As I am trying to figure out how to work with the Siemens Tia Portal Openness framework, I try to find an item in my Tia Portal project with the ControllerTarget type.
I try to find the items like this:
Imports Siemens.Engineering
Imports Siemens.Engineering.HW
Module Module1
Sub Main()
Dim myTiaPortal
myTiaPortal = New TiaPortal(TiaPortalMode.WithoutUserInterface)
'The portal is open, now create a project.
Dim tiaProject As Project
'Open the sample project:
Dim fileName As String
fileName = "C:\Path\To\Project\Sample_Project.ap13"
tiaProject = myTiaPortal.Projects.Open(fileName)
'Get the frist device from the project:
Dim tiaDevice As Device
tiaDevice = tiaProject.Devices.First
For Each item As IDeviceItem In tiaDevice.DeviceItems
Console.WriteLine(item.GetType())
Next
Console.ReadKey()
End Sub
End Module
This shows two items in the project:
Siemens.Engineering.HW.DeviceItemImplementation
Siemens.Engineering.HW.ControllerTargetImplementation
When I try to define an object of the type ControllerTargetImplementation I get the message that this datatype does not exist.
When I try to convert the item of type ControllerTargetImplementation to an object of type ControllerTarget, this seems to work perfectly.
Does this mean that the type returned by GetType() does not have to be the same as the actual type of the object? Is this normal? Or is this a strange thing in the openness platform?
When I try to define an object of the type ControllerTargetImplementation I get the message that this datatype does not exist.
Types can be internal to an assembly, which means that while they exist and things like GetType will show them to be there, you can't use them directly.
When I try to convert the item of type ControllerTargetImplementation to an object of type ControllerTarget, this seems to work perfectly.
Given the names involved here, it certainly sounds like ControllerTarget is the type being exposed to you, the consumer of the library, while the implementation of that type, perhaps a subclass or an implementation of an interface (ie is ControllerTarget a class or interface?) is hidden from you as you don't need to know about how it does it's job, nor interfere with it.
Does this mean that the type returned by GetType() does not have to be the same as the actual type of the object?
The actual type of the object is what is reported by GetType, but that doesn't mean that it's necessarily what you refer to it as. For instance, consider the following:
Class A
End Class
Class B
Inherits A
End Class
Sub Main
Dim obj as A = new B()
Console.WriteLine(obj.GetType())
End Sub
This will report obj as having a type of B (because that's the actual type we instantiated with new B()), even though it's stored against a variable of type A.
Related
I want to make the same operations on different lists of controls of specific types. I could do it one type at a time, but I figured: "There's a bunch of these, so why not do this in a loop?" and now of course I'm wondering where I went wrong. The problem can be reproduced easily:
Dim myType As Type = GetType(TextBox)
Dim newList As New List(Of myType) ' this is not allowed
This is the specific error message: BC30002: Type 'currentType' is not defined
Is there a way to use an object of the Type class as a type, or to do a similar maneuver which would let me do something like this:
For Each currentType As Type In {GetType(myCustomType), GetType(anotherCustomClassType)}
Dim newList As New List(Of currentType)
' do stuff
Next
No there isn't. When you create a generic List, you must specify a data type. A Type object is not a data type. It's an object that contains information about a data type. Basically, when you create a List(Of T) you can only fix T to be something that you could have passed to GetType in the first place. Both require data types.
You can't put data types in a list because they are not objects. What you could do is write a generic method that does what you want for one type, e.g.
Private Sub DoStuff(Of T)()
Dim newList As New List(Of T)
'Do stuff here.
End Sub
and then call that method and specify different generic types, e.g.
DoStuff(Of SomeType)()
DoStuff(Of SomeOtherType)()
'Etc.
You have to make individual calls though, because you need to specify the generic type.
This question already has answers here:
Classes vs. Modules in VB.NET
(8 answers)
Closed 3 years ago.
I want convert a C# code to vb.net console.
This is first time I find this two type code structure.
1.
Namespace ConsoleApp4
Module Program
Public Sub Main(ByVal args As String())
test()
End Sub
sub test()
end sub
End Module
End Namespace
2.
