Dim newInstance as ClassName
newInstance.Initialize
newInstance.propertyX = propertyX
'etc.
return NewInstance
End SubIf the class has few properties we can do this manually.
However, Classes can become complex with numerous properties and variables.
These can be arrays, and other structures that can be difficult to copy.
The Trick:
In the IDE we copy the properties section and paste it into a Smart String
B4X:
Sub Class_Globals
Private fx As JFX
Private xui As XUI
Private ser As B4XSerializator
'Properties and variables for cloning
Private mNames() As String
Private mAge, mHeight As Int
Private mChildren As List
Private mBox As B4XView
Public OnState As Boolean
Private i = 0, j = 2, k = 5 As Int 'ignore
Private txt = "test" As String, value = 1.05 As Double, flag = False As Boolean 'ignore
'Smart string version
Private propsToClone As String = $"
Private mNames() As String
Private mAge, mHeight As Int
Private mChildren As List
Private mBox As B4XView
Public OnState As Boolean
Private i = 0, j = 2, k = 5 As Int 'ignore
Private txt = "test" As String, value = 1.05 As Double, flag = False As Boolean 'ignore
"$
End SubBy parsing and processing "propsToClone" we can generate "copying code" for the Clone Sub
This code is put on the Clipboard, available for pasting in the Clone Sub.
B4X:
Public Sub Initialize(FirstName As String, LastName As String)
mChildren.Initialize
mNames = Array As String(FirstName, LastName)
OnState = True
End Sub
Public Sub Clone As classA
CloningCodeToClipboard 'The Smart string version is parsed and code is generated and placed on clipboard.
Dim newInstance As classA
newInstance.Initialize(mNames(0), mNames(1))
'After 1st attempt at cloning, paste clipboard contents below.
'_____________________________I have pasted the contents of clipboard, before I did that this section was empty
newInstance.mNames = copyStringArray(mNames)
newInstance.mAge = mAge
newInstance.mHeight = mHeight
newInstance.mChildren = copyStructure(mChildren)
newInstance.mBox = copyPanel(mBox)
newInstance.OnState = OnState
newInstance.i = i
newInstance.j = j
newInstance.k = k
newInstance.txt = txt
newInstance.value = value
newInstance.flag = flag
'_____________________________
Return newInstance
End SubYou'll see that the generated code relies on a number of helper functions. One requires the RandomAccessFile library.
The Example with the CloningCodeToClipboard Sub, and Helper Subs is attached as a .zip file.
The use of the example above...
B4X:
Private Sub demonstrate
Dim InstanceA As classA
InstanceA.Initialize("Alpha", "Beta")
InstanceA.Age = 45
InstanceA.Height = 181
InstanceA.MakeBox
Dim InstanceB As classA = InstanceA.Clone
'If the class is a B4XPage then you need to register it with B4XPages.AddPage now.
InstanceB.Age = 75
InstanceB.AddChild("William")
InstanceB.AddChild("Suzanna")
Log(InstanceA.Names(0) & TAB & InstanceA.Names(1) & TAB & InstanceA.Age & TAB & InstanceA.Height & TAB & InstanceA.Children.Size)
Log(InstanceB.Names(0) & TAB & InstanceB.Names(1) & TAB & InstanceB.Age & TAB & InstanceA.Height & TAB & InstanceB.Children.Size)
Log(InstanceB.Box.Width)
' Alpha Beta 45 181 0
' Alpha Beta 75 181 2
' 300
End SubFor Consideration:
Manipulating code like this should be considered as a possible time saver, but is not generally recommended.
It could lead to errors (for example: was there or will there be something unexpected on the Clipboard?).
I'll use it, since I am very methodical in how I code, and I check and test every step of the way.
Finally, the attachment has a series of Helper Subs that are useful in their own right. Take a look.
Feedback is welcome.
Attachments
Last edited:
