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Hello.

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In this lecture will focus on Question 35, What are anonymous types?

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Anonymous types are types without names.

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Anonymous types provide a convenient way of encapsulating a set of only properties into a single object

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without having to explicitly define the type first.

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As you can see, to create an object of an anonymous type, we simply use the new keyword and then put

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on the properties we want in the braces.

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Here we created an anonymous type with free properties, name and city of type, string and age of type

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int the properties of anonymous types are read only, so the code modifying them will not compile.

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To understand better what may be the use case for anonymous types, let's consider a simple coding challenge.

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First, let's define a collection of parts.

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Each bird has a name type and wait.

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What we want to do is to build a collection of strings that will contain data about each type, including

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the average weight of pets of this type.

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The result should be sorted by ascending.

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In other words, it should look like this will use Link to do it.

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If you don't know Link and you would like to learn it took Hold My Course Link Tutorial Master the key

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C-sharp library in the last lecture of this course, you can find a discount coupon.

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All right.

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First, we need to group the pets by type.

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For each of the groups, we want to calculate the average weight.

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Well, this works fine, but there is one problem.

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We only selected the average weights of each group now, but we lost the information about the name

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of each of those groups.

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We must change this cult to not select votes as the average weight is afloat, but pairs of prototype

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cells.

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But how should we represent those powers?

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We could define a class struct or a record for it.

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Again, this works, but it seems like a big effort.

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We created a whole separate type for this very specific piece of data will probably never use it in

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a different context, not to mention that this name is a bit awkward.

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But how else could we call it?

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There is really no good name for this very specific set of data.

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The solution is to use an anonymous type.

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Anonymous type is a type defined right where it's needed without even giving it a name.

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It's perfect for use cases like ours when the type is small and temporary and we don't intend to use

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it anywhere else.

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All right.

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So now this anonymous object will hold a prototype and a float representing the average weight of births

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of this type.

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The only thing left to do is to order this data and make it to some readable strings.

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Let's make sure this works as expected.

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All right.

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Seems like our code using anonymous type works correctly.

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Let's take another look at this type because it doesn't even have a name will not be able to use it

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anywhere else because how could we refer to it if we don't know its name?

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Actually, the compiler gives it a name that can be seen in the common intermediate language.

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But even if we use it doesn't to find it, it won't be possible to use it just to satisfy your curiosity.

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I joked how the compiler named this particular type.

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He was the name of the anonymous type we defined.

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As you can see, it's not very readable.

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Please note that from the perspective of the common language runtime, anonymous types are no different

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than other types.

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It's least the most important information about anonymous types.

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They contain only root only properties.

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No other kinds of class members, such as methods or events, are valid.

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If no names are given to the properties of the anonymous type, the compiler will use the name of the

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property that was used to set the value of the anonymous Typekit property.

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For example, if instead of this, we will do this.

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The name of the first property would be key, the same as the name of the property assigned to it when

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this assigned value is not a property or a field.

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It must be given a name, for example.

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In this case, it doesn't work because this value is calculated and it doesn't have a name.

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We must give it a name.

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Otherwise, this error will be seen.

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Anonymous types are class objects derived directly from the system object type.

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They can't be cast one of our type.

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They override the equals and the cash court methods to support value based equality.

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Two anonymous objects with the same values will have the same hash codes, and the equals method will

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return to form them.

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Please note that the equality operator is not overloaded, so it will return false because there are

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reference types and they differ by reference.

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Also, anonymous objects support non-destructive mutation.

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Well, if there was keyword.

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Remember, non-destructive mutation is not changing the original object, but rather creating a new

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one.

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We've turned to values.

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Let's summarize Anonymous types are types without names.

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They encapsulate a set of only properties into a single object without having to explicitly define a

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type first.

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They are most often use defined small, temporary types that we don't intend to use anywhere else.

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During the interview, you can be asked Can we modify the value of an anonymous type of property?

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No.

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All properties of anonymous types are with only one.

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Should we owned one, should we not use anonymous types?

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The best use case for on animal stopes is one.

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The type we want to use is simple and you'll come to some specific context and it will not be used anywhere

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else.

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Anonymous types are very often used as temporary objects in complex link queries.

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If a type is complex or we want to use it, it should not be anonymous.

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Also, anonymous types can only provide only properties.

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They can't have methods, fields, events, etc. So if we need any of those features, the anonymous

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types will not work for us.

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Our anonymous types, value or reference types, they are reference types since they are crosses, but

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they support value based equality with the equals method.

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In other words, two anonymous objects with the same values of properties would be considered equal

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by the equals method, even if the references are different.

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All right, that's it about anonymous types.

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Thanks for watching and see you in the next video.