Namespace ConsoleApp4
Class Program
Public Shared Sub Main(ByVal args As String())
test()
End Sub
shared sub test()
end sub
End Class
End Namespace
what is the difference of this two type?
Sub Main must be shared to work as entry point of the application. It is automatically shared (or static) in modules. In classes the Shared keyword is required.
A VB module corresponds to a C# static class. Static classes and modules have only static members that can be used without having to create an object. In contrast, a non-static class must be instantiated to access its non-static (C#) or non-shared (VB) members
Module M
Public Function F(ByVal x As integer) As Integer
Return x * x
End Function
End Module
Class C
Public Function T(ByVal x As Integer) AS Integer
Return x + 10
End Function
End Class
With these declarations, you can write
Dim r1 As Integer = M.F(5) ' Or simply F(5) '
Dim o As C = New C() ' Must instantiate class, i.e., create an object.'
Dim r2 As Integer = o.T(32)
If you have variables (or properties) in a module, those exist exactly once. You can, however, create many objects from the same class and each object will contain another copy of these variables
Public Class Person
Public Property FirstName As String
Public Property LastName As String
End Class
Using this class declaration you can write
Dim list As New List(Of Person)()
list.Add( New Person With { .FirstName = "Terry", .LastName = "Adams"} )
list.Add( New Person With { .FirstName = "Lisa", .LastName = "Jones"} )
For Each p As Person In list
Console.WriteLine($"Person = {p.FirstName} {p.LastName}")
Next
Now you have two Person objects in the list having different first and last names.
Classes belong to Object-oriented programming (OOP). I suggest you to read some introductions about it, as .NET is mainly based on OOP concepts.
See also:
Object-oriented programming (Visual Basic)
Explain Object Oriented Programming in VB.NET
The difference between a Module and a Class is subtle; there is only ever one instance of a Module in all your program's life, and you cannot make multiple instances of it using the New keyword. By contrast you have to make an instance of a Class before you can use it..
In order to run, the .net framework runtime has to be able to find an available Main method without having to create an instance of a Class. This is achieved either by having the Main be kept inside a Module (and thus the Main is available because the module is available without having to instantiate a Class) or having it declared as Shared and be inside a Class (in which case you can conceive that a special thing happens that makes the shared Subs available without a class instance)
It's a hard difference to explain if you're not really well introduced to the concepts of OO programming and what "instances" actually means:
Class Person
Public Name as String
Public Sub New(n as String)
Name = n
End Sub
End Class
This declares a class of type person. Nothing about it refers to a particular person and it doesn't cause any Person object to exist in the computer memory until you use New:
Dim cj as New Person("Caius Jard")
Dim g as New Person("gxmgxm")
g.Name = "gsmgxm" 'correct a typo! this edits the name in the g object. it leaves cj's name alone
Now two instances of a Person object are in your computer memory, one named for me and one for you. You cannot do this with a Module. If we'd declared Person as Module there would only be one of them in all the entire program, accessed by the reference "Person":
Person.Name = "Caius Jard"
Person.Name = "gsmgxm" 'this overwrites my name. The program cannot remember more than one Person
and we couldn't have multiples. Consider that, at the time you launch your program, the runtime finds everything that is declared to be a Module and creates just one of them. This is somewhat vital for all sorts of advanced reasons that I won't get into, and Modules definitely do have their place in the grand scheme of things but thy aren't always incredibly useful in OO programming because more of the time we want more than one instance of a thing so we can model multiple things simultaneously.
