How can I get Enum description from its value?
I can get the description from the name using:
Public Shared Function GetEnumDescription(ByVal EnumConstant As [Enum]) As String
Dim fi As FieldInfo = EnumConstant.GetType().GetField(EnumConstant.ToString())
Dim attr() As DescriptionAttribute = _
DirectCast(fi.GetCustomAttributes(GetType(DescriptionAttribute), _
False), DescriptionAttribute())
If attr.Length > 0 Then
Return attr(0).Description
Else
Return EnumConstant.ToString()
End If
End Function
But I cant figure out how to pass a variable name to this function. I've tried things like
GetEnumDescription([Enum].GetName(GetType(myEnum), 2)))
but nothing I've tried is correct.
If you have a variable of your enum type, it's simply
GetEnumDescription(myEnum)
Minimal working example:
Enum TestEnum
<Description("Description of Value1")>
Value1
End Enum
Public Sub Main()
Dim myEnum As TestEnum = TestEnum.Value1
Console.WriteLine(GetEnumDescription(myEnum)) ' prints "Description of Value1"
Console.ReadLine()
End Sub
If you have an Integer variable, you need to cast it to your enum type first (CType works as well):
GetEnumDescription(DirectCast(myEnumValue, TestEnum))
Working example:
Enum TestEnum
<Description("Description of Value1")>
Value1 = 1
End Enum
Public Sub Main()
Console.WriteLine(GetEnumDescription(DirectCast(1, TestEnum)))
Console.ReadLine()
End Sub
The source for your confusion seems to be a misunderstanding: Your method does not take the "name" of an enum as a parameter, it takes an Enum as a parameter. That's something different, and it's also the reason why your attempts to use GetName failed.
Here's another solution to get an Enum's description as an extension.
Imports System.ComponentModel
Imports System.Runtime.CompilerServices
<Extension()> Public Function GetEnumDescription(ByVal EnumConstant As [Enum]) As String
Dim attr() As DescriptionAttribute = DirectCast(EnumConstant.GetType().GetField(EnumConstant.ToString()).GetCustomAttributes(GetType(DescriptionAttribute), False), DescriptionAttribute())
Return If(attr.Length > 0, attr(0).Description, EnumConstant.ToString)
End Function
Example use from the previous posts:
Enum Example
<Description("Value1 description.")> Value1 = 1
<Description("Value2 description.")> Value2 = 2
End Enum
Sub Main()
Console.WriteLine(DirectCast(2, Example).GetEnumDescription())
Console.ReadLine()
End Sub
Related
In Turkish Locale, the following seems to be a problem:
Public Enum enFonts
TOKEN_Line_Number = 2
End Enum
Dim StyleName As String = [Enum].GetName(GetType(enFontsUpper), fnt).ToUpper
StyleName is set to "TOKEN_LxNE_NUMBER" where x set to uppercase I with dot on the top. Why?
Here is a test code that demonstrates this behaviour:
Joginder
Module Module1
Public Enum enFonts
TOKEN_Plain_Text = 1
TOKEN_Line_Number = 2
End Enum
Public Enum enFontsUpper
TOKEN_PlaIn_Text = 1
TOKEN_LIne_Number = 2
End Enum
Friend Styles As New Collection
Sub Main()
Dim STL As String = "TOKEN_LINE_NUMBER"
Dim fnt As enFonts = enFonts.TOKEN_Line_Number
'The following compare fails
Call Compare(STL, enFonts.TOKEN_Line_Number)
' The following compare works because In changed i to uppercase I in LIne
Call Compare2(STL, enFontsUpper.TOKEN_LIne_Number)
End Sub
Private Sub Compare(STL As String, fnt As enFonts)
Dim StyleName As String = [Enum].GetName(GetType(enFonts), fnt).ToUpper
If StyleName.Equals(STL) Then
Call MsgBox(String.Format("'{0}' is equal to '{1}'", STL, StyleName))
Else
Call MsgBox(String.Format("'{0}' is NOT equal to '{1}'", STL, StyleName))
End If
End Sub
Private Sub Compare2(STL As String, fnt As enFontsUpper)
Dim StyleName As String = [Enum].GetName(GetType(enFontsUpper), fnt).ToUpper
If StyleName.Equals(STL) Then
Call MsgBox(String.Format("'{0}' is equal to '{1}'", STL, StyleName))
Else
Call MsgBox(String.Format("'{0}' is NOT equal to '{1}'", STL, StyleName))
End If
End Sub
End Module
I have now discovered that the problem is with ToUpper in Turkish locale. "i".ToUpper returns capital I with dot on the top. There seem to many solutions in Stackoverflow for this problem. Simple solution is to use ToLower instead of `ToUpper.
