How To Constrain Generic Parameter To Implement Basic Math Operators
May 27, 2009
Is there a way you can do this ? I would like to have a collection class of T that would be able to do addition, substraction on the T type. I would like to keep T generic instead of having couple collections with the same code, but different types. How would you constrain the generic T?
Example: I would like to define a Collection(of T as IDoMaths). I wouldn't like to create my own integer etc classes with named methods to do the operations, because I think it would be slower. This part of the code is actually called very often and tends to be the bottleneck in performance.
View 2 Replies
ADVERTISEMENT
Mar 24, 2010
I am looking into generics in .NET, and was wondering about the where T : struct constraint. I understand that this allows you to restrict the type used to be a value type. My question is, without any type constraint, you can do a limited number of operations on T. Do you gain the ability to use any additional operations when you specify where T : struct, or is the only value in restricting the types you can pass in?
I guess the question I am actually asking is that if I were to write, (in a discussion about how to use generics), "Now that you have constrained the type argument to value types, you can also do _________ on/with objects of that type", Is there anything to put in that blank? I can think of things for the other constraints, but not this one.
View 3 Replies
Apr 29, 2011
I have to perform calculations dynamically in ASP/VB.NET (Possibly SQL Server). Something like this:
Dim var1, var2 as Integer
Dim Optr as string
var1 = 15
var2 = 25
Optr = +
MyResult(var1, var2, Optr)
And MyResult should equal 40. How can I do this?
View 4 Replies
Sep 16, 2010
Write an overload for every numeric type or if possible constrain a generic extension method to just numeric types.
View 2 Replies
Oct 31, 2011
I need to create a tiny calculator using the basic operators of Addition, Subtraction, Multiplication, and Division. My professor hasn't really covered much of this, so I'm not to sure how to create it.
View 6 Replies
Feb 23, 2012
I've a problem using simple logarithm function Log in some ButtonClick Event. Log is underlined with next warning:System.Diagnostics.Log is not accessible in this context because it is Friend.
Have I missed something or this happens because of the Express version of Visual Basic?
View 1 Replies
Mar 13, 2011
This is just a Translation question. But how do you write a the following C# code in vb.net My problem is that i don't know how to rewrite the this part of the generic T. C# code i want to translate
public static void ShouldEqual<T>(this T actualValue, T expectedValue) {Assert.AreEqual(expectedValue, actualValue); }
[Code]...
View 1 Replies
Feb 17, 2012
I recently installed visual studio 2010 and am using visual basic.The problem I am having is that some operators do not show up within the editor. For example the code line below
test = 3 + 5 - 6 / 7 * 4
only displays
test 3 5 - 6 / 7 * 4
the = + operators are not visible although they are there since the program will work as intended....and if I open up the .vb file in notepad everything is there. It just won't display within Visual Studio.
View 5 Replies
Dec 15, 2010
I'm making a part of my program that takes three inputs from the user and adds them then divides that number by three (the average of the three numbers). [code]...
View 7 Replies
Jul 1, 2010
So im using the inno installer to set up my project and i found a nice script that will check and download 3.5 framework, but can't get it to work for 4.0 so my question is would i be able to compile my project in 3.5 and everything still work correctly?
My program just uses basic math functions and display the data in datagridviews. It uses webbrowser and other toolbox options. It doesn't use the registry and only creates one txt file.
View 1 Replies
Mar 20, 2009
I need another (dozen) pair of eyes on this. The following code:
Interface iRuleEntity
Function GetRuleViolations() As List(Of RuleViolation)
End Interface
Partial Public Class Feedback
[code]....
is giving me this error:'Feedback' must implement 'Function GetRuleViolations() As System.Collections.Generic.List(Of RuleViolation)' for interface 'iRuleEntity'.
View 2 Replies
Mar 3, 2011
I have the following VB.NET function, for example:
Public Function MyFunction (Of TData) (ByVal InParam As Integer) As TData
End Sub
How do I, in a function, determine if TData is a NULLable Type?
View 3 Replies
Jan 18, 2010
how to implement Nullable Parameter of type string in vb.net
Function:
sub savedetail(byval name as string, byval age as integer)
if name isnot nothing then
some work
end if
[code]....
View 1 Replies
Feb 14, 2011
say I have two POCOs I'm using in EF code first
Public class C1
property F1 as integer
End Class
Public class C2
property F2 as String
End Class
I want to have a function that will create a list either of C1 or C2, to be used in some generic operation, such that
[Code]...
View 1 Replies
Jan 23, 2009
I have bee trying to figure out, how to match generic types, without the type parameter in a IF-ELSE statement - heres what i mean:
<P>IF TypeOf(Obj) Is GenericTypeExample(Of ???Any???) Then</P>
<P>End if</P>
View 7 Replies
Feb 21, 2011
Anyone know a good workaround for the lack of an enum generic constraint?[cod]e...
Is is possible to limit the generic type parameter [I don't know if that's the right name] to an Enum?[code]...
View 4 Replies
Jan 26, 2010
In Ironpython site exists references to a language called VBx using DLR. But i can't find any reference to this in google. Where is it?
