Re: Change a property with strings - C# Discussion Boards

softwarejaeger9-Dec-08 22:45

9-Dec-08 22:45

Hello,

i want to change a Property from a class to a specified Value. How can i do this over a function/method like

ChangeValue("MyProperty","Value");

i cannot change them over myClass.myProperty = Value, because everytimes the Property changes.

Many Thanks

Re: Change a property with strings

Mirko19809-Dec-08 22:59

Mirko1980

9-Dec-08 22:59

This can be done using reflection:

// Get the type of terget object
Type myType = myObject.GetType();
// Get the target property info
System.Reflection.PropertyInfo myProperty = myType.GetProperty("MyProperty");
// Set the target value
myProperty.SetValue(myObject, "Value", null);

For reference: MSDN[^]

Re: Change a property with strings

softwarejaeger9-Dec-08 23:37

softwarejaeger

9-Dec-08 23:37

hi,

many thanks, but i got one problem, if i want to change a location, or a color-value or something else like (myObj.Location.x) i get a NullReference-Exception.

So i tried it with

Point myPoint = myObj.Location;
....
System.Reflection.PropertyInfo myProperty = myType.GetProperty("X");
myProperty.SetValue(myObject,20,null);

but of course, the button doesn't change.

How can i solve this Problem?

Re: Change a property with strings

Mirko19809-Dec-08 23:49

Mirko1980

9-Dec-08 23:49

From your code is not clear what is causing the error.
Do the following checks:

- what type represents myType (to work correctly it must be of type Point)?
- the myProperty variable returned by GetProperty has value or is null (if myProperty is null it means that the property "X" does not exist in myType)?
- myObject has value or is null?

Re: Change a property with strings

softwarejaeger10-Dec-08 0:15

softwarejaeger

10-Dec-08 0:15

Ok, just easy Smile | :)

I want to change the Location of a Button. Or maybe the backColor of a Panel, but i can't access this Properties.

If i try it with a code something like this:

Point r = Button1.Location;
// Change the Property "X" of "r"

but then the button doesn't change the location, of course, because i change the value of "r".

Re: Change a property with strings

Mirko198010-Dec-08 0:23

Mirko1980

10-Dec-08 0:23

True, point is a value type Smile | :)

You can always do this:

// Get the type of Location (you can also use typeof(Point))
Type locationType = Button1.Location.GetType();
// Get the X property info
PropertyInfo xProperty = locationType.GetProperty("X");
// Set the target value
xProperty.SetValue(Button1.Location, 10, null);

Re: Change a property with strings

softwarejaeger10-Dec-08 0:59

softwarejaeger

10-Dec-08 0:59

No, it doesn't nothing... =( Exactly copied and pasted...

Re: Change a property with strings

Mirko198010-Dec-08 2:08

Mirko1980

10-Dec-08 2:08

I tried it: actually, the not-reflection property assignment (button1.Location.X = 10;) gives a compiler error "Cannot modify the return value of 'System.Windows.Forms.Control.Location' because it is not a variable".

As always, MSDN[^] has the answer: Because the Point class is a value type (Structure in Visual Basic, struct in Visual C#), it is returned by value, meaning accessing the property returns a copy of the upper-left point of the control. So, adjusting the X or Y properties of the Point returned from this property will not affect the Left, Right, Top, or Bottom property values of the control. To adjust these properties set each property value individually, or set the Location property with a new Point.

Sure you choose a tricky case to practice Reflection Smile | :)

realtime price feed

devvvy9-Dec-08 21:59

devvvy

9-Dec-08 21:59

hello

anyone from financial industry? seen one of those trading/risk application with price updates flickering on screen? well i have seen a number of such apps and I suspect most come with architecture of a frontend gui subscribing for updates from some sort of Price and Position Server/Service. Communication for most part been done in form of sockets with custom implementation or some sort of massaging middleware.

Just a thought, has anyone come across one application where communication is done via remoting or even Web Services? [This is a performance tuning question]

thanks

dev

C# components

Dreekebe9-Dec-08 21:45

Dreekebe

9-Dec-08 21:45

Hi all,

We are just starting out with C# programming. In the past we used Delphi. The first thing we noticed is that there are much less components available. Can anyone advise us where to get/purchase a good package with components? We need at least some way to use USB.

Thanks in advance!
Greetings,
Dreeke

Re: C# components

TJS4u9-Dec-08 22:01

TJS4u

9-Dec-08 22:01

hello

post this question in VIsualStudio forum

Re: C# components

SeMartens9-Dec-08 22:05

SeMartens

9-Dec-08 22:05

Hi Dreeke,

what kind of components do you need? UI Components (e.g. Infragistics) or more sublevel components like Microsoft Enterprise Library.

