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将lambda的字符串表示形式编译为lambda

dynamic-linq roslyn scripting c#

Ivan · 技术社区 · 7 年前

我有以下几点 lambda 这很好:

public interface IOhlcv : ITick
{
    decimal Open { get; set; }
    decimal High { get; set; }
    decimal Low { get; set; }
    decimal Close { get; set; }
    decimal Volume { get; set; }
}

c1,c2,c3 你属于那种类型 IList<IOhlcv>

这是 拉姆达 :

(c1, c2, c3) => c1.Close / c2.Close * c3.Close

如果 拉姆达 是一个 string 代表 拉姆达 ,

string lambdaStr = "(c1, c2, c3) => c1.Close / c2.Close * c3.Close"

我该怎么办 compile 这是一场真正的战争 拉姆达 ? 注:(lambdaStr可以动态创建,例如c1、c2、c3可以是任意数量的参数,它们之间有运算符)

我试着用 https://github.com/dotnet/roslyn/wiki/Scripting-API-Samples#expr

这样地:

var options = ScriptOptions.Default.AddReferences(typeof(IOhlcv).Assembly);
var projection = await CSharpScript.EvaluateAsync<IList<decimal>>(projectionString, options);

但我无法让它工作:

Message = "(1,1): error CS1660: Cannot convert lambda expression to type 'IList<decimal>' because it is not a delegate type"

编辑1

甚至试过这个

try
        {
            string lambdaStr = "(c1, c2, c3) => c1.Close / c2.Close * c3.Close";
            var options = ScriptOptions.Default.AddReferences(typeof(IOhlcv).Assembly);
            // this will be a delegate type and you will need to turn it into one that fits
            dynamic projection = await CSharpScript.EvaluateAsync<dynamic>(lambdaStr, options);

        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.ToString());
        }

给我这个 exception :

'Microsoft.CodeAnalysis.Scripting.CompilationErrorException' in Microsoft.CodeAnalysis.Scripting.dll
Microsoft.CodeAnalysis.Scripting.CompilationErrorException: (1,1): error CS1660: Cannot convert lambda expression to type 'object' because it is not a delegate type
   at Microsoft.CodeAnalysis.Scripting.ScriptBuilder.ThrowIfAnyCompilationErrors(DiagnosticBag diagnostics, DiagnosticFormatter formatter)
   at Microsoft.CodeAnalysis.Scripting.ScriptBuilder.CreateExecutor[T](ScriptCompiler compiler, Compilation compilation, Boolean emitDebugInformation, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Scripting.Script`1.GetExecutor(CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.Scripting.Script`1.RunAsync(Object globals, Func`2 catchException, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.CSharp.Scripting.CSharpScript.RunAsync[T](String code, ScriptOptions options, Object globals, Type globalsType, CancellationToken cancellationToken)
   at Microsoft.CodeAnalysis.CSharp.Scripting.CSharpScript.EvaluateAsync[T](String code, ScriptOptions options, Object globals, Type globalsType, CancellationToken cancellationToken)
   at Trady.Form1.<ZipSeries>d__17.MoveNext() in C:\Users\idf\Form1.cs:line 281

编辑2

这个建议让人感觉有什么东西正在靠近,但没有雪茄:

   try
    {
        var options = ScriptOptions.Default.AddReferences(typeof(IOhlcv).Assembly);
        var projection = await CSharpScript.EvaluateAsync<Func<IOhlcv,IOhlcv,IOhlcv,decimal>>(projectionString, options);
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.ToString());
    }

ex = {"(1,18): error CS1061: 'IOhlcv' does not contain a definition for 'close' and no accessible extension method 'close' accepting a first argument of type 'IOhlcv' could be found (are you missing a using directive or an assembly reference?)"}

编辑3

生成“.close”的代码中存在错误。当代码中的“关闭”被更改时 编辑2 作品

它仍然没有回答如何创建一个 拉姆达 这可能需要一段时间 variable number of parameters 自从 Func<IOhlcv,IOhlcv,IOhlcv,decimal> 是硬连线的,但这是向前迈出的一步。

可以 CSharpScript.EvaluateAsync 编译成 delegate 需要可变数量的参数吗?

1 回复 | 直到 7 年前

Maximilian Burszley 7 年前

string lambdaStr = "(c1, c2, c3) => c1.Close / c2.Close * c3.Close";
var options = ScriptOptions.Default.AddReferences(typeof(IOhlcv).Assembly);
// this will be a delegate type and you will need to turn it into one that fits
dynamic projection = await CSharpScript.EvaluateAsync<dynamic>(lambdaStr, options);

// or similar
System.Console.WriteLine(projection(a, b, c));