I am trying to reference the name of a variable as a string. I have a list of global variables
Public gvHeight As String = Blank
Public gvWeight As String = Blank
Public gvAge As String = Blank
I need to reference the name of the variables for an external API call. I am trying to avoid specific code per variable, instead allow me to add a new variable and everything reference correctly. I already have the rest of the code to deal with the name as a string.
example:
public Height as string
public weight as string
public age as string
[elsewhere in code]
for each var as string in {public variables}
CallToAPI(var.name) 'needs to send "height" "weight" or "age" but there are a lot so hardcoding is not a good solution
edited for example
You need to find the public fields through Reflection.
Having an example dll compiled from this source-code:
Public Class Class1
Public Field1 As String = "value 1"
Public Field2 As String = "value 2"
Public Field3 As Integer
End Class
Then you could do this:
' The library path.
Dim libpath As String = "...\ClassLibrary1.dll"
' The assembly.
Dim ass As Assembly = Assembly.LoadFile(libpath)
' The Class1 type. (full namespace is required)
Dim t As Type = ass.GetType("ClassLibrary1.Class1", throwOnError:=True)
' The public String fields in Class1.
Dim strFields As FieldInfo() =
(From f As FieldInfo In t.GetFields(BindingFlags.Instance Or BindingFlags.Public)
Where f.FieldType Is GetType(String)
).ToArray
' A simple iteration over the fields to print their names.
For Each field As FieldInfo In strFields
Console.WriteLine(field.Name)
Next strField
If all your variables are of the same type (here strings), you can use a Dictionary...
Public MyModule
Private myVars As Dictionary(Of String, String)
Public Function CallToAPI(VarName As String) As String
If myVars.ContainsKey(VarName) Then
Return myVars(VarName)
End If
Return ""
End Function
End Module
And somewhere else in your external code
Module TestModule
Public Sub Test()
Dim myVar = MyModule.CallToAPI("test")
End Sub
End Module
Now if your variables aren't the same, then you must use Reflection... and that's where the fun begins...
Is it possible to return a value from enum with a string index? For example I can use:
Enum test
firstval
secondval
thirdval
End Enum
Dim index As Integer = 1
CType(index, test).ToString()
to return firstval but is there a way to do something similar where index is a string value? For example:
Enum test
firstval = "one"
secondval = "two"
thirdval = "three"
End Enum
Dim index As string = "one"
CType(index, test).ToString()
It's not possible using an Enum, but you could easily create a type that can do what you want, using the Narrowing operator.
simple example:
Class Test
Private Shared _lookup As Dictionary(Of String, Test)
Private Key As String
Private Name As String
Public Shared ReadOnly firstval As Test = New Test("one", "firstval")
Public Shared ReadOnly secondval As Test = New Test("two", "secondval")
Public Shared ReadOnly thirdval As Test = New Test("three", "thirdval")
Private Sub New(key As String, name As String)
Me.Key = key
Me.Name = name
If _lookup Is Nothing Then _
_lookup = New Dictionary(Of String, Test)
_lookup.Add(key, Me)
End Sub
Public Overrides Function ToString() As String
Return Me.Name ' or whatever you want '
End Function
Public Shared Widening Operator CType(obj As Test) As String
Return obj.Key
End Operator
Public Shared Narrowing Operator CType(key As String) As Test
Return _lookup(key)
End Operator
End Class
usage:
Dim index As string = "one"
' returns firstval '
CType(index, Test).ToString()
There are several other alternatives.
One is to get the names used in the enum. For instance:
Friend Enum ImgFormat
Bitmap
GIF
JPeg
TIFF
PNG
End Enum
Dim ImgNames() As String
...
