C#•2y ago

Double check if an object is one of provided types

Is there a way to quickly check that? I mean a can be either TextBox or CheckBox, doesn't matter which one, I want this condition to success if one of these

44 Replies

?OP•2y ago

void OnLoad(object? sender, EventArgs e)
{
    foreach(var a in Controls)
    {
        if(a is TextBox temp)
        {
            temp.BackColor = Color.Black;
            temp.ForeColor = Color.Silver;
        }
    }
}

void OnLoad(object? sender, EventArgs e)
{
    foreach(var a in Controls)
    {
        if(a is TextBox temp)
        {
            temp.BackColor = Color.Black;
            temp.ForeColor = Color.Silver;
        }
    }
}

Here is where I use it

Angius•2y ago

temp cannot be one of two types Algebraic data types are not a thing in C#

?OP•2y ago

Oh, right!

Angius•2y ago

Or you could maybe do a is { BackColor: _, ForeColor: _ } But that won't allow for a cast either

?OP•2y ago

void OnLoad(object? sender, EventArgs e)
{
    foreach(var a in Controls)
    {
        if(a is TextBox temp )
        {
            temp.BackColor = Color.Black;
            temp.ForeColor = Color.Silver;
        }

        if(a is CheckBox temp1) // will have to copy paste this for each type
        {
            temp1.BackColor = Color.Black;
            temp1.ForeColor = Color.Silver;
        }
    }
}

void OnLoad(object? sender, EventArgs e)
{
    foreach(var a in Controls)
    {
        if(a is TextBox temp )
        {
            temp.BackColor = Color.Black;
            temp.ForeColor = Color.Silver;
        }

        if(a is CheckBox temp1) // will have to copy paste this for each type
        {
            temp1.BackColor = Color.Black;
            temp1.ForeColor = Color.Silver;
        }
    }
}

As I check they don't have any common class that they derive from so I guess I'll have to create an if for each type e.g. if(a is Button temp2) then if(a is MenuItem temp3) and so on...

?OP•2y ago

This doesn't seem to work and this also not

Angius•2y ago

x is {A, B} checks if x is of type that has properties A and B

?OP•2y ago

Yeah but that's going to affect probably entire form as everything here derives from Control class (Windows Forms) I rather wanted to specify to which particular classes I want to compare with

?OP•2y ago

It fails, needs a cast probably

Thinker•2y ago

Just do

if (a is TextBox t)
{
    t.BackColor = Color.Black;
    t.ForeColor = Color.Silver;
}
if (a is CheckBox b)
{
    b.BackColor = Color.Black;
    b.ForeColor = Color.Silver;
}

if (a is TextBox t)
{
    t.BackColor = Color.Black;
    t.ForeColor = Color.Silver;
}
if (a is CheckBox b)
{
    b.BackColor = Color.Black;
    b.ForeColor = Color.Silver;
}

Easiest way without any nonsense

?OP•2y ago

Yeah, this is the only option that comes to my mind but I didn't want that "naive" approach to copy paste bunch of lines that is the same inside each if statement

Thinker•2y ago

You could use a switch

?OP•2y ago

That seemed like a great idea but also fails

?OP•2y ago

I already have it

Thinker•2y ago

Btw, OfType<Control> and not Cast<Control>

?OP•2y ago

What do you mean?

Thinker•2y ago

doesn't even implement IEnumerable??

?OP•2y ago

Yeah, these are the only options probably

Thinker•2y ago

(OfType is slightly better than Cast) Afaik it sometimes fails in weird places because it can't cast OfType also makes sure everything actually is of the type, which is especially relevant with non-generic collections

?OP•2y ago

MODiX•2y ago

thinker227#5176

REPL Result: Success

var xs = new object[] {"a","b","c"};
(xs.Cast<string>(), xs.OfType<string>())

var xs = new object[] {"a","b","c"};
(xs.Cast<string>(), xs.OfType<string>())

Result: ValueTuple<IEnumerable<string>, IEnumerable<string>>

{
  "item1": [
    "a",
    "b",
    "c"
  ],
  "item2": [
    "a",
    "b",
    "c"
  ]
}

{
  "item1": [
    "a",
    "b",
    "c"
  ],
  "item2": [
    "a",
    "b",
    "c"
  ]
}

Compile: 508.973ms | Execution: 35.374ms | React with ❌ to remove this embed.