So that's a precis on Class vs Module and why they are. In order to call any Sub or Function, you have to be able to call it on something. You have to have a DVD player before you can put a DVD in it and press Play - equally in programming, you have to have something that you can put your Main sub on, so you (or the .net runtime) can refer to it with Program.Main() and execute the instructions of the Sub.. That's how Subs and Functions work - theyre either associated with the special single instance (if it's a Module or a Shared Sub/Function of a Class), or they're associated with some object instance in the computer memory, and calling the Sub/Function acts on the object instance that was referred to:
Class Person
Public Name as String
Public Sub SetNameBlank()
Name = ""
End Sub
End Class
cj.SetNameBlank() 'the name of the cj object we declared before, is now blank
g.SetNameBlank()
By specifying the object instance name cj then the Sub name, we establish context - the actions listed in SetNameBlank will be carried out against the cj object, not the g one. If we'd declared SetNameBlank as Shared then they would have taken place in the shared context, not related to either cj or g, and Shared SetNameBlank() could be invoked without cj or g even existing
Going back to the reason you're asking your question right now, what the difference between these two (in the context of a "Main" Sub), the answer is..
..is "not much" from the perspective of getting your app going. Either approach is fine. Your Main method will have to start kicking things off my making object instances of the other Classes you have in your program and getting them to do things. It probably wont make new instances of the class that your Main is in so right now it doesn't really matter whether you put your main in a module or a class - it achieves the same end result that there is a Sub the runtime can call into to start things moving, without needing to create an instance of a Class first
https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/program-structure/main-procedure
Compile Error:
Compile Error: Only user-defined types defined in public object
modules can be coerced to or from a variant or passed to a late-bound
functions.
I'm new to VBA and I was tasked with debugging some code for a custom screen in Dynamics SL. The first thing I did was to see if it compiled and I got the above message.
When I read the built-in help reference I found the following for the above error:
You attempted to use a public user defined type as a parameter or
return type for a public procedure of a class module, or as a field of
a public user defined type. Only public user defined types that are
defined in a public object module can be used in this manner.
I also went through these similar questions:
How to put user defined datatype into a Dictionary
Only user-defined type defined in public object modules can be coerced when trying to call an external VBA function
They have the same error but I don't see a collection object that the above two questions focused on.
If you may have any idea what may be causing this error please don't hesitate to suggest it.
Code:
Private Sub cpjt_entity_Chk(ChkStrg As String, retval As Integer)
Dim ldDate As Sdate
Dim xStrDailyPost As Sdate
ldDate.val = GetObjectValue("cpe_date")
'xStrDailyPost = DateToStr(ldDate)
'Call MsgBox("Daily Post Date: " & xStrDailyPost, vbOKOnly, "TEST")
serr1 = SetObjectValue("cld_id08", xStrDailyPost) <- Error highlights "xStrDailyPost"
End Sub
Definition for SetObjectValue:
Declare Function SetObjectValue Lib "swimapi.dll" Alias "VBA_SetObjectValue" (ByVal ctlname$, newval As Variant) As Integer
Thank you in advance!
You are probably working with code that was originally written with the Dynamics SL (actually it was Solomon IV at the time) Basic Script Language (BSL) macro language instead of VBA.
Regardless... the fix is, pass results of the "val" method of your xStrDailyPost instance of SDate. SO the code should look like:
serr1 = SetObjectValue("cld_id08", xStrDailyPost.val)
I've not actually tested this but I'm pretty sure this will address your issue.
If you want a little more background, "Sdate" is really just a very thin wrapper of an integer (actually I think it's a short, but I've never found I really needed to know for sure). the "Val" method returns the underlying integer in the SDate variable.
I am working with a COM library in Visual Basic (VB.NET). I am trying to get a list of properties associated with an Interface; however, I am not able to get a list of interface properties. Can someone direct me on the best way to list properties on an Interface?
Below is some sample code that loops over all the properties of a class called "TextBox". The output from this code is a list all the class properties.
This particular code doesn't seem to work for interfaces. By this I mean that this code doesn't return the properties of an interface.
Dim txt As New TextBox
Dim type As Type = txt.GetType()
Dim properties() As PropertyInfo = type.GetProperties()
For Each p As PropertyInfo In properties
OutputWindow(p.Name)
Next
Image of COM Library with Interface HYSYS.Valve
Just replace txt.GetType() with the GetType() operator to specify type names instead:
Dim type As Type = GetType(HYSYS.Valve)
You would only use <object>.GetType() when you already have an existing instance of an object. To get the properties of a type in general, for instance a TextBox, it is better to do GetType(TextBox).
