Predicate with param

[Mirek Endys]

Is there a possibility to write an Predicate with param?

I need to look for a value in Array, or in List, but this value is variable.
How do I write something like this:

class MyObject
{
public Guid Id;
public string Caption;
}


List<MyObject> _myList = new List<MyObject>()

..... here is code for filling the list.....

now I need somehing like this:

private static bool MatchID(MyObject item, Guid id) // this is
impossible???
{
return (item.Id == id);
}

_myList.Find(MatchID, searchid) // this is impossible.... ????

Must I enumerate the List by foreach or is it possible to do it by another
way.

Thanks

 

[Mattias Sjögren]

_myList.Find(MatchID, searchid) // this is impossible.... ????

Must I enumerate the List by foreach or is it possible to do it by another
way.

You can create an anonymous delegate, something like

_myList.Find(delegate (MyObject item) { item.Id == searchid; });


Mattias

 

[Jay B. Harlow [MVP - Outlook]]

Mirek,
I get the impression that System.Predicate was really intended for anonymous
delegates, rather then actual methods in C# or VB.

Something like:

List<MyObject> _myList = new List<MyObject>();

Guid id = ...

_myList.Find(MatchID, delegate()
{
return (item.Id == id);
}
);


An good introduction to anonymous delegates:
http://msdn.microsoft.com/msdnmag/issues/04/05/C20/default.aspx

--
Hope this helps
Jay [MVP - Outlook]
..NET Application Architect, Enthusiast, & Evangelist
T.S. Bradley - http://www.tsbradley.net


| Is there a possibility to write an Predicate with param?
|
| I need to look for a value in Array, or in List, but this value is
variable.
| How do I write something like this:
|
| class MyObject
| {
| public Guid Id;
| public string Caption;
| }
|
|
| List<MyObject> _myList = new List<MyObject>()
|
| .... here is code for filling the list.....
|
| now I need somehing like this:
|
| private static bool MatchID(MyObject item, Guid id) // this is
| impossible???
| {
| return (item.Id == id);
| }
|
| _myList.Find(MatchID, searchid) // this is impossible.... ????
|
| Must I enumerate the List by foreach or is it possible to do it by another
| way.
|
| Thanks
|
|
|
|
|
|
|
|
|
|

 

[James Curran]

I don't have VS2005 available here at work, so I can't test this, but
shouldn't this work?

Predicate<MyObject> IdEquals(Guid id)
{
return delegate (MyObject item) { return (item.Id == id);}
}

// :
// :
// :

List<MyObject> _myList = new List<MyObject>();

Guid id = ...

_myList.Find(IdEquals(id));

--
Truth,
James Curran
[erstwhile VC++ MVP]

Home: www.noveltheory.com Work: www.njtheater.com
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