ImgNames = [Enum].GetNames(GetType(ImgFormat))
If your names are not friendly enough, decorate them with Descriptions:
Imports System.ComponentModel
Friend Enum ImgFormat
<Description("Bitmap (BMP)")> Bitmap
<Description("Graphic Interchange (GIF)")> GIF
<Description("Jpg/JPeg (JPG)")> JPeg
<Description("Tagged Image (TIFF)")> TIFF
<Description("Portable Graphics (PNG)")> PNG
End Enum
To get the descriptions, requires reflection which gets involved:
Imports System.Reflection
Imports System.ComponentModel
Public Class EnumConverter
' gets a single enum description
Public Shared Function GetEnumDescription(ByVal EnumConstant As [Enum]) As String
Dim fi As FieldInfo = EnumConstant.GetType().GetField(EnumConstant.ToString())
Dim attr() As DescriptionAttribute = _
DirectCast( _
fi.GetCustomAttributes(GetType(DescriptionAttribute), False), _
DescriptionAttribute() )
If attr.Length > 0 Then
Return attr(0).Description
Else
Return EnumConstant.ToString()
End If
End Function
' get all the enum descriptions:
Public Shared Function GetEnumDescriptions(ByVal type As Type) As String()
Dim n As Integer = 0
Dim enumValues As Array = [Enum].GetValues(type)
Dim Descr(enumValues.Length - 1) As String
For Each value As [Enum] In enumValues
Descr(n) = GetEnumDescription(value)
n += 1
Next
Return Descr
End Function
End Class
To use:
Dim ImgNames() As String = EnumConverter.GetEnumDescriptions(ImgFormat)
ImgNames(ImgFormat.GIF) would be 'Graphic Interchange (GIF)'
This will break if the Enum values are not the default 0, 1, 2 ... IF that is an issue (and it really is), then build a class around it to store the Name or Description with the Enum Value. Rather than building a class to create a pseudo enum, make one to create a list of name-value pairs consisting of the Descriptions and Enum Value.
I have a problem with getting variable from another class and cannot understand what to do with interface`s functions which have already existed in another class.
What I have:
Form where clicking on a button I should see reversed string:
(I want to call pooraja.StringReverse which is below)
Private Sub btnPoora1_Click(sender As System.Object, e As System.EventArgs) _
Handles btnPoora1.Click
'Dim text As PrjTekstiPooraja.ITeisendused = New PrjTekstiPooraja.CtekstiPooraja
Dim text As PrjTekstiPooraja.ITeisendused = New PrjTekstiPooraja.CtekstiPooraja
Dim pooraja As PrjTekstiPooraja.ITeisendused = New PrjTekstiPooraja.CAlgrotimilinePooraja
text.strText = txtSisendTekst.Text
txtValjundTekst1.Text = pooraja.stringReverse
text.intStart = 1
text.intEnd = Len(txtSisendTekst.Text)
ascFSymbol.Text = text.ascFirstSymbol
ascLSymbol.Text = text.ascLastSymbol()
End Sub
CtekstiPooraja:
(Thiss class will be used to store data.Under data I mean strPooratavText. Data will be used in CAlgoritmilinePooraja)
Public Class CtekstiPooraja
Implements ITeisendused
Public intStartSymbol As Integer
Public intEndSymbol As Integer
Public strPooratavText As String
Private Property intEnd As Integer Implements ITeisendused.intEnd
Get
Return intEndSymbol
End Get
Set(ByVal value As Integer)
intEndSymbol = value
End Set
End Property
Private Property intStart As Integer Implements ITeisendused.intStart
Get
Return intStartSymbol
End Get
Set(ByVal value As Integer)
intStartSymbol = value
End Set
End Property
Public Function pooraText() As String Implements ITeisendused.pooraText
Return StrReverse(strPooratavText)
End Function
Public Property strText As String Implements ITeisendused.strText
Get
Return strPooratavText
End Get
Set(ByVal value As String)
strPooratavText = value
MsgBox(strPooratavText)
End Set
End Property
Public Sub teisendaText(ByRef strSisendText As String) Implements ITeisendused.teisendaText
strPooratavText = StrReverse(strSisendText)
End Sub
Public Function ascFirstSymbol() As String Implements ITeisendused.ascFirstSymbol
Return Asc(GetChar(strPooratavText, intStartSymbol))
End Function
Public Function ascLastSymbol() As String Implements ITeisendused.ascLastSymbol
Return Asc(GetChar(strPooratavText, intEndSymbol))
End Function
Public Function stringReverse() As String Implements ITeisendused.stringReverse
Return Nothing
End Function
End Class
CAlgrotimilinePooraja:
