What is a Predicate <T> delegate?

Hi puran,
Predicate delegate is a generic delegate type which is often passed as parameter in Search type functions like Find & Remove in Generic Collections.
Suppose you have a List of your user defined objects.
Class Person { string name; int id;}
and you have create a list of class Persons : List objPList=new List;
then you might want to set your own rule for finding a particular object from the entire list
So you'll have to pass a Predicat delegate( a function pointer type).
where you define your own method (either anynomous or declared)
int currentID=GetID();// Your application code.
.FindAll(delegate(Person obj) { return obj.Id== currentID; }));
Here is the formal definition :

The Predicate<(Of <(T>)>) is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. The elements of the current List<(Of <(T>)>) are individually passed to the Predicate<(Of <(T>)>) delegate, moving forward in the List<(Of <(T>)>), starting with the first element and ending with the last element. Processing is stopped when a match is found.

Hope it helps.

1 Reply

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naura pax17y ago
Hi puran,
Predicate delegate is a generic delegate type which is often passed as parameter in Search type functions like Find & Remove in Generic Collections.
Suppose you have a List of your user defined objects.
Class Person { string name; int id;}
and you have create a list of class Persons : List objPList=new List;
then you might want to set your own rule for finding a particular object from the entire list
So you'll have to pass a Predicat delegate( a function pointer type).
where you define your own method (either anynomous or declared)
int currentID=GetID();// Your application code.
.FindAll(delegate(Person obj) { return obj.Id== currentID; }));
Here is the formal definition :

The Predicate<(Of <(T>)>) is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. The elements of the current List<(Of <(T>)>) are individually passed to the Predicate<(Of <(T>)>) delegate, moving forward in the List<(Of <(T>)>), starting with the first element and ending with the last element. Processing is stopped when a match is found.

Hope it helps.
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