Edit: Is a Implement of Visual Basic 6.0 in DLR? if yes is so cool. Is more expected for people using VB6 yet and can't migrate because big frameworks.
View 4 Replies
Jun 25, 2010
(Not really sure if I phrased the question correctly...) I want to create a lambda expression that would take an Object, attempt to convert it to a passed-in Type, and print to the console whether it was successful or not. At a glance, the lambda expression may seem a pretty silly way to accomplish this task, but I'd really like to know what I'm doing wrong, so I can better grow my skill set.
VS gives me a designer error about the second "T" in the expression below, telling me it isn't defined) This is where I left off:
[Code]...
View 1 Replies
Jan 29, 2011
Image tagging like facebook in asp.net
how can i implement tagging in my asp.net website using visual basic. how to show older tags or give new tags to any contents. secondly i want to know how to implement cloud tagging?
The say why of tagging this stake overflow is using right now. when we put the mouse on tags text box it suggest some older tags and also we can enter new tags.
View 1 Replies
Mar 5, 2012
well i am having a couple of issues with this particular homework problem and this is my first programming class so there is probably quite a few mistakes well the homework problem is to take three double values entered by a user and display the largest and smallest using math.max and math.min and display the smallest and largest so i thought i could use a listbox and take the values that went to the listbox and assign variables to each so i can try to use each variable in the math.max and min but im not making it to far and i actually might be way off
[Code]...
View 4 Replies
Feb 19, 2010
I am working on a general helper class to sort ListView SubItems. I wrote a base class that has much of the code I need. It includes a MustOverride for the Compare method so that the various inherited classes can implment their own comparisons based upon their type. For the value types, I end up with very similar code such as the following, where x and y are ListViewItems: Public Overloads Overrides Function Compare(ByVal x As Object, ByVal y As Object, ByVal sortColumnIndex As Integer, ByVal sortOrder As System.Windows.Forms.SortOrder) As Integer [code]
View 3 Replies
Feb 18, 2011
I want to use firefox as a default browser for a webbrowser control in a form in Visual Basic Express. How do I do this? How do I launch firefox or an external .exe program from within my application and send a page for it to open or load automatically?
View 4 Replies
Jun 22, 2011
I've just spotted this thread:>> [URL] Here is a C# article on the subject:>> [URL] how to constrain to a ValueType?
I,E:
Public Class ExampleClass(Of T As System.ValueType)
End Class
View 10 Replies
Feb 3, 2012
Consider these two functions[code]...
My question is: what is the right way to accomplish this to resolve the ambiguity so that I can pass value or references types and get overload 2, but pass Functions and get overload 1? Can I constrain the types in some way to make this happen?
View 1 Replies
Sep 5, 2009
How can I constrain the bounds of a rectangle object, which is controlled by a mouse, so it cannot be drawn outside a PictureBox? It is kindof a standard lasso control, the user can click and drag and it will draw a box from the initial click point to the mouse's current location. The starting point is at (rectX,rectY), and the box is drawn to the bottom right using rectDimX and rectDimY (to set the width and height) to see how much of a change has occurred with the mouse. Basically, its what you get with a click and drag on a Windows desktop. The issue here is that the rectangle is able to be drawn outside the PictureBox it is being drawn on, and the next part of the code attempts to reference this location, and then fails with an OutOfMemory exception. This leads me to my second question:
[Code]....
View 1 Replies
Dec 16, 2009
We have migrated our Vb6 application to VB.NET using a third party tool. Now we are in a process of Refactoring and introducing object oriented concepts in the application.
In VB6, we were using structures in many places. As a part of introducing object oriented programming,
1. is it a good idea of changing all Structures to Classes? or Is there a concept of "Generic Structure" similar to Generic collections, Generic classes?
2. Can some one guide me any source containing guide lines or best practices for applications that are migrated to VB.NET from VB6 and implementing object oriented programmaing.
View 3 Replies
Jun 8, 2010
I have a Richtextbox and I would Like the user of the program to be able to drag and drog the richtextbox in other specified places in the program.
I have this very basic
Private blnLifting As Boolean = False
Private Sub richTextBox4_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles RichTextBox4.MouseDown
[Code]....
Firstly its very inaccurate. I want it so the Richtextbox moves with the mouse and not after the mouse. So I want a smooth drag and drog.
So I don't know if this is the wrong code for something that I want perfect like that.
Secondly I dont know if its possible but I would like it so the box can only be dropped in certain area's in my program and if there is a box already occupying that space, It goes back to where it was before.
View 2 Replies
Apr 13, 2012
Consider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
View 2 Replies
Aug 14, 2010
I have a Journal that records entries for different types: Journal(Of ParentT)
[Code]....
View 2 Replies
Nov 25, 2011
I am trying to construct a generic interface class with generic functions. My goal was to use this to implement multiple worker classes for database interaction that have the same basic functionality. Each class will deal with different object for example, category, product or supplier but unless the the functions in the interface are generic that this won't work.This is the interface code that I have but I don't know if I have done it correctly. [code]
View 2 Replies
