Re: Array of class with implicit conversion - C# Discussion Boards

17-Aug-09 11:23

I've probably just been sat in front of this monitor for far too long today (about 14 hours so far Confused | :confused:

) but I can't figure this out!

Consider this struct which is nothing more than an int wrapper:

public struct MyStruct
{
    private int _Value;

    private MyStruct(int value)
    {
        _Value = value;
    }

    public static implicit operator int(MyStruct instance)
    {
        return instance._Value;
    }
    public static implicit operator MyStruct(int value)
    {
        return new MyStruct(value);
    }

    public int Value
    {
        get { return _Value; }
    }
}

I can treat an instance as an int until trying to work with an array or list that expects an int[]:

MyStruct instance0 = 0;
MyStruct instance1 = 1;
MyStruct instance2 = 2;
MyStruct[] myStructArray = new MyStruct[] { instance1, instance2 };
List<int> intList = new List<int>();
intList.Add(instance0);

/* Cannot convert from 'MyStruct[]' to 'System.Collections.Generic.IEnumerable<int>'*/
intList.AddRange(myStructArray);
/* Cannot implicitly convert type 'MyStruct[]' to 'int[]'*/
int[] intArray = myStructArray;

Is there any workaround for this (apart from sleep Laugh | :laugh:

)?

[Addendum] I've just found this blog[^] that says it can be done, but only with reference types [/Addendum]

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
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modified on Monday, August 17, 2009 6:52 PM

Saksida Bojan17-Aug-09 11:32

Saksida Bojan

17-Aug-09 11:32

workaround for first part:

foreach(MyStruct my in myStructArray)
{
intList.Add(my);
}

for the other part i don't know

DaveyM6917-Aug-09 11:37

17-Aug-09 11:37

Yeah, I can iterate through to do it - *~~Buffer.BlockCopy would probably do it without the iteration by me~~, but I figured there was some kind of interface I could implement at the struct level so I could keep the code as is and it would just work.

*[Edit] No it won't, it has to be an array of primitives [/Edit]

Luc Pattyn17-Aug-09 13:08

Luc Pattyn

17-Aug-09 13:08

Hi Dave,

IMO an array of something, say X[] myArray can only hold objects of type X or their derivatives; being implicitly convertible to X doesn't count as such conversion would need code execution to happen.

Smile | :)

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accessing control's value from a seperate class.

PIEBALDconsult17-Aug-09 13:19

PIEBALDconsult

17-Aug-09 13:19

Wait for C# 4.0? (Covariance and contravariance?)

JollyMansArt17-Aug-09 11:07

Re: accessing control's value from a seperate class.

17-Aug-09 11:07

ok I am a little confused.

I have a control textbox and checkbox that I need to read from in a separate class. How do you do this. I just need to read the checked and text values into the class that is not the form.

Saksida Bojan17-Aug-09 11:15

Saksida Bojan

17-Aug-09 11:15

One whay is to make those values static. and then it will be shared among all instance of a form

Re: accessing control's value from a seperate class.

MarkLTX17-Aug-09 11:29

MarkLTX

17-Aug-09 11:29

If the other class has a reference to the form instance, you can either make the two control objects public members of the form class, or add two "get" methods to the form that just return the desired properties of the two control.

Re: accessing control's value from a seperate class.

DaveyM6917-Aug-09 11:32

Re: accessing control's value from a seperate class. [modified] What am I doing wrong?

17-Aug-09 11:32

It depends on the relationship between the class and the form with those controls.

If the form instanciates the class then you can set properties in the class when the controls change.

If the class instanciates the form then the class can read any custom public properties you create on the form, or better still, the form can raise custom events which the class can subscribe to.

If they are only related by a common ancestor, the form can raise events that bubble up to the common ancestor, and that can in turn set a chain of property changes or method calls back down the line to the class.

JollyMansArt17-Aug-09 11:45

Re: accessing control's value from a seperate class. [modified] What am I doing wrong?

17-Aug-09 11:45

Here is what I am trying to do...

This is the code I want to call by 1 procedure retruning a bool value

    private void EnableDisableSaveChanges(String txtboxName, String txtValue)
{
    if (ckbxUniqueName.Checked == true)
    {
        if (HastxtAppNameControlValueChanged & HastxtVerNumberControlValueChanged & HastxtServerLocControlValueChanged & HastxtServerFileNameControlValueChanged & HastxtClientLocFileNameControlValueChanged & HastxtClientFileNameControlValueChanged & HasckbxMasterApplicationControlValueChanged & HasckbxCreateShortcutControlValueChanged & HasckbxUniqueNameControlValueChanged & HasrbtnClientMachineControlValueChanged & HasrbtnClientUserControlValueChanged)
        {
            btnSaveChanges.Enabled = true;
        }
        else
        {
            btnSaveChanges.Enabled = false;
        }
    }
    else
    {
        if (HastxtAppNameControlValueChanged & HastxtVerNumberControlValueChanged & HastxtServerLocControlValueChanged & HastxtServerFileNameControlValueChanged & HastxtClientLocFileNameControlValueChanged & HastxtClientFileNameControlValueChanged & HasckbxMasterApplicationControlValueChanged & HasckbxCreateShortcutControlValueChanged & HasckbxUniqueNameControlValueChanged)
        {
            btnSaveChanges.Enabled = true;
        }
        else
        {
            btnSaveChanges.Enabled = false;
        }
    }

This is the code I want in a seperate class with a main procedure I can call to return a bool value which is above...

