Construction - Inherit A Class That Also Has A Constructor
Mar 15, 2010
i'm working with different classes and different constructors. It's working fine until i try to inherit a class that also has a constructor. vb asks for mybase.new but when i add that vb says that a constructor cannot call itself, when i try it in a different way vb asks the parameters of the constructor of the class that i want to inherit.
In the code below I recieve the compile error "Error Too many arguments to 'Public Sub New()'" on the "Dim TestChild As ChildClass = New ChildClass("c")". I do not recieve it on "TestChild.Method1()" even though they are both on the base class I am inheriting from.
Public Class BaseClass Public ReadOnly Text As String Public Sub New(ByVal SetText As String)[code].....
As suggested below but I do not have to do that for Method 1 or other inherited methods and I am looking for the cleanest code possible. This may be a limitation in the system with inheriting parameterized New statements but I can not find it documented anywhere. If it is required then I would like to see the documentation.
I have a base class, "B", which has two constructors, one with no paremeters and the other that accepts one param, an integer. I have a subclass, "S", which inherits from "B" and does not define any constructors in it. I create an instance of S, attempting to pass to the constructor an integer.
I get the error: Error 1 Too many arguments to 'Public Sub New()"
This surprises me because I thought that if a constructor is not defined in the subclass, S, that the base class constructor method, specifically, the one with the single integer param would be invoked w/o an error. why I am getting this error? Are constructors a special case?
I have an abstract class which requires a delegate to function. I pass the delegate into the constructor. Now that I have a non default constructor I need to call the abstract class's constructors from the concrete class which means that I need to use MyBase.New(...). I have included a quick example below.
Public MustInherit Class BaseClass Public Delegate Sub WorkMethod() Private _Work As WorkMethod
[code]....
I have tried to do this but I keep getting the following error: "Implicit reference to object under construction is not valid when calling another constructor".Can I not do what I am trying to do above? I initially had the delegate setup in its own setter method. But then I am creating a deceptive API because it does require a point to a method to work properly.
I have an Object(Class) that consists of a few List Of(T)'s where T is other classes that can be defined by reading lines of a CSV file.I could (I imagine) do the same thing with XML.My question is when does one choose between the two.Are there cases where one is preferred over the other for data storage?
This is another one of my "I think it's not possible but I need confirmation" questions.I have a base class for a bunch of child classes. Right now, this base class has a few common properties the children use, like Name. The base is an abstract class (MustInherit)Technically, this means that everytime a child class is instantiated, it lugs around, in memory, its own copy of Name. The thing is, Name is going to be a fixed value for all instances of a given child. I.e., Child1.Name will return "child_object1", and Child2.Name will return "child_object2".
I have some classes, BsfciFile and StudyFlashCard. Bsfci is the extension to which I save my set of flashcards in an INI format. I am currently working to transform my code from using Windows API calls to access the INI to using a IniFile class that I found on the internet. I would like the BsfciFile to have a Array of StudyFlashCard objects, but I would like the StudyFlashCard class to use the IniFile class object contained in the BsfciFile class. I can pass the IniFile from the BsfciFile class to the constructor for the StudyFlashCard class, but I want it to modify the same IniFile as the BsfciFile class has later on.
I have the following sample code in a VB.NET console application. It compiles and works, but feels like a hack. Is there a way to define EmptyChild so that it inherits from Intermediate(Of T As Class) without using the dummy EmptyClass?
Module Module1 Sub Main() Dim Child1 = New RealChild()[code].....
The other way to do this would be to move the generic code out of the Base class and then create 2 Intermediate classes like this [code]...
Then RealChild would inherit from the generic Intermediate and EmptyChild would inherit from the non-generic Intermediate. My problem with that solution is that the Base class is in a separate assembly and I need to keep the code that handles the generic type in that assembly. And there is functionality in the Intermediate class that does not belong in the assembly with the Base class.
How to create a class which inherits from a data type, specifically from Char data type? I just want to add one property to it. If it's not possible, are there any other ways to accomplish this?
