Re: Argument - C# Discussion Boards

Buy a basic book on OO and read it. Then move on to C#. Of course you can't assign a value of a different type to the type of the object. You CAN derive from EventArgs for your own events, and add properties, but you can't change the class for a framework event, or turn an EventArgs into a number or string.

Christian Graus

Driven to the arms of OSX by Vista.

"I am new to programming world. I have been learning c# for about past four weeks. I am quite acquainted with the fundamentals of c#. Now I have to work on a project which converts given flat files to XML using the XML serialization method" - SK64 ( but the forums have stuff like this posted every day )

shennwooi wrote:
EventArgs e = null;

This appears to work. but why would you want to do that? what is your requirement?

shennwooi wrote:
Can i assign some string or integer to EventArgs?

No. You cant do that. Again why would you want to?

Life goes very fast. Tomorrow, today is already yesterday.

musefan wrote:
shennwooi wrote:
EventArgs e = null;
This appears to work.

Had you doubts about? Big Grin | :-D

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

yeah i wanted to double check it was nullable. Like i have said i dont see a use for it...

Life goes very fast. Tomorrow, today is already yesterday.

A object reference is, by definition, nullable.

musefan wrote:
Like i have said i dont see a use for it...

I see.

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

what would you use it for?

Life goes very fast. Tomorrow, today is already yesterday.

Like for any other object reference: a null value simply states that the reference 'points' to no object.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

yes, im not doubting the use of it for other object types. but why would anyone need to assign null to EventArgs instance?

Life goes very fast. Tomorrow, today is already yesterday.

Probably noone. Neverthless, the wise developer receiving a EventArgs reference (in the event handler), should consider the possibility of a null value.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

well EventArgs does not have any useful information so you wouldn't need to check if its null or not as you would never use the reference.

Unless of course you pass it another EventArgs derived object but then you will need a cast so you would validate it first then.

Life goes very fast. Tomorrow, today is already yesterday.

Sometimes, for example (admittedly a bad one) if you want to call a button click handler, you can use myButton_Click(this, null), rather than myButton.PerformClick(). Although, as you have said, why would you want to?

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

yep, that possible. But if you were testing with null then your button click handler would surely never make use of EventArgs and you would never need to check it.

anyway if you want the functionality called manually then you should have it as a separate function that the button click handler also calls.

Life goes very fast. Tomorrow, today is already yesterday.

Agreed, but since EventArgs is essentially empty, nothing that I can think of actually makes any use of it.

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

musefan wrote:
well EventArgs does not have any useful information so you wouldn't need to check if its null or not as you would never use the reference

One useful information, maybe, for instance, if EventArgs reference is null or not. Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

do you mean you could use it to represent a boolean value for something else such as 'isUserClick'?

Life goes very fast. Tomorrow, today is already yesterday.

Yes, it may represent a boolean value, ugly, I should admit.
Smile | :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

yes very ugly, but i guess that is an answer to my question of what it could be used for so good answer.

Life goes very fast. Tomorrow, today is already yesterday.

i'm doing vsts2008 unit testing. How m i assign date to following test method?

public void btnAddEntry_ClickTest()
{
frmMileage_Accessor target = new frmMileage_Accessor(); // TODO: Initialize to an appropriate value
object sender = null; // TODO: Initialize to an appropriate value
EventArgs e = null; // TODO: Initialize to an appropriate value
target.btnAddEntry_Click(sender, e);
//Assert.Inconclusive("A method that does not return a value cannot be verified.");
}

as a parameter, no?

Life goes very fast. Tomorrow, today is already yesterday.

yes.wan to know how to assign a value to test method.

perhaps try creating your own eventargs class that inherits from EventArgs then you can put any properties you want to use in it and pass that to the button click handler

Life goes very fast. Tomorrow, today is already yesterday.

Yes you can assign null to EventArgs, but not string or integer. Best way would be to derive EventArgs.

Have a look here:

http://msdn.microsoft.com/en-us/library/system.eventargs.aspx[^]

Regards
Sebastian

It's not a bug, it's a feature!

Check out my CodeProject article Permission-by-aspect.

Me in Softwareland.

shennwooi wrote:
Can i assign some string or integer to EventArgs?

NO.

If there is a good reason for doing this, create your own class which derives from EventArgs. Use implicit operator. Eg:

class MyEventArgs : EventArgs
{
    string name;
    public string Name { get { return name; } }

    public MyEventArgs(string name)
    {
        this.name = name;
    }

    public static implicit operator MyEventArgs(string str)
    {
        return new MyEventArgs(str);
    }
}

class Program
{
    static void Main(string[] args)
    {
        MyEventArgs ar = "hello";
        Console.WriteLine(ar.Name);
    }
}

Navaneeth

How to use google | Ask smart questions

use this

btnTest_Click(this, null);

to test button click.

*12Code

what if i wan to test the following function?

private void btnAddEntry_Click(object sender, EventArgs e)
{
double gas, miles;
int i;
string d;
char c;
bool validDate;
// Validate date format (actual values not checked)
// strip out any spaces
d = "";
for (i = 0; i < txtDate.Text.Length; i++)
{
if (txtDate.Text.Substring(i, 1) != " ")
{
d += txtDate.Text.Substring(i, 1);
}
}
txtDate.Text = d;
validDate = true;
// make sure date has eight characters (two are slashes remainder are numbers)
if (txtDate.Text.Length != 8)
{
validDate = false;
}
else
{
for (i = 0; i < 8; i++)
{
c = Convert.ToChar(txtDate.Text.Substring(i, 1));
if (i == 2 || i == 5)
{
if (c != '/')
{
validDate = false;
}
}
else
{
if (c < '0' || c > '9')
{
validDate = false;
}
}
}
}
if (!validDate)
{
MessageBox.Show("Date must be in form mm/dd/yy", "Date Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
txtDate.Focus();
return;
}
// Make sure miles is greater than previous value
miles = Convert.ToDouble(txtMiles.Text);
if (numValues > 0)
{
if (miles <= odometer[numValues - 1])
{
MessageBox.Show("Odometer reading less than previous value.", "Odometer Reading Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
txtMiles.Focus();
return;
}
}
// No zero gallons allowed
gas = Convert.ToDouble(txtGallons.Text);
if (gas <= 0)
{
MessageBox.Show("Gallons pumped must be greater than zero", "Gallons Pumped Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
txtGallons.Focus();
return;
}
dates[numValues] = txtDate.Text;
odometer[numValues] = miles;
gallons[numValues] = gas;
numValues++;
NewEntryLine();
txtDate.Text = GetToday();
txtMiles.Text = "";
txtGallons.Text = "";
txtDate.Focus();
}