Argument

[CPallini]

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

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
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[BabyOreo]

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

[musefan]

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.

[CPallini]

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

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]

[musefan]

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.

[Henry Minute]

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.”

[musefan]

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.

[musefan]

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.

[Henry Minute]

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.”

[Luc Pattyn]

Hi, split your code into two methods: 1. one contains the "bunsiness logic" and no GUI stuff (No MessageBox); it does not take sender or eventargs as parameters, and it does return a calculated value and outputs (through out parameter) a string which should be shown to the user. 2. the buttonClickHandler which mainly calls the other method and shows the MessageBox when there is a need to.

private void btnAddEntry_Click(object sender, EventArgs e) {
string s;
double result=calculate(out s);
if (s==null) textBox.Text="The result is "+result;
else MessageBox.Show(s);
}

private double calculate(out string message) {
message=null;
double result=...;
if (...) message="Something went wrong";
...
return result;
}

That way you can easily perform unit tests on the business logic, and there probably won't be a need to test the actual buttonClickHandler anymore. :)

Luc Pattyn [Forum Guidelines] [My Articles]

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[CPallini]

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. :)

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]

[musefan]

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.

[CPallini]

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

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]

[musefan]

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.