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从Powershell中使用表达式<Func>参数调用C#方法

lambda powershell c#

2

Mark · 技术社区 · 9 年前

public static class Class1
{
    public static string Method1(Expression<Func<string>> efs)
    {
        return efs.Compile().Invoke();
    }
}

从C#中调用它非常简单:

Class1.Method1(() => "Hello World");

Add-Type -Path "ClassLibrary1.dll"
$func = [Func[string]] { return "Hello World" }
$exp = [System.Linq.Expressions.Expression]::Call($func.Method);
[ClassLibrary1.Class1]::Method1($exp)

但这会导致一个错误:

Exception calling "Call" with "1" argument(s): "Incorrect number of arguments supplied for call to method 'System.String lambda_method(System.Runtime.CompilerServices.Closure)'"
At C:\Users\Mark\Documents\Visual Studio 2015\Projects\ClassLibrary1\ClassLibrary1\test.ps1:4 char:1
+ $exp = [System.Linq.Expressions.Expression]::Call($func.Method);
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : ArgumentException
+ $exp = [System.Linq.Expressions.Expression]::Call($func.Method);
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : ArgumentException

$func 不正确;有什么想法吗?

1 回复 | 直到 9 年前

1

3

Mark 9 年前

好的,找到了(感谢@DavidG的链接)。关键是写出 System.Linq.Expressions.Expression 首先是C#中的树。之后,转换到Powershell很容易:

因此,在C#中:

Class1.Method1(() => "Hello World");

var exp = Expression.Constant("Hello World", typeof(string));
var lamb = Expression.Lambda<Func<string>>(exp);
Class1.Method1(lamb);

$exp = [System.Linq.Expressions.Expression]::Constant("Hello World", [string]);
$lamb = [System.Linq.Expressions.Expression]::Lambda([Func[string]], $exp);
[ClassLibrary1.Class1]::Method1($lamb);