I have a VB.net program that I got from someone else. It is comprised of a main form and 6 other modules (all .vb files). These files all have a "VB" icon next to them in the Explorer pane. I am trying to make a call to a sub-routine in one of the modules from the main form. My line of code is:
QuoteMgr.StartGettingQuotesLevel2(sSym)
where QuoteMgr is the name of the module and StartGettingQuotesLevel2(sSym) is the name of the sub-routine. When I enter this, I get the error message:
Reference to a non-shared member requires an object reference.
The sub-routine is defined in the QuoteMgr Module as follows:
Public Sub StartGettingQuotesLevel2(ByVal oSymbol As String)
What is strange is when I enter:
QuoteMgr.
(the name of the module with a period), it does not show me all the sub-routines and functions in the module. It only shows:
Update_Level1
Update_Level12
Update_Level2
These are Public Const in the module.
Can you tell me what I need to do?
What the compiler is trying to tell you with this error message
Reference to a non-shared member requires an object reference
is that the StartGettingQuotesLevel2 subroutine is an instance method not a shared or class method, see a more detailed explanation here
To call an instance method, you need to have an object instance to call it on. In your case, an object instance of the class type QuoteMgr. Like in the example below:
' create a new QuoteMgr object instance
Dim myQuoteMgr As QuoteMgr = New QuoteMgr()
' call its instance method with "abc" as its oSymbol argument.
myQuoteMgr.StartGettingQuotesLevel2("abc")
It is possible that you only want a single QuoteMgr object instance to be created and used by your main form. In that case, you can make it a member variable of your main form and create it once.
Public Partial Class MainForm
' Create it as a private member variable of the main form
Private m_QuoteMgr As QuoteMgr = New QuoteMgr()
' Use it when "some" button is pressed
Private Sub btnSome_Click(sender As Object, e As EventArgs) Handles btnSome.Click
m_QuoteMgr.StartGettingQuotesLevel2(txtSymbol.Text)
' And possibly do something with the results.
End Sub
End Class
Also, if instances of your QuoteMgr class depend on other object instances for their tasks, you will have to supply these to the constructor method of the QuoteMgr class as the arguments for its constructor's method parameters. Constructors (Sub New(...)) look like this:
Public Class QuoteMgr
' This is a constructor that takes two arguments
' - oMainSymbol: a string value
' - oKernel: an instance of the type Kernel
Public Sub New(oMainSymbol As String, ByRef oKernel As Kernel)
' ....
End Sub
End Class
That means, that when you create a QuoteMgr instance, you have to call its constructor method with the things it need, for example
' There must be an instance of Kernel created somewhere.
Dim myKernel As Kernel = ....
' create a new QuoteMgr object instance with these arguments:
' - oMainSymbol = "SYMABC"
' - oKernel = myKernel
Dim myQuoteMgr As QuoteMgr = New QuoteMgr("SYMABC", myKernel)
Some other recommendations
The explanations I have provided, are about basic VB.NET language features (e.g. the terms highlighted in bold). I suggest that before you make any changes to the code you have, you (1) make a backup of it, and (2) try to read a tutorial and practice on something smaller.
The compiler is (virtually) always right. When it gives you an error message, read it carefully, it will indicate the line where something is wrong and a message that tells you what it needs or is missing.
It is not the purpose of Stack Overflow to provide tutorials or code. It is a Q&A site where the best questions and answers deal with specific, delineated programming problems, for which succinct answers are possible.
Right click your application and go to Properties.
Make sure your application type is "Windows Forms Application".
It means that the routine you are trying to call needs to reference an instance of the form to access the routine. You can either reference an instance as Alex says, or you can make the routine 'Shared', so it doesn't need an instance. To do this, change the definition in QuoteMgr.vb to
Friend Shared Sub StartGettingQuotesLevel2(ByVal oSymbol As String)
Switching it to `Shared' may start showing compiler errors, if the routine accesses form controls or module-level variables. These will need to be added to the parameter list.