Func is a family of delegate types in the .Net framework.
Func is a family of delegate types in the .net framework. They are in the System namespace and can be used to represent a function that returns a value and has zero or more parameters.
Questions tagged [func]
1154 questions
9
votes
0 answers
why C# Func lambda expression requires cast for result
I need to understand about Func type expression deeper.
public class TheResult : IResultEntry {
...
}
With above class, why does below second method require cast?
I can read the error message of course, but hard to understand.
// Success
public…
Youngjae
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9
votes
1 answer
Convert Func delegate to a string
Is there any way to convert an existing Func delegate to a string like that:
Func func = (i) => i*2;
string str = someMethod(func); // returns "Func func = (i) => i*2"
or at least smth close to it
curious
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9
votes
1 answer
For Func, where A extends T, A does not satisfy for T
Okay, let me set the scene:
We have a function used within our code that takes a function and does some logging around it and then returns the result. It looks a little something like this.
TResponse LoggedApiCall(Func
Kira Namida
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9
votes
3 answers
C# method accepting a predicate - does this look ok?
I'd like a method that has the following API:
//get all users with a role of admin
var users = myRepository.GetUsers(u => u.Role == Role.Admin);
Will something like this work?
IList GetUsers(Func predicate)
{
var…
Ben Aston
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9
votes
1 answer
How to use a Func in an expression with Linq to Entity Framework?
I am trying to write a linq to entity extension method that takes a Func to select a property Id and compare it against a list of ids.
Classes
public class A
{
public int AId { get; set; }
}
public class B
{
public int BId { get; set;…
David
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9
votes
4 answers
Func<> getting the parameter info
How to get the value of the passed parameter of the Func<> Lambda in C#
IEnumerable _data = await accountRepo.GetAsync();
string _query = "1011";
Accounts = _data.Filter(p => p.AccountNumber == _query);
and this is my extension…
Vincent Dagpin
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9
votes
3 answers
C# - How do I define an inline method Func as a parameter?
I've written a simple SessionItem management class to handle all those pesky null checks and insert a default value if none exists. Here is my GetItem method:
public static T GetItem(string key, Func defaultValue)
{
if…
tags2k
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9
votes
2 answers
T of Func is inferred from output of lambda expression only when S and T are different?
When S and T are different, this works:
public static void Fun(Func func)
{
}
Fun((string s) => true); //compiles, T is inferred from return type.
But,
public static void Fun(Func func)
{
}
Fun(t => true); //can't infer…
nawfal
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8
votes
1 answer
Type '()' cannot conform to 'View'; only struct/enum/class types can conform to protocols calling calling functions with swift ui
I have a SwiftUI View called MyWatchView with this stack:
VStack (alignment: .center)
{
HStack
{
Toggle(isOn: $play)
{
Text("")
}
.padding(.trailing, 30.0)
.hueRotation(Angle.degrees(45))
…
Derick Mathews
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8
votes
1 answer
Why does adding throw inside a lambda without a return value get inferred as a Func and not as Action?
I'm running into an issue where some test code for a library I'm writing won't compile due to an ambiguous call but the usage seemed clear to me. Upon further investigation I've found that adding throw inside a lambda that has no return value seems…
Cameron Owen
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votes
4 answers
How can I force a throw to be a statement and not an expression (in a lambda expression)?
Starting from C# 7.0 the throw keyword can be used both as an expression and as a statement, which is nice.
Though, consider these overloads
public static void M(Action doIt) { /*use doIt*/ }
public static void M(Func doIt) { /*use doIt*/…
Ulf Åkerstedt
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8
votes
2 answers
Optimizing Func.Invoke() generated from expression tree
I am working on an automation for instantiating classes dynamically.
I decided to write an expression tree that would generate a Func, that could instantiate my class for me. However, I am noticing 3x slower performance of my Func as opposed to…
Hentov
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8
votes
2 answers
c# Predicate with no parameters
I'm trying to pass a Predicate to a function but it has no input. I'm actually trying to delay the computation until the call is made.
Is there a way to use c# Predicate type for that? If not why.
I know a way to do this with Func
Func…
Dolev
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8
votes
2 answers
C# Action and Func parameter overloads
I need a method that takes an Action (or a Func), but the Action has a mixed number of parameters. What is the most straight forward and compact way to implement these overloads:
public void Execute(Action action, T param) {
// TODO:…
Seb Nilsson
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8
votes
3 answers
Strongly typed url action
I've read multiple posts and blogs similar to
Delegate-based strongly-typed URL generation in ASP.NET MVC
But none of them really quite do what I'd like to do. Currently I have a hybrid approach like:
// shortened for Brevity
public static Exts
{ …
Erik Philips
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