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‫Welcome back.

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‫In this lecture, you will learn about anonymous methods.

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‫An anonymous method is a method without a name.

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‫Well, who gets it?

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‫And anonymous methods in C sharp can be defined using the delegate keyword and can be assigned to a

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‫variable of the delegate type.

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‫This means we don't have to define a method of our own each time we want to call a method that needs

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‫a delegate, since maybe we want to call it once.

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‫So defining a dedicated delegate every time we need one can ruin the code structure very fast.

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‫So adding to our previous example, where we created a bunch of filters, you might recall that here

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‫is adult, is senior and all of the good stuff.

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‫And now let's go ahead and create two additional filters where we create a custom Boolean expression

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‫as our filter and a second filter where we simply display all the entries in our list.

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‫So let's go ahead and go to our main method where we displayed all of the people, right?

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‫We call this method here and now let's create a new filter delegate.

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‫So I'm just going to use the filter delegate keyword, the one that we have set up here at the top.

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‫And you will see that it needs to return a boolean and it needs to have a person as the parameter.

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‫So let's call it filter.

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‫And here we need to use the delegate keyword once again and then we can use the parameters that we need

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‫to pass.

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‫And you can see it's still complaining because first of all, we need to add a semicolon here to bottom

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‫and then we need to make sure that we return a value.

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‫Of type boolean.

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‫So not all code paths return a value in anonymous method.

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‫So it already says anonymous method here.

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‫So what we're just going to say is just return the H where it's greater or equal to 20 and where the

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‫H is less than 30.

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‫And equal 30.

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‫All right.

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‫That's pretty much it.

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‫So here we create a new variable called filter of type filter delegate.

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‫So this is just a variable, right?

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‫Then we assign an anonymous method to it instead of an already defined method.

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‫And then we just make sure that we follow the instructions of that filter delegate, and that is to

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‫return a boolean.

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‫So that's exactly what we're doing.

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‫We're returning true if those two statements are true.

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‫So if the age is greater or equal, 20 or less and equal 30.

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‫So don't forget that semicolon at the end.

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‫That's really important here.

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‫Otherwise this won't work because this is basically like creating a variable.

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‫So it's like int x equals three.

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‫It's pretty much the same thing that we're doing here with this filter delegates, but it's a little

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‫more complicated.

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‫So this year what you see here is an anonymous method because it doesn't have a name, but it basically

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‫behaves like a method.

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‫So now what we can do is we can call our display people.

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‫And we can use our variable filter so we can pass a filter.

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‫You might recall this play, people always had this structure where you had a title right here you had

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‫a title, then you had to pass in the list of people so of person objects, right?

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‫And then you needed to add the filter in here.

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‫And I'm just going to use my filter that I had just set up, which is this filter variable.

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‫So now this filter variable is off type filter delegate, which is what display people requires because

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‫here you see it requires a filter delegate type.

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‫So it's really something interesting because you can on one hand just go ahead and create a method that

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‫follows the delegate description and just use it as we saw here.

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‫But you can also just create a variable which uses an anonymous method using the delegate keyword,

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‫as we have done here, and install it inside of this filter and then use that filter here.

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‫So this will now, of course, not be kids, but it will be between 20 and 30 and it will display all

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‫the people that we have there.

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‫So let's run this code and see if that works.

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‫And we see here between 20 and 30, we have Anatoli, who is 25 years old, but no one else.

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‫So now another approach of an anonymous method, and that is that we can pass an anonymous method directly

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‫as a parameter.

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‫So let's do that real quick.

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‫So we call this display people method and this time I'm just going to display all people, right?

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‫So here all people.

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‫But now we need to pass in, you see here a filter delegate.

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‫So let's go ahead and create an anonymous method.

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‫And in order to do that, we need to use the delegate keyword, right?

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‫They'll get like so and we need to of course still follow the same instruction.

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‫We still need to make sure that our delegate that we're passing is going to be of type filter delegate

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‫if we look at it here at the top.

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‫So here this filter delegate needed to return a pool and it needed a person.

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‫So let's get in the person as the parameter P But then of course, as I stated, we need to also return

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‫something like a boolean.

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‫So basically we can just call it like so.

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‫So here this is a very condensed line of code.

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‫There is a lot going on here.

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‫We're displaying people, but we also have a filter here and this filter, it takes all the people and

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‫it just returns true because it really doesn't matter that much which person we put in here.

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‫So that's basically it.

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‫Otherwise, of course you can also write it like so this will maybe be a little more readable.

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‫So this here is our anonymous method that we are passing as the third parameter as we are just following

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‫the filter delegate.

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‫Set up.

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‫So you see here we're returning a bull and we are taking in a person as the parameter.

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‫So now you see the power of delegates because they are super flexible.

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‫They really just want you to follow a certain structure.

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‫The rest is up to you.

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‫And this gives you as a developer a lot of flexibility when working with delegates.

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‫All right.

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‫So that was a little introduction into anonymous methods.

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‫Let's next look at Lambda Expressions.