CODEWITHSUNDEEP
c#lambda
CodeCamper
CodeCamper

Reputation: 6980

Pass a variable directly into a Lambda Method?

Is there some way to directly pass in a variable to a lambda method?

For example

string s = "test";
new Thread(() => MessageBox.Show(s)).Start();

Lambda expressions really make life so much easier for me, why does it seem so complicated to pass a variable in from the outside world?

Upvotes: 0

Views: 886

Answers (5)

Dennis
Dennis

Reputation: 37770

How can I accomplish this with 1 semicolon?

What's the problem?

new Thread(() => MessageBox.Show("test")).Start();

Upd.

the easiest way to pass something to lambda is a closures (this is how your question looks). That's why they are so convenient. By passing parameters like shown here, you're destroying all preferences of lambdas. This should be clear for you from your next question about passing two or more parameters.

Using closures, you can do this easily:

// somewhere in the code
var owner = // ...
var text = // ...
var caption = // ...

// here's the closures:
new Thread(() => MessageBox.Show(owner, text, caption)).Start();

Without them you need to get (or make) some type, which will be a container for your parameters, create instance of that type and initialize it members. Indeed, this is the work compiler does for you, when you're using closures. So, why do you prevent the compiler to do all this dirty job?

Upvotes: 1

suresh
suresh

Reputation: 38

Hi for parameterized thread write code like below

string a = "test";
new Thread((s) => { s = "newTest"; }).Start(a);

Upvotes: 1

Atish Kumar Dipongkor
Atish Kumar Dipongkor

Reputation: 10422

Yes, there are many ways to do it. Like

string s = "test";
new Thread((string parameter) => MessageBox.Show(s)).Start();

for more details see ......first 2nd third

Upvotes: 0

aquaraga
aquaraga

Reputation: 4168

It isn't really complicated, especially if you're using the method-group syntax:

new Thread(MessageBox.Show).Start("test");

Upvotes: 2

boniestlawyer
boniestlawyer

Reputation: 707

Lambda expressions can take parameters as follows:

(string s) => MessageBox.Show(s);

This would change the definition of the action, so the method accepting the lambda needs to be able to accept the new delegate.

See the msdn document for further explanation.

Upvotes: 1

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