method-group | 易学教程

Delegate instance allocation with method group compared to

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问题 I started to use the method group syntax a couple of years ago based on some suggestion from ReSharper and recently I gave a try to ClrHeapAllocationAnalyzer and it flagged every location where I was using a method group in a lambda with the issue HAA0603 - This will allocate a delegate instance . As I was curious to see if this suggestion was actually useful, I wrote a simple console app for the 2 cases. Code1: class Program { static void Main(string[] args) { var temp = args.AsEnumerable();

Delegate instance allocation with method group compared to

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Difference between lambda expression and method group

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问题 What's the difference between Class1.Method1<Guid, BECustomer>("cId", Facade.Customers.GetSingle); and Class1.Method1<Guid, BECustomer>("cId", x => Facade.Customers.GetSingle(x)); ? Resharper suggests to use the first expression. 回答1: There is no difference in regards to the result. However, the second one creates an additional redirection: The code will first call your anonymous method the takes one parameter named x and that in turn calls Facade.Customers.GetSingle with that parameter. This

Overloaded method-group argument confuses overload resolution?

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问题 The following call to the overloaded Enumerable.Select method: var itemOnlyOneTuples = "test".Select<char, Tuple<char>>(Tuple.Create); fails with an ambiguity error (namespaces removed for clarity): The call is ambiguous between the following methods or properties: 'Enumerable.Select<char,Tuple<char>> (IEnumerable<char>,Func<char,Tuple<char>>)' and 'Enumerable.Select<char,Tuple<char>> (IEnumerable<char>, Func<char,int,Tuple<char>>)' I can certainly understand why not specifying the type

Cannot convert from 'method group' to 'System.Action<object>' error

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问题 I have created the following function: public void DelegatedCall(Action<Object> delegatedMethod) And defined the following method public void foo1(String str) { } However, when I try to call DelegateCall with foo1 : DelegatedCall(foo1); ...I get the following compiler error: Argument 1: cannot convert from 'method group' to 'System.Action<object>' What is the reason for this error and how can I correct it? Unfortunately, casting foo1 to Action is not an option. 回答1: DelegatedCall expects a

Cannot Assign because it is a method group C#?

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问题 Cannot Assign "AppendText" because it is a "method group". public partial class Form1 : Form { String text = ""; public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { String inches = textBox1.Text; text = ConvertToFeet(inches) + ConvertToYards(inches); textBox2.AppendText = text; } private String ConvertToFeet(String inches) { int feet = Convert.ToInt32(inches) / 12; int leftoverInches = Convert.ToInt32(inches) % 12; return (feet + " feet and " +

C# method group strangeness

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问题 I discovered something very strange that I'm hoping to better understand. var all = new List<int[]>{ new int[]{1,2,3}, new int[]{4,5,6}, new int[]{7,8,9} }; all.ForEach(n => n.ForEach(i => Console.WriteLine(i))); which can be rewritten as: ... all.ForEach(n => n.ForEach(Console.WriteLine)); How is it possible to leave out the lambda expression parameter (i=>) and still have the current item passed to console.WriteLine? Thanks for any insight. -Keith 回答1: List<T>.ForEach is looking for an

Cannot Assign to 'Money' Because It Is a 'Method Group'

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问题 I'm doing a project for class, and I have to call the Money function from my Player class. However, I do not know how to change Money into something else that is not a Method Group . I don't know much programming, so my range of solutions is rather small. Also, the instructor said I cannot make any changes to the Main class, only to the Player class. Here's the code for the Main class: p1.Money += 400; And here's the 'Money' function from my Player class: public int Money () { return money; }

Cannot convert from 'method group' to 'System.Action<object>' error

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I have created the following function: public void DelegatedCall(Action<Object> delegatedMethod) And defined the following method public void foo1(String str) { } However, when I try to call DelegateCall with foo1 : DelegatedCall(foo1); ...I get the following compiler error: Argument 1: cannot convert from 'method group' to 'System.Action<object>' What is the reason for this error and how can I correct it? Unfortunately, casting foo1 to Action is not an option. CodesInChaos DelegatedCall expects a delegate that takes any object as an argument. But your function foo1 that you are passing to

Convert Method Group to Expression

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I'm trying to figure out of if there is a simple syntax for converting a Method Group to an expression. It seems easy enough with lambdas, but it doesn't translate to methods: Given public delegate int FuncIntInt(int x); all of the below are valid: Func<int, int> func1 = x => x; FuncIntInt del1 = x => x; Expression<Func<int, int>> funcExpr1 = x => x; Expression<FuncIntInt> delExpr1 = x => x; But if i try the same with an instance method, it breaks down at the Expressions: Foo foo = new Foo(); Func<int, int> func2 = foo.AFuncIntInt; FuncIntInt del2 = foo.AFuncIntInt; Expression<Func<int, int>>