C#•2y ago

How do I pass 1 argument in lambda expression?

string tempTitle = "whatever";

await Task.Run(async (tempTitle) => // here I am having some errors, no idea how to pass this tempTitle variable inside this task to avoid cross-thread exception
{
    Text = "Complete!";
    await Task.Delay(5000);
    Text = tempTitle;
});

string tempTitle = "whatever";

await Task.Run(async (tempTitle) => // here I am having some errors, no idea how to pass this tempTitle variable inside this task to avoid cross-thread exception
{
    Text = "Complete!";
    await Task.Delay(5000);
    Text = tempTitle;
});

Maybe I need to put Action<string> somewhere? Hmm

6 Replies

DaVinki•2y ago

Task.Run doesn't accept an Action<T> But you are able to use tempTitle inside of the function Anonymous functions are able to use variables previously declared in scope but be careful about it

?OP•2y ago

string tempTitle = "something";

await Task.Run(async () =>
{
    Text = "Complete!";
    await Task.Delay(5000);
    Text = tempTitle;
});

string tempTitle = "something";

await Task.Run(async () =>
{
    Text = "Complete!";
    await Task.Delay(5000);
    Text = tempTitle;
});

Is that what you meant? Then I have unhandled exception

DaVinki•2y ago

Is Text a variable you already declared?

?OP•2y ago

No, this is a property of a form, Windows Forms framework

DaVinki•2y ago

So what does the error say?

?OP•2y ago

As on the previous screenshot, Exception Unhandled Cross-thread operation not valid But you gave me something to wonder, it's not an issue with my string but accessing this "Text" property, I need to check if an invoke is required, hold on please

await Task.Run(async () =>
{
    if(InvokeRequired)
    {
        Invoke(TitlePointer, "Complete!");
    }
    else
    {
        TitlePointer("Complete!");
    }

    await Task.Delay(6_000);

    if(InvokeRequired)
    {
        Invoke(TitlePointer, tempTitle);
    }
    else
    {
        TitlePointer(tempTitle);
    }
});

await Task.Run(async () =>
{
    if(InvokeRequired)
    {
        Invoke(TitlePointer, "Complete!");
    }
    else
    {
        TitlePointer("Complete!");
    }

    await Task.Delay(6_000);

    if(InvokeRequired)
    {
        Invoke(TitlePointer, tempTitle);
    }
    else
    {
        TitlePointer(tempTitle);
    }
});

Yeah, that was my mistake and not issue with my string but accessing that "Text" property. Thanks @daVinki a lot! The above script works now and my program runs without cross-thread exception catpog

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How do I pass 1 argument in lambda expression?