I have problem in Form controls. I inherit label control in a class Mylabel i use this label on my form not standard label control. now i want change the Font all Mylabel in my form then it not change Font when i use standard label control it's work.
I am writing a game editor, and have a lot of different "tool" objects. They all inherit from BTool and have the same constructor. I would like to dynamically populate a toolbox at runtime with buttons that correspond to these tools, and when clicked have them create an instance of that tool and set it as the current tool. Is this possible, and if so will it be better/easier than creating those buttons by hand?
my form displays locations and owners for a same product, the forms have a data grid view that actually takes in the details of the location and owner of that particular product. a product can have multiple owners and locations once its manufactured over time, the forms actually display this all i need is some kind of business logic that can actually manage the historical events of the location and the owner that when a user actually goes in and adds a new entry, the end date of the previous owner gets reduced to one less than the start date of the new owner. this in formation is stored in business layers called the owner collection and the location collection, i am not able to actually inherit or call the location or the owner collection class in the classes.
I am cleaning up some code and I have multiple classes that are 99% exactly the same. So my understanding is that my options are...
1. Create a class and all other classes inherit from it and modify it a bit
2. Create an abstract class and all classes inherit from it and modify a bit ** I took this route
3. Create an interface and all classes Implement that interface.
Here is my 'original' class below (the one that all of them look 99% identical). This class is used in an arraylist so I have a listing of all my images from a folder I have searched.
i've declared a bitmap at class level + i want to load an image into that variable in the constructor. i don't know why but it won't work and everything i've tried won't work either.am i missing a reference or something?
I have an abstract class in vb.net with two subclasses. In the abstract class I have a constuctor that looks like this:[code]I would like to create a second constructor that doesn't take any arguments and just initializes the args to default values.[code]When I attempt to create a new subclass using the second constructor the compiler complains that I'm missing two args to the constructor.Is there a reason I can't overload the constructor in the abstract class?
I have a custom collection class that I would like to pre-populate with data from the database. Basically it would search for "submembers" that are related to the "member" data record using the "member"'s primary key id.
I figured the best way to do this would be in the constructor of the class, but I am not so sure now. The collection class does not have any properties (the member class does).[code]...
I'm making a class that reads a file and processes data in it, but I need some error handling. I'm giving it a constructor that takes a file location and processes that file. How can I make it so the constructor tells the program whether it found the file or not? Optimistically the program that calls this class would check for that first, but since I'm not going to be the only one that uses this class I'd like to know how to secure such a thing. It's probably bad practice to do this within the class, but I'd like to be sure it's as portable as possible.
I discovered that an event raised (directly on indirectly) in the constructor cannot be handled outside the very class. To prove if that was the actual problem, I wrote a simple exemplary app. Class with the event: Namespace Utils Public Class A Public Event Test() Public Sub New() CallTest() [Code] ..... The reason of such behavior became quite obvious after writing those pieces, but maybe there is a way to omit it?
How do I force the Visual Studio compiler to generate an error when a required method is not being called in the constructor of a child class? Like when you edit the form designer code, the compiler complains when InitializeComponent()isn't the first call in the constructor of a form. Is this even possible in VB.NET?
In the past when I have written classes and constructors, I named the variables in the constructor parameter something different than what would have been stored in the actual class itself.What I do now is name them the same, and reference the internal variables with Me.varname.Here is a class I just started building.Is my naming convention incorrect? [code]
I am trying to write some unit tests on a class that looks like this, using Moq [code] the parameterized constructor is private or internal one of the two methods relies on the result of the other.I want to check that when GetThisOrThat is called with a value, it actually calls GetThis. But I also want to mock GetThis so that it returns a specific well-known value.To me this is an example of Partial Mocking, where we create a Mock based on a class, passing the parameters for the constructor. The problem here is that there is no public constructor, and therefore, Moq can not call it..I tried using the Accessors generated by Visual Studio for MSTest, and use those accessors for the mocking, and this is what I came up with [code]