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

🩷🐻 𝙎𝙖𝙘𝙠𝙗𝙤𝙮 🐻🩷•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?

🩷🐻 𝙎𝙖𝙘𝙠𝙗𝙤𝙮 🐻🩷•2y ago

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

DaVinki•2y ago

So what does the error say?

🩷🐻 𝙎𝙖𝙘𝙠𝙗𝙤𝙮 🐻🩷•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?