(This class will be called by form button. There I need to use stringReverse function with data from CtekstiPooraja. The problem is that everywhere is used the same interface and there is some functions and procedures from this interface which isnt necessary. I dont know what value should return these unused functions/procedures. Just using "return Nothing or return 0/ "" is bad idea, may be there is possible somehow referenceto to CTekstiPooraja functions/procedures variables")
Public Class CAlgrotimilinePooraja
Implements ITeisendused
Private x As New PrjTekstiPooraja.CtekstiPooraja
Public Function stringReverse() As String Implements ITeisendused.stringReverse
MsgBox(x.strPooratavText)
Dim i As Integer = 0
Dim j As Integer
Dim characters(j) As Char
Dim newString(j) As Char
characters = x.strPooratavText.ToCharArray()
newString = x.strPooratavText.ToCharArray()
Do While i <= j - 1
newString(i) = characters(j - 1)
newString(j - 1) = characters(i)
i += 1
j -= 1
Loop
Return newString
End Function
Public Function ascFirstSymbol() As String Implements ITeisendused.ascFirstSymbol
Return x.ascFirstSymbol()
End Function
Public Function ascLastSymbol() As String Implements ITeisendused.ascLastSymbol
Return Nothing
End Function
Public Property intEnd As Integer Implements ITeisendused.intEnd
Get
Return x.intEndSymbol
End Get
Set(ByVal value As Integer)
End Set
End Property
Public Property intStart As Integer Implements ITeisendused.intStart
Get
Return x.intStartSymbol
End Get
Set(ByVal value As Integer)
End Set
End Property
Public Function pooraText() As String Implements ITeisendused.pooraText
Return x.pooraText()
End Function
Public Property strText As String Implements ITeisendused.strText
Get
Return x.strPooratavText
End Get
Set(ByVal value As String)
End Set
End Property
Public Sub teisendaText(ByRef strSisendText As String) Implements ITeisendused.teisendaText
x.strPooratavText = StrReverse(strSisendText)
End Sub
End Class
MyInterface:
Public Interface ITeisendused
Property intStart As Integer
Property intEnd As Integer
Property strText As String
Function pooraText() As String
Function ascFirstSymbol() As String
Function ascLastSymbol() As String
Function stringReverse() As String
Sub teisendaText(ByRef strSisendText As String)
End Interface
I cannot understand how to get variable strPooratavText from CTekstiPooraja to CAlgrotimilinePooraja. Usually that instancewhich I create worked but not now. And I cannot understand what to do with already existed function and procedures in CAlgoritmilinePooraja when the same function and procedures has in another class. Maybe, it is possible to reference them somehow to existed functions/procedures in CTekstiPooraja? Could you explain me how to id, already tired to surf Internet to find a solution for it, have already try a lot.
Well, I think you have a fundamental problem with understanding interfaces. They describe data and behavior, it should be extremely rare to want to implement part of an interface.
That said, if you do want to implement part of an interface, instead of returning bogus data, throw an exception for behavior you don't implement.
Your specific problem is that CAlgoritmilinePooraja works on an instance of CtekstiPooraja, but it creates a new instance instead of using an existing one. Add
Sub New(incomingX as CtekstiPooraja)
x = incomingX
End Sub
to CAlgoritmilinePooraja. And then in your event, use....
Dim text As PrjTekstiPooraja.CtekstiPooraja = New PrjTekstiPooraja.CtekstiPooraja
text.strText = txtSisendTekst.Text
Dim pooraja As PrjTekstiPooraja.ITeisendused = New PrjTekstiPooraja.CAlgrotimilinePooraja(text)
That is the minimum change to your design that gets what you want to happen to happen but it's problably not what you should do. Other than implementing strReverse, CtekstiPooraja seems to be what you want, CAlgrotimilinePooraja looks to do just one thing, the actual string reversal.
I would move the implementation of strReverse into CtekstiPooraja, and then eliminate CAlgrotimilinePooraja.
PS I would try to stick to English for class names as well as functions and variables.
How can I get the name of the object that was passed byref into a method?
Example:
Dim myobject as object
sub mymethod(byref o as object)
debug.print(o.[RealName!!!!])
end sub
sub main()
mymethod(myobject)
'outputs "myobject" NOT "o"
end sub
I'm using this for logging. I use one method multiple times and it would be nice to log the name of the variable that I passed to it. Since I'm passing it byref, I should be able to get this name, right?
