Predicate in Net 3.5

[shapper]

Hello,

I have a List(Of MyClass).
MyClass has two properties: Name and City.

I want to find, without using a loop, if there is a item where name =
NameParameter.

I know that I can use a Predicate but in .NET 2.0 Predicates do not
accepted Parameters.

Because of that I used a Predicate Wrapper.

With .NET 3.5 I know this has changed and now it is much easier to do
something like this.

However, I can't find any example of it.

Can someone, please, help me out?

Thanks,
Miguel

[Nicholas Paldino [.NET/C# MVP]]

Miguel,

Well, like it or not, you are going to have to have a loop somewhere, it
just might not be apparent.

In 3.5, if you want to see if there is any item in the list where
NameParameter = some value, you can do this:
// The list.
List<MyClassmyList = ...;

// The value to check against.
string nameParameterValue = ...;

// Does it contain the value?
bool containsValue = myList.Any(item =item.NameParameter ==
nameParameterValue);

The Any extension method is going to perform the loop for you.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard.caspershouse.com

"shapper" <md*****@gmail.comwrote in message
news:c6**********************************@e6g2000p rf.googlegroups.com...

Hello,

I have a List(Of MyClass).
MyClass has two properties: Name and City.

I want to find, without using a loop, if there is a item where name =
NameParameter.

I know that I can use a Predicate but in .NET 2.0 Predicates do not
accepted Parameters.

Because of that I used a Predicate Wrapper.

With .NET 3.5 I know this has changed and now it is much easier to do
something like this.

However, I can't find any example of it.

Can someone, please, help me out?

Thanks,
Miguel

[Jon Skeet [C# MVP]]

shapper <md*****@gmail.comwrote:

I have a List(Of MyClass).
MyClass has two properties: Name and City.

I want to find, without using a loop, if there is a item where name =
NameParameter.

I know that I can use a Predicate but in .NET 2.0 Predicates do not
accepted Parameters.

You can use an anonymous method though:

public bool CheckForItem(string name)
{
return items.Exists(delegate (MyClass item)
{ return item.Name==name;}
);
}

However, I can't find any example of it.

With C# 3 (with or without .NET 3.5) you could use:

public bool CheckForItem(string name)
{
return items.Exists(item =item.Name==name);
}

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
World class .NET training in the UK: http://iterativetraining.co.uk