#region Validate if a change has occured to any of the fields on tab 1.
////////////////////////////////////
private Boolean HastxtAppNameControlValueChanged()
{
    if (txtAppName.Text == UnchangedAppNameField || txtAppName.Text == null || txtAppName.Text == "")
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HastxtVerNumberControlValueChanged()
{
    if (txtVerNumber.Text == UnchangedAppVersionField || txtVerNumber.Text == null || txtVerNumber.Text == "")
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HastxtServerLocControlValueChanged()
{
    if (txtServerLoc.Text == UnchangedServerPathLocField || txtServerLoc.Text == null || txtServerLoc.Text == "")
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HastxtServerFileNameControlValueChanged()
{
    if (txtServerFileName.Text == UnchangedServerFileNameField || txtServerFileName.Text == null || txtServerFileName.Text == "")
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HastxtClientLocFileNameControlValueChanged()
{
    if (txtClientLoc.Text == UnchangedClientPathLocField || txtClientLoc.Text == null || txtClientLoc.Text == "")
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HastxtClientFileNameControlValueChanged()
{
    if (txtClientFileName.Text == UnchangedClientFileNameField || txtClientFileName.Text == null || txtClientFileName.Text == "")
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HasckbxMasterApplicationControlValueChanged()
{
    if (ckbxMasterApplication.Checked == UnchangedMasterAppField)
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HasckbxCreateShortcutControlValueChanged()
{
    if (ckbxCreateShortcut.Checked == UnchangedCreateShortcut)
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HasckbxUniqueNameControlValueChanged()
{
    if (ckbxUniqueName.Checked == UnchangedUniqueName)
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HasrbtnClientMachineControlValueChanged()
{
    if (rbtnClientMachine.Checked == UnchangedClientMachine)
    {
        return false;
    }
    else
    {
        return true;
    }
}
private Boolean HasrbtnClientUserControlValueChanged()
{
    if (rbtnClientUser.Checked == UnchangedClientUser)
    {
        return false;
    }
    else
    {
        return true;
    }
}
////delete/////



#endregion

modified on Monday, August 17, 2009 6:03 PM

JollyMansArt17-Aug-09 12:07

Re: accessing control's value from a seperate class. [modified] What am I doing wrong?

17-Aug-09 12:07

If i change the methods to static functions I can no longer access the form controls. Please help. I believe at least a static function is what I want but I need to be able to access the forms controls values...)

DaveyM6917-Aug-09 12:20

Re: accessing control's value from a seperate class. [modified] What am I doing wrong? (Simplified...)

17-Aug-09 12:20

You almost never want a static function when dealing with an instance, for obvious reasons.

Strip out all that code and checking a million different properties/fields/controls/whatever - the same principle applies even if there is just one that needs to be checked. It will then be clearer to both us and you!

Unless I missed it somewhere way off screen to the right with all the scrolling, I don't see the relationship between the classes - what instanciates what here?

JollyMansArt17-Aug-09 12:32

Re: accessing control's value from a seperate class. [modified] What am I doing wrong?

17-Aug-09 12:32

Here is what I am trying to do...
I want to be able to receive a response of true or false when these values change.

The Unchanged... is the variable with the current value.
without doing

if (txtAppName.Text == UnchangedAppNameField)
{something...}

I want to have something that says
if (btxtAppName)
{somehting...}

or say (This is the way I would like to do it.)

if (SomeClass.AreThereAnyChanges)
{something}

My main problem is I do not know how to access the forms controls from the class.

Henry Minute17-Aug-09 12:57

Henry Minute

17-Aug-09 12:57

It is too late here for me to make any sense of your problem (my fault, not yours), but your code wouldbe a little shorter and therefore possibly easier to understand if you replace this (and all the ones like it):

private Boolean HasckbxMasterApplicationControlValueChanged()
{
    if (ckbxMasterApplication.Checked == UnchangedMasterAppField)
    {
        return false;
    }
    else
    {
        return true;
    }
}

with:

private Boolean HasckbxMasterApplicationControlValueChanged()
{
    return !(ckbxMasterApplication.Checked == UnchangedMasterAppField);
}

or, of course:

private Boolean HasckbxMasterApplicationControlValueChanged()
{
    return (ckbxMasterApplication.Checked != UnchangedMasterAppField);
}

Henry Minute

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Re: accessing control's value from a seperate class.

Luc Pattyn17-Aug-09 13:13

Luc Pattyn

17-Aug-09 13:13

I agree with Dave and Henry:
- static won't help
- more compact code could make it manageable.

Smile | :)

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Form reload

neha_rai17-Aug-09 9:27

neha_rai

17-Aug-09 9:27

Hi everyone,

What i an trying to do is, call Form1_Load again on say button click in such a way that it resets the form's controls to default values.

Please help by giving your suggestions.

Thanks..!!

kevinnicol17-Aug-09 9:33

kevinnicol

17-Aug-09 9:33

You could always just call Form_Load manualy like a method, passing in null as paramaters. This wouldn't reset your values though unless your Form_Load initializes all the values.

Adam R Harris17-Aug-09 10:20

Adam R Harris

17-Aug-09 10:20

If I were attempting this, I would have a function that would set all the values to their defaults (say initForm) and I would just call that from Form1_Load or anywhere else I wanted to reset the form.

For example;

protected void Form1_Load(){
  initForm();
  ...
}

protected void Button1_Click(object sender, EventArgs args){
  initForm();
  ...
}

private void initForm(){
  Textbox1.text = "[Default Value]";
  Textbox2.text = "[Default Value]";
  ...
}

If at first you don't succeed ... post it on The Code Project and Pray.

Pete O'Hanlon17-Aug-09 10:50

Pete O'Hanlon

17-Aug-09 10:50

I would use binding here. Basically, have your data objects contain the default values and use binding on these objects.

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