C# Discussion Boards - CodeProject

Re: calling base-constructor

5-Sep-02 3:41

I would also prefer to be able to delay the base construction. Look at my case.

class MyException: ApplicationException
{
int errorcode;
pubilc MyException() {
errorcode = GetErrorCode();
base ( MyException.GetErrorString(errorcode) );
}
}

Now I wouldnt have to call the GetErrorCode() function everytime when i need to throw it Smile | :)

Maybe there is a way to pre-initialise some variables... Confused | :confused:

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jparsons5-Sep-02 12:19

jparsons

5-Sep-02 12:19

leppie wrote:
Maybe there is a way to pre-initialise some variable

You could use a static constructor to preinitialize some variables.

Jared
jparsons@jparsons.org
www.prism.gatech.edu/~gte477n

Drag and Drop into a node of a treeview

Bill Dean4-Sep-02 11:36

Bill Dean

4-Sep-02 11:36

Hi all,

Does anyone know how to determine which node of a treeview control the mouse pointer is over when a drop occurs? Maybe I am asking the wrong question: I want to allow the user to drag something from a listbox control onto a particular node of a tree view so that the dragged object can be added as a child node.

Any thoughts?

Thanks,
Bill

Re: Drag and Drop into a node of a treeview

Ryan Cromwell5-Sep-02 2:49

Ryan Cromwell

5-Sep-02 2:49

//Gets the point relative to the treeview
Point dragPoint = tv.PointToClient( new Point(e.X, e.Y) );
//Gets the treenode
TreeNode target = tv.GetNodeAt( dragPoint.X, dragPoint.Y );

Re: Drag and Drop into a node of a treeview

Bill Dean5-Sep-02 4:19

Bill Dean

5-Sep-02 4:19

It's always so simple once you know what the answer is. Wink | ;)

Thanks.

Parameters question

leppie4-Sep-02 10:29

4-Sep-02 10:29

I have 3 functions. All 3 the functions are identical except for a type and a function.

Now i want to combined all three into one. I assume it would be,

void CombinedFunction(Type type, SomeHandler function);

No the problem i have is, is that not all of the functions share the same parameters. All 3 have common parameters, but one has 2 extra parameters.

Would i HAVE to overload that function to pass any of the functions as a parameter.

Hope that makes sense Smile | :)

Thanx

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Re: Parameters question

jparsons5-Sep-02 2:59

jparsons

5-Sep-02 2:59

I'm a little bit confused by what you are saying but I believe that you can solve your problem by uses a variable number of arguments.

void CombinedFunction(params object[] args)

Jared
jparsons@jparsons.org
www.prism.gatech.edu/~gte477n

Re: Parameters question

leppie5-Sep-02 3:13

Re: Replace with a C# Regex?

5-Sep-02 3:13

O ya I solved this, noted though far down the optional parameter thread Blush | :O

The easier, better way was just to overload the function as the 2 optional parameters had fixed values when used in that context. Smile | :)

And...the function works beautifully Roll eyes | :rolleyes:

MYrc : A .NET IRC client with C# Plugin Capabilities. See
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Replace with a C# Regex?

Zombies with Coffee, LLC4-Sep-02 9:25

Zombies with Coffee, LLC

4-Sep-02 9:25

I am using regex (regular expressions) in my C# application. I am pulling out the first name like this...

Regex regName = new Regex( @"(?<Last>\S+), (?<First>\S+)" );
Match pMatch  = regName.Match( "Doe, John" );
Text strFirst = pMatch.Groups[ "First" ].Value;

Question: If the user changes the name to 'Jane', how can I use regular expressions to replace the first name?

If strFirst = "Jane", then I want a new string to be "Doe, Jane".

Thanks!!

Eric Gunnerson (msft)4-Sep-02 10:17

Eric Gunnerson (msft)

4-Sep-02 10:17

You'll want to use Regex.Replace, and then create a replacement string. Something like:

Regex regName = new Regex( @"(?<last>S+), (?<first>S+)");

regName.Replace (string, @"\k<last>, Jane");

The \k refers to whatever matched the "Last" capture.