For USB you could start with this article: http://www.codeproject.com/KB/cs/USB_HID.aspx[^]

Regards
Sebastian

P.S.: I wouldn't say that .NET has missing components, it is just that you have to go on your own and search for them... for example by using google etc.

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

Me in Softwareland.

Re: C# components

Dreekebe9-Dec-08 22:19

Dreekebe

9-Dec-08 22:19

Hi Sebastian,

I have found the USB_HID article just before I read your answer but thanks anyhow. Besides USB we don't miss any components at the moment but we were wondering why there are only a few components available compaired to Delphi. We just want to be one step ahead of the Direction's needs...

I just can't find some list of components. It is hard to search if you don't know how things are named.

Greetings,
Dreeke

Re: C# components

Giorgi Dalakishvili9-Dec-08 22:20

Giorgi Dalakishvili

9-Dec-08 22:20

Here is a component for working with USB: LibUsbDotNet[^]

For UI components I suggest developer express or Telerik.

Giorgi Dalakishvili

#region signature
My Articles

Asynchronous Registry Notification Using Strongly-typed WMI Classes in .NET [^]

My blog
#endregion

Re: C# components

Dreekebe9-Dec-08 22:29

Dreekebe

9-Dec-08 22:29

Hello Giorgi,

That are nice tips! We will investigate them at once. Thanks!

Greetings,
Dreeke

Re: C# components

Tom Deketelaere9-Dec-08 23:05

Tom Deketelaere

9-Dec-08 23:05

There are alot of components out there.

Here is a small list:

Devexpress
Infragistics
Telerik
Component Ace
Syncfusion
Component Factory

There are alot more but this should get you started I think.

On a personal note, I use the devexpress controls and so far no complaints and there support is the best I'v seen.

Re: C# components

Dreekebe9-Dec-08 23:44

Dreekebe

9-Dec-08 23:44

Thanks Tom, this gives me a lot of openings!

Greetings,
Dreeke

List View Scroll Bar

half-life9-Dec-08 21:23

half-life

9-Dec-08 21:23

Hi,

i'd like to know if there's a property to cause the scroll bar in
the listview to always be down,
"autoscroll" Like whenever a new item is added the scroll bar goes with the new item

ant Suggestions??

THANKS Smile | :)

Have Fun
Never forget it

Re: List View Scroll Bar

TJS4u9-Dec-08 21:49

TJS4u

9-Dec-08 21:49

hello

horizontal scroll bar is thr for the list view

use the Expandall(),Collapseall().... properties of the listview to avoid the vertical scroll bar

thanks

Re: List View Scroll Bar

moon_stick9-Dec-08 23:07

moon_stick

9-Dec-08 23:07

Do you mean that you want the list view to automatically scroll to the item you've just added? If so, you need to use the following code:

<br />
    ListViewItem lv = this.listView1.Items.Add(new ListViewItem("new item"));<br />
    lv.Selected = true;<br />
    lv.Focused = true;<br />
    listView1.TopItem = lv;<br />

HTH

It definitely isn't definatley

RadioBoutton as a group

CodingLover9-Dec-08 19:49

CodingLover

9-Dec-08 19:49

Hi all,

I have three radio buttons in a GroupBox. I want to find the selected radio button there. I've done the following.

<br />
int _select;<br />
<br />
if(rb1.Checked)<br />
  _select = 0;<br />

and so on. Seems it's not a good practice at all, say I have 10 radio buttons. Can someone suggest a better way to do this.

Thanks

I appreciate your help all the time...
CodingLover Smile | :)

Re: RadioBoutton as a group

Chintan.Desai9-Dec-08 19:55

Chintan.Desai

9-Dec-08 19:55

use RadioButton class as array and use ".Checked" accordingly with every radionbutton instance in a loop. e.g after creating array instance

if(radioButton[i].Checked)
_select=0;

Thanks,
Chintan(India)

Re: RadioBoutton as a group

N a v a n e e t h9-Dec-08 20:03

N a v a n e e t h

9-Dec-08 20:03

AFAIK, Windows forms don't have a RadioButtonList control. So I think there is no better way than what you are doing.

Navaneeth

How to use google | Ask smart questions

Re: RadioBoutton as a group

CodingLover9-Dec-08 20:28

CodingLover

9-Dec-08 20:28

How about that way that Chintan.Desai talking.

I'll give a try and seems it's working fine.

I appreciate your help all the time...
CodingLover Smile | :)

Re: RadioBoutton as a group

dan!sh 9-Dec-08 20:58

dan!sh

9-Dec-08 20:58

If the radiobuttons are in a groupbox, then use GroupBox.Controls property to loop through.

C isn't that hard: void (*(*f[])())() defines f as an array of unspecified size, of pointers to functions that return pointers to functions that return void

"Always program as if the person who will be maintaining your program is a violent psychopath that knows where you live." - Martin Golding

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