?OP•2y ago

Uhm... so there is no way to do that?

ero•2y ago

Why not just...

foreach (Control control in Controls)
{

}

foreach (Control control in Controls)
{

}

...? Can't believe no one has suggested this... It's a collection of controls nonetheless

?OP•2y ago

Wow, great, that seems to be really working...

ero•2y ago

It doesn't need to be generic

?OP•2y ago

But I want to distinguish only certain control types that all derive from Control for example TextBox or CheckBox

ero•2y ago

You can then do if (control is TextBox or CheckBox or ...) and do your control.ForeColor anyway

?OP•2y ago

And the original variable has type object @Ero so it is unknown what type it is I tried that and I can't

?OP•2y ago

?OP•2y ago

Hm that's also some solution 🤔 But what if an object is neither of Control type? 😄 The app might crash

?OP•2y ago

Actually that didn't work in my case

ero•2y ago

That's why you specify the type in he loop head

?OP•2y ago

But if I put there Controls I will not use sender variable at all, right?

ero•2y ago

It entirely depends on what you want this event to do Nevermind the fact that this is a pretty bad way to set the styling for controls You should be setting this in a resource dictionary and access the colors from there, at least for xaml based GUI frameworks

?OP•2y ago

Let's say I have 30 text buttons in a form, how do I setup the same back and fore color for them all without doing that one by one?

ero•2y ago

I'm not sure if WinForms has a similar thing By doing it one by one, the correct way

?OP•2y ago

ACiDCA7•2y ago

ive got no clue about winforms but i hope there is a way to use reusable styles, right? right???

ero•2y ago

That way allows you to add theming much easier As in, light and dark themes You bind the colors to a resource, and just change the resource

?OP•2y ago

I think it exists but not for all controls Hmm

thank you all for your help I honestly didn't expect so much attention and how active will become here pepetense

I'll try playing with that, I guess there must be some way 😄

ero•2y ago

But yeah if you're planning on putting this event on multiple controls instead of putting a loop into it, then you don't have many choices i think

?OP•2y ago

I thought about putting an event on the form to execute it after it loads Hmm

to find all controls of a particular type and change their colors

ero•2y ago

if (sender is not (TextBox or CheckBox or Button))
  return;

Control ctrl = (Control)sender;

// ...

if (sender is not (TextBox or CheckBox or Button))
  return;

Control ctrl = (Control)sender;

// ...

Or an array of types, then types.Contains(sender.GetType())... But that's pretty ugly imo...

?OP•2y ago

public ServerProviderForm()
{
    InitializeComponent();

    foreach(var control in Controls.Cast<Control>().Where(x => x is CheckBox or Button or TextBox))
    {
        control.BackColor = Color.Red;
        control.ForeColor = Color.Blue;
    }
}

public ServerProviderForm()
{
    InitializeComponent();

    foreach(var control in Controls.Cast<Control>().Where(x => x is CheckBox or Button or TextBox))
    {
        control.BackColor = Color.Red;
        control.ForeColor = Color.Blue;
    }
}

Aight, so actually that code worked. And I did a mistake by trying to put that in some OnEvent method, the easiest way was to put that in the form constructor method and use Controls property so right after the initialization selected controls of the specified class (CheckBox, Button, TextBox in my example) received Fore and Back color as I specified. Thank you @calledude if I saw correctly that was probably your idea do use .Cast<Control>().Where() Also thank you @Ero#1111@ACiDCA7#8219@thinker227#5176@Angius#1586 I can't ping you because I got timed out I haven't seen such engagement before catpog

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Double check if an object is one of provided types