Passing Items into a sub

[Chris]

Ok, so I have this sub I wrote, and I create a new instance of a
UserControl:

ctrlAPs tempctrl = new ctrlAPs();

Now, I would like to be able to use this sub I wrote for more than one
UserControl, so I was trying to do something like this:

private void somesub(UserControl sourcectrl)
{
sourcectrl tempctrl = new sourcectrl();
}

But when I do that, I get the following error on compile:
"The type or namespace name 'sourcectrl' could not be found (are you
missing a using directive or an assembly reference?)"

So, I'm obviously not passing this in right. There has to be a way to
do this, as I do it with panels and other controls. Any help is
appreciated.

 

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

Ok, so I have this sub I wrote, and I create a new instance of a
UserControl:

sub??? You mean method right?

ctrlAPs tempctrl = new ctrlAPs();

Now, I would like to be able to use this sub I wrote for more than one
UserControl, so I was trying to do something like this:

private void somesub(UserControl sourcectrl)
{
sourcectrl tempctrl = new sourcectrl();
}

But when I do that, I get the following error on compile:
"The type or namespace name 'sourcectrl' could not be found (are you
missing a using directive or an assembly reference?)"

So, I'm obviously not passing this in right. There has to be a way to
do this, as I do it with panels and other controls. Any help is
appreciated.

Why are you creating the UserControl inside the method?
What decide which UserControl to create?
How you return the new instance to the calling code?

What if you create the user control outside and pass it to the method?

 

[Nicholas Paldino [.NET/C# MVP]]

Chris,

You could use Generics, like so:

private void somesub<T>(T sourcectrl) where T : UserControl, new()
{
T tempctrl = new sourcectrl();
}

This will allow you to use the type parameter T and pass in any type
that derives from UserControl as well as has a default, parameterless
constructor.

In the method, you will only be able to call methods that exist on the
UserControl class, nothing that is derived from it.

 

[Marc Gravell]

Based on your example, it looks like generics *might* be the answer,
i.e.

private T somesub<T>() where T : UserControl, new() {
T tempctrl = new T();
// some other code on tempctrl that uses the properties of
UserControl
return tempctrl;
}

The other option is for the caller to create the control locally,
before using your code just to initialize it, in which case you just
need
private void somesub(UserControl control) {
// configure control using the properties of UserControl
}

If not, please clarify what you want to do...

Marc

 

[Chris]

Yeah, I meant method... grr, still stuck in VB6 mode... Anyways, this
is the whole sub I'm working on:

private void test<T>(Panel targetpanel, string sQuery, string
sQueryParamName, string sParamVal, T sourcectrl) where
T:UserControl,new()
{
string Parameter;
conn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=T:\
\RFQMT\\RFQMT Test\\RFQMT Data.mdb;Jet OLEDBatabase
Password=tennis";
OleDbConnection oleconn = new OleDbConnection(conn);
oleconn.Open();

Parameter = txtMemo.Text.ToString();

OleDbCommand cmd = new OleDbCommand(sQuery, oleconn);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.Add(new OleDbParameter(sQueryParamName,
sParamVal));
DataTable dt = new DataTable("APs");

OleDbDataAdapter da = new OleDbDataAdapter(cmd);
da.Fill(ds, "AP");

DataSource = new DataRowCollectionSocket(ds.AP.Rows);


for (int i = 0; i < DataSource.Count; i++)
{
T tempctrl = new UserControl();
//ctrlAPs tempctrl = new ctrlAPs();
pnlAP.Controls.Add(tempctrl);
tempctrl.Top = i * tempctrl.Height - 2;
tempctrl.Left = 0;

foreach (Control c in ctrlAPs1.Controls)
{
Type ctrlType = c.GetType();
ConstructorInfo cInfo =
ctrlType.GetConstructor(Type.EmptyTypes);
Control retControl = (Control)cInfo.Invoke(null);

foreach (Binding ctrlBinding in c.DataBindings)
{
string BindingMember =
ctrlBinding.BindingMemberInfo.BindingMember;
string BindingField =
BindingMember.Substring(BindingMember.LastIndexOf("."));

tempctrl.Controls[c.Name].DataBindings.Clear();

tempctrl.Controls[c.Name].DataBindings.Add(ctrlBinding.PropertyName,
DataSource, BindingField);
}
PropertyInfo DSource =
ctrlType.GetProperty("DataSource");
if (DSource != null)
DSource.SetValue(retControl,
DSource.GetValue(c, null), null);
}
ctrlAPs2.Hide();
}
oleconn.Close();
}

Originally, I had the query and usercontrol information hard coded.
It was a 'continuous form' of sorts, like you'd see in an Access
form. Now I had different usercontrols that acted as different
'forms', but I didn't see any need in making one whole method per
control, which is why I'm trying to pass everything into this one.
Basically it clones the control onto a panel and rebinds the controls
in that panel to a dataset. Now like I said, I could pass in the
panel (i.e. which panel on my form I wanted the control copied to),
but the usercontrol I couldn't. That's why my question is, how to
pass in the control information like I can pass in the panel. HTH

 

[cody]

Chris,

You could use Generics, like so:

private void somesub<T>(T sourcectrl) where T : UserControl, new()
{
T tempctrl = new sourcectrl();
}

This will allow you to use the type parameter T and pass in any type
that derives from UserControl as well as has a default, parameterless
constructor.

In the method, you will only be able to call methods that exist on the
UserControl class, nothing that is derived from it.

You mean

private void somesub<T>() where T : UserControl, new()
{
T tempctrl = new T();
}

 

[Nicholas Paldino [.NET/C# MVP]]

No, I really meant what I typed. I know it doesn't ^do^ anything, but
that's the OP's issue to figure out. I'm assuming the OP has the
prerequisite knowledge to include a return value if needed.

 

[Tom Porterfield]

No, I really meant what I typed. I know it doesn't ^do^ anything, but
that's the OP's issue to figure out. I'm assuming the OP has the
prerequisite knowledge to include a return value if needed.

Look again at the correction that was made as it was not about return
values. You created the local variable from the passed in parameter:

T tempctrl = new sourcectrl();

The correction was to create the local variable from the generic type:

T tempctrl = new T();

If you meant to create the local variable from the passed in parameter
then I'll need some education on how that works especially in instances
where sourcectrl is null.

 

[Nicholas Paldino [.NET/C# MVP]]

Ahh, got it.

 

[Chris]

Thanks folks- Nicholas' suggestion with Marc's / Tom's modification
did the trick!

Ahh, got it.

--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Look again at the correction that was made as it was not about return
values. You created the local variable from the passed in parameter:

T tempctrl = new sourcectrl();

The correction was to create the local variable from the generic type:

T tempctrl = new T();

If you meant to create the local variable from the passed in parameter
then I'll need some education on how that works especially in instances
where sourcectrl is null.