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Say I have custom class foo. I also have a class bar that inherits from foo. I want a method that returns an instance of foo and then want to cast it to bar. How can I do this? I am working with C# 2.0. This is how I imagine it working, and it compiles this way, but I get a runtime error that bar cannot be converted into foo.
public class foo
{
public string someVariable;
}
public class bar : foo
{
public string someotherVariable;
}
public static foo SomeFunction()
{
foo returnVal = new foo();
return foo;
}
public static void AnotherFunction()
{
bar barVar = (bar) SomeFunction();
}
I am almost positive that this can be done, but I can't seem to remember how to do it. I don't want to pass in some kind of reference param or Type.
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You can't cast a foo to a bar when you never created a bar
new foo(); creates a foo not a bar so you can't cast it to a bar.
led mike
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What you've set your code up to do is the ability to cast a bar to a foo; but you can't cast a foo to a bar unless it was already a bar to begin with that you had previously cast as a foo.
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Any ideas of how to do something along these lines? In this scenario, foo holds a bunch of variables used in as results from some operations. I have several super classes that inherit foo that have variables that are specific output for that operation.
As an example, say foo holds a return code and input parameters for calling a Process object. bar has a variable that is assigned later on in the calling method. Another class that also inherits from foo has another unrelated variable that is also set later on by the calling function. Basically, I am trying to write a method that calls the Process object and then returns a base type of foo and then I want to be able to assign the variables that are specific to the superclasses without writing a Convert function.
Seems like there is a fairly easy way to do this, but I keep drawing blanks.
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So inside Foo make a method, lets call it FillFoo(), you make this public and then you can now call it from anything that inherits from Foo. This function however will only fill the values you want to put in Foo. The values for bar and other derived objects can be filled with their own methods contained in their respective objects, such as FillBar(), etc...
I think thats sort of what you are trying to do...
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Yeah, that is basically what I ended up doing. Instead of a method though I made a new protected constructor for foo that takes an instance of foo as a param. I then created a new constructor on bar that takes foo as a param and just pass it down the chain. Kinda silly, but it works. I get why .NET doesn't allow you to do what I was trying originally, but it would be nice if you could cast up the inheritance chain (foo can be cast into bar) as well as down (bar can be cast into foo).
Thanks for pointing me down the right path.
-- modified at 20:24 Tuesday 8th August, 2006
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Can somebody tell me how to change column headers in an asp.net datagrid?
Can I use DataGridTableStyle in asp.net. how can I get my column headers to change programatically?
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What exactly you want to do in datagrid header?
BTW this you better can put in the asp.net forum.
Best Regards,
Apurva Kaushal
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I just wanted to change header names in the datagrid as the user selects certain things from the drop down box. I figured it out today the code is the following:
private void DataGrid1_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
if(e.Item.ItemIndex == -1)
{
e.Item.Cells[0].Text = "Country";
e.Item.Cells[1].Text = "Rate";
e.Item.Cells[2].Text = "NPA code";
e.Item.Cells[3].Text = "Carrier";
e.Item.Cells[7].Text = "less 46%";
}
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if i have table with one col
salary
-------
5
9
7
i want to make comboBox for each record in the database
the probelm now how can make (onchange) even for each comboBox
and save direct to database ...
plz help
Palestine
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Keep your posting in one thread...!!!
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Hey guys,
Could someone tell me how i can get a list of files of a particular type within a directory as well as its subdirectories. I use the Directory.GetFiles Method to get alist of all the files in a location, however, iam having a hard time figuring out to get all the files of particular type from the subdirectories too.
Thanks in advance!
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There's no build in support for recursively searching subdirectories, so you have to do it on your own but that shouldn't be to hard  Use Directory.GetDirectories to get all sub directories and recursively call your search method.
"Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning." - Rick Cook www.troschuetz.de
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Hi,
Create a recursive function which will loop a directory and get a file with specific extension. Call the same function with in the function if the directory has sub directories. Let me know if you need the code for this.
Ram
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I have the labelEdit property of a listview set to true, but only at infrequent, and seemingly random occasions am I actually able to edit the contents of a cell.
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I have a class, IRC, which contains a variable StreamWriter, and a property, Channel, which is associated with the class, ChannelInformation.
ChannelInformation has a function, Join(). How can I call StreamWriter from inside Join() without adding delegates? How does the .NET Framework solve this?
Thanks!  ;P  ![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif) 
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When you say associated with the class ChannelInformation what do you mean by that?
And why not just pass the StreamWriter by reference into Join when you call it?
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if i have table with one col
salary
-------
5
9
7
i want to make comboBox for each record in the database
the probelm now how can make (onchange) even for each comboBox
and save direct to database ...
plz help
Palestine
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I would do it something like this:
Have a foreach statement. Inside that foreach statement create a new combobox. Then add the item to the combobox. You would need to make a method that was generic enough so that you could use it for all of your comboboxes that you make. This method would handle your On Selected Index Change Event.
//thrown together, don't trust it to work without checking it over...
foreach(datarow dr in table[0].rows)
{
ComboBox cb = new ComboBox();
//Make sure you give cb a unique name so that you can tell it apart from the other combos.
cb.items.add("Pass in your value from the datarow here");
cb.WhateverThatChangeSelectedIndexEventIs += ThatEventITalkedAboutUpAbove();
//I'm sure you can manage to place the combobox on the form in a more exact way...
this.controls.add(cb);
}
Should be something like that.
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I created a Forum web application
I have a DAL which implements the Table Data Gateway.
So basically I create the object, get the data, and then close it as fast as possible.
The problem I am facing is I create a new object every time.
I could easily make it static, but then I would face type-safe issues and introduce thread monitoring and what not. So I have elected to make it an instance.
Question: -----
How do I mark these DAL object instances as a pooled object and where or what do I add to the config file to control the specific settings for that pool?
Thanks,
Nick
--------------------------------------------------------
1 line of code equals many bugs. So don't write any!!
My mad coder blog
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What resources does the objects use that makes you want to pool them?
---
b { font-weight: normal; }
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Ista wrote: How do I mark these DAL object instances as a pooled object and where or what do I add to the config file to control the specific settings for that pool?
If you are looking to pool the database connections, just make sure that the connection string is the same every time you open a connection. ADO.NET will take care of the rest.
If you're talking about pooling instances of your custom types, then it's not as simple. There is no out-of-the-box support for object pooling in .NET, but you can use COM+ (via System.EnterpriseServices) to enable object pooling. Check out this[^] section of the sdk for more info about that.
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Friends,
I've a simple form and in its client area, i draw a circle in the OnPaint() method. I also placed few static controls on the form in such a manner that they appear inside the circle.
Now, i want to save this circular region of the client area as a bitmap file. Is it possible ? If yes, then how can i do so ?
Imtiaz
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In the OnPaint, you're grabbing a Graphics object. That Graphics object is for the form. You can actually get a Graphics object on an Image object and paint to there. Then you can save that Image to a file.
Logifusion[^]
If not entertaining, write your Congressman.
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