If you're playing with regex, you might like this utility:

http://www.gotdotnet.com/userarea/keywordsrch.aspx?keyword=regular%20expression%20workbench

Clickety

David Stone4-Sep-02 12:20

David Stone

4-Sep-02 12:20

Eric, there's a link tool down at the bottom. Very handy. Just highlight and click link[^]

http://www.gotdotnet.com/userarea/keywordsrch.aspx?keyword=regular%20expression%20workbench [^]

David Stone

But Clinton wasn't a predictable, boring, aging, lying, eloquent, maintainer-of-the-status-quo. He was a predictable, boring-but-trying-to-look-hip, aging-and-fat-but-seemingly-oblivious-to-it, lying-but-in-sadly-blatant-ways, not-eloquent-but-trying-to-make-up-for-it-by-talking-even-more, bringer-in-of-scary-and-potentially-dangerous-new-policies. And there was also Al Gore. It just wasn't *right*.

Shog⁹

Unsafe Question

Nick Parker4-Sep-02 9:24

4-Sep-02 9:24

Is it safe to assume that anytime you do some sort of COM Interop with a dll that wasn't written using the .NET Framework that the method call needs to be prefixed with the unsafe marker, or is this only needed when the method deals with pointers that are outside the bounds of .NET to handle directly?

[System.Runtime.InteropServices.DllImport("kernel32.dll")]
    unsafe int SomeFunction(....);

Nick Parker

Re: Unsafe Question

leppie4-Sep-02 9:39

4-Sep-02 9:39

U only have to specify unsafe if the compiler complains Laugh | :laugh:

No, but really unsafe only needs to be declared if you are using pointer notation in C# ( *, &, ->). It is recommneded though (as far as I am aware) to use the Marshalling class as far as possible, else they wouldnt have called it "unsafe". Smile | :)

Cheers

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Re: Unsafe Question

Nick Parker4-Sep-02 9:43

4-Sep-02 9:43

leppie wrote:
U only have to specify unsafe if the compiler complains

Somehow I believe more people than you think use this method. Smile | :)

Nick Parker

Optional parameters

Nnamdi Onyeyiri4-Sep-02 8:21

Nnamdi Onyeyiri

4-Sep-02 8:21

Is it possible to make a method to have options parameters, without defining the function for each valid configuration?

Suspicious | :suss: Email: theeclypse@hotmail.com URL: http://www.onyeyiri.co.uk
"All programmers are playwrights and all computers are lousy actors."

Nick Parker4-Sep-02 8:56

4-Sep-02 8:56

Not sure, however you could always overload the function. Smile | :)

Nick Parker

leppie4-Sep-02 9:33

4-Sep-02 9:33

Nope

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Nick Parker4-Sep-02 9:44

4-Sep-02 9:44

Why not?

Nick Parker

Eric Gunnerson (msft)4-Sep-02 10:10

Eric Gunnerson (msft)

4-Sep-02 10:10

If you follow the C++ model, the default value is burned into your client-side code, and you can't update it without forcing the user to recompile.

We've talked a bit about whether you could have the compiler automatically generate the overloads that you would write yourself. Would that work for you?

leppie4-Sep-02 10:18

4-Sep-02 10:18

YES

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David Stone4-Sep-02 12:22

David Stone

4-Sep-02 12:22

That would be awesome! Get's my vote...tell Anders that. Big Grin | :-D

David Stone

But Clinton wasn't a predictable, boring, aging, lying, eloquent, maintainer-of-the-status-quo. He was a predictable, boring-but-trying-to-look-hip, aging-and-fat-but-seemingly-oblivious-to-it, lying-but-in-sadly-blatant-ways, not-eloquent-but-trying-to-make-up-for-it-by-talking-even-more, bringer-in-of-scary-and-potentially-dangerous-new-policies. And there was also Al Gore. It just wasn't *right*.

Shog⁹

Paul Riley4-Sep-02 12:21

Paul Riley

4-Sep-02 12:21

Eric Gunnerson (msft) wrote:
We've talked a bit about whether you could have the compiler automatically generate the overloads that you would write yourself. Would that work for you?

OMG | :OMG:

Yes!

You should definitely keep talking about that. This and the lack of (obvious) documentation around Attributes are my two biggest whines about C#/.NET.

There's little more irritating than having a function with 6 optional arguments and having to write 6 one-line overloads which in reality take up 30 lines and give you 6 more paths for testing.

Paul

Nick Parker5-Sep-02 2:59

5-Sep-02 2:59

Nick Parker

leppie4-Sep-02 13:20

4-Sep-02 13:20

You could always rewrite a function like this:

void Function(string name, int size, Color color, params object[] optionalparams){}

Then u have "infinite" overloads, yet alot of work to do.

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