[API Proposal]: Add overload of Type.GetMethod that takes a name, generic parameter count, binding flags and parameter types

[Neme12]

Background and motivation

In #42753, an overload of Type.GetMethod was added that takes a name, binding flags, and paramater types, to simplify usage when people don't care about the binder and paramater modifiers (which as I understand is there only for COM), which basically nobody passes in ever. However no equivalent overload was added that also takes genericParameterCount at the beginning. This is the overload I always use, even when the method isn't generic and I pass in 0, to be as specific as possible and make sure that my code still works even in case there is a generic overload added in the future. It seems that all the other overloads have an equivalent that takes genericParameterCount at the beginning, so this would just square off the feature in my opinion.

API Proposal

 namespace System;

 public abstract partial class Type
 {
     public MethodInfo? GetMethod(string name, int genericParameterCount, Type[] types);
     public MethodInfo? GetMethod(string name, int genericParameterCount, Type[] types, ParameterModifier[]? modifiers);
+    public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Type[] types);
     public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Binder? binder, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Binder? binder, CallingConventions callConvention, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name);
     public MethodInfo? GetMethod(string name, Type[] types);
     public MethodInfo? GetMethod(string name, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Type[] types);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Binder? binder, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Binder? binder, CallingConventions callConvention, Type[] types, ParameterModifier[]? modifiers);
 }

API Usage

using System.Reflection;

var method = typeof(C).GetMethod("M", 0, BindingFlags.Public | BindingFlags.Instance, Array.Empty<Type>());
// or "Type.EmptyTypes" instead of "Array.Empty<Type>()"

class C
{
    public void M();
}

Alternative Designs

Original issue alternative (not proposed): optionally, to square off the set of overloads completely, with complete parity between the ones that take genericParameterCount and the ones that don't (7 overloads for each):

 namespace System;

 public abstract partial class Type
 {
+    public MethodInfo? GetMethod(string name, int genericParameterCount);
     public MethodInfo? GetMethod(string name, int genericParameterCount, Type[] types);
     public MethodInfo? GetMethod(string name, int genericParameterCount, Type[] types, ParameterModifier[]? modifiers);
+    public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr);
+    public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Type[] types);
     public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Binder? binder, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Binder? binder, CallingConventions callConvention, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name);
     public MethodInfo? GetMethod(string name, Type[] types);
     public MethodInfo? GetMethod(string name, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Type[] types);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Binder? binder, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Binder? binder, CallingConventions callConvention, Type[] types, ParameterModifier[]? modifiers);
 }

Risks

No response

[ghost]

Tagging subscribers to this area: @dotnet/area-system-reflection
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Background and motivation

In #42753, an overload of Type.GetMethod was added that takes a name, binding flags, and paramater types, to simplify usage when people don't care about the binder and paramater modifiers (which as I understand is there only for COM), which basically nobody passes in ever. However no equivalent overload was added that also takes genericParameterCount at the beginning. This is the overload I always use, even when the method isn't generic and I pass in 0, to be as specific as possible and make sure that my code still works even in case there is a generic overload added in the future. It seems that all the other overloads have an equivalent that takes genericParameterCount at the beginning, so this would just square off the feature in my opinion.

API Proposal

 namespace System;

 public abstract partial class Type
 {
     public System.Reflection.MethodInfo? GetMethod(string name) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, int genericParameterCount, System.Type[] types) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, int genericParameterCount, System.Type[] types, System.Reflection.ParameterModifier[]? modifiers) { throw null; }
+    public System.Reflection.MethodInfo? GetMethod(string name, int genericParameterCount, System.Reflection.BindingFlags bindingAttr, System.Type[] types) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, int genericParameterCount, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder? binder, System.Type[] types, System.Reflection.ParameterModifier[]? modifiers) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, int genericParameterCount, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder? binder, System.Reflection.CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[]? modifiers) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, System.Type[] types) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, System.Type[] types, System.Reflection.ParameterModifier[]? modifiers) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, System.Reflection.BindingFlags bindingAttr) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, System.Reflection.BindingFlags bindingAttr, System.Type[] types) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder? binder, System.Type[] types, System.Reflection.ParameterModifier[]? modifiers) { throw null; }
     public System.Reflection.MethodInfo? GetMethod(string name, System.Reflection.BindingFlags bindingAttr, System.Reflection.Binder? binder, System.Reflection.CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[]? modifiers) { throw null; }
 }

API Usage

using System.Reflection;

var method = typeof(C).GetMethod("M", 0, BindingFlags.Public | BindingFlags.Instance, Array.Empty<Type>());

class C
{
    public void M();
}

Alternative Designs

No response

Risks

No response

Author:	Neme12
Assignees:	-
Labels:	api-suggestion, area-System.Reflection
Milestone:	-

[steveharter]

However no equivalent overload was added that also takes genericParameterCount at the beginning.

The original request would help the common cases:

public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Type[] types);

However, I'm not so sure about the other 2 since they remove the Type[] parameter which is a good practice for open-ended method lookup to disambiguate similar methods.

[Neme12]

Right, I'm only interested in that one, I just added the proposal for the rest of them only as an idea if parity and consistency is desired.

[steveharter]

I think it makes sense to add this to v9:

public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Type[] types);

[TheMaximum]

I'd be interested in taking this up if it gets through the API review :)

[bartonjs]

Video

Looks good as proposed.

 namespace System;

 public abstract partial class Type
 {
     public MethodInfo? GetMethod(string name, int genericParameterCount, Type[] types);
     public MethodInfo? GetMethod(string name, int genericParameterCount, Type[] types, ParameterModifier[]? modifiers);
+    public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Type[] types);
     public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Binder? binder, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, int genericParameterCount, BindingFlags bindingAttr, Binder? binder, CallingConventions callConvention, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name);
     public MethodInfo? GetMethod(string name, Type[] types);
     public MethodInfo? GetMethod(string name, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Type[] types);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Binder? binder, Type[] types, ParameterModifier[]? modifiers);
     public MethodInfo? GetMethod(string name, BindingFlags bindingAttr, Binder? binder, CallingConventions callConvention, Type[] types, ParameterModifier[]? modifiers);
 }