For minitech who provided the answer:
This would give you the parameter name in the method and it's type, but not the name of the variable that was passed byref.
using system.reflection
Dim mb As MethodBase = MethodInfo.GetCurrentMethod()
For Each pi As ParameterInfo In mb.GetParameters()
Debug.Print("Parameter: Type={0}, Name={1}", pi.ParameterType, pi.Name)
Next
If you put that in "mymethod" above you'd get "o" and "Object".
That's impossible. Names of variables are not stored in IL, only names of class members or namespace classes. Passing it by reference makes absolutely zero difference. You wouldn't even be able to get it to print out "o".
Besides, why would you ever want to do that?
Alternatively you could get the 'Type' of the object using reflection.
Example: (Use LinqPad to execute)
Sub Main
Dim myDate As DateTime = DateTime.Now
MyMethod(myDate)
Dim something As New Something
MyMethod(something)
End Sub
Public Class Something
Public Sub New
Me.MyProperty = "Hello"
End Sub
Public Property MyProperty As String
End Class
Sub MyMethod(Byref o As Object)
o.GetType().Name.Dump()
End Sub
Sorry to say, but this is your solution. I left (ByVal o As Object) in the method signature in case you're doing more with it.
Sub MyMethod(ByVal o As Object, ByVal name As String)
Debug.Print(name)
End Sub
Sub Main()
MyMethod(MyObject, "MyObject")
End Sub
Alternatively you could create an interface, but this would only allow you to use MyMethod with classes you design. You can probably do more to improve it, but as this code stands you can only set the RealName at creation.
Interface INamedObject
Public ReadOnly Property RealName As String
End Interface
Class MyClass
Implements INamedObject
Public Sub New(ByVal RealName As String)
_RealName = RealName
End Sub
Private ReadOnly Property RealName As String Implements INamedObject.RealName
Get
Return _RealName
End Get
End Property
Private _RealName As String
End Class
Module Main
Sub MyMethod(ByVal o As INamedObject)
Debug.Print(o.RealName)
End Sub
Sub Main()
Dim MyObject As New MyClass("MyObject")
MyMethod(MyObject)
End Sub
End Module
If your program is still in the same place relative to the code that made it, this may work:
' First get the Stack Trace, depth is how far up the calling tree you want to go
Dim stackTrace As String = Environment.StackTrace
Dim depth As Integer = 4
' Next parse out the location of the code
Dim delim As Char() = {vbCr, vbLf}
Dim traceLine As String() = stackTrace.Split(delim, StringSplitOptions.RemoveEmptyEntries)
Dim filePath As String = Regex.Replace(traceLine(depth), "^[^)]+\) in ", "")
filePath = Regex.Replace(filePath, ":line [0-9]+$", "")
Dim lineNumber As String = Regex.Replace(traceLine(depth), "^.*:line ", "")
' Now read the file
Dim program As String = __.GetStringFromFile(filePath, "")
' Next parse out the line from the class file
Dim codeLine As String() = program.Split(delim)
Dim originLine As String = codeLine(lineNumber * 2 - 2)
' Now get the name of the method doing the calling, it will be one level shallower
Dim methodLine As String = Regex.Replace(traceLine(depth - 1), "^ at ", "")
Dim methodName = Regex.Replace(methodLine, "\(.*\).*$", "")
methodName = Regex.Replace(methodName, "^.*\.", "")
' And parse out the variables from the method
Dim variables As String = Regex.Replace(originLine, "^.*" & methodName & "\(", "")
variables = Regex.Replace(variables, "\).*$", "")
You control the depth that this digs into the stack trace with the depth parameter. 4 works for my needs. You might need to use a 1 2 or 3.
This is the apparently how Visual Basic controls handle the problem.
They have a base control class that in addition to any other common properties these controls may have has a name property.
For Example:
Public MustInherit Class NamedBase
Public name As String
End Class
Public Class MyNamedType
Inherits NamedBase
public Value1 as string
public Value2 as Integer
End Class
dim x as New MyNamedType
x.name = "x"
x.Value1 = "Hello, This variable is name 'x'."
x.Value2 = 75
MySubroutine(x)
public sub MySubroutine(y as MyNamedType)
debug.print("My variable's name is: " & y.name)
end sub
The output in the intermediate window should be:
My variable's name is: x