C#发出，类型值比较 [英] C# emit , type value compare

问题描述

我的预览问题如何编写if语句

在 setterBuilder 语句中，如果我比较新值和旧值，则有3种方法.

in setterBuilder statement, if i compare new value and old value , there are 3 ways .

1. 使用@DudiKeleti写道的" op_Inequality ".
2. 使用 property.PropertyType.GetMethod("Equals" ，有时会出现错误"System.NullReferenceException"
3. 使用 typeof(object).GetMethod("Equals" .

1. use "op_Inequality" as @DudiKeleti writes.
2. use property.PropertyType.GetMethod("Equals" , sometimes there are errors , "System.NullReferenceException"
3. use typeof(object).GetMethod("Equals" .

我的问题是什么

1. 某些数据类型(例如int)不具有"op_Inequality"，那么我该怎么办?

1. some data type , for example , int , doesn't has "op_Inequality" , what should i do then ?

如果我使用 typeof(object).GetMethod ，我还应该使用调试模型，否则会出现错误， System.AccessViolationException:'试图读取或写入受保护的内存.这通常表明其他内存已损坏.'

if i use typeof(object).GetMethod , i should alse use debug model ,otherwise, there are errors , System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

有人可以帮助我解决这些问题吗?

can somebody help me with the problems ?

更新1

我得到了一个屏幕快照.

i got a screen-snap .

推荐答案

感谢大家.我得到了对 EntityProxyFactory .有帮助 我的代码在下面.

Thanks everyone. I got a reference to EntityProxyFactory. It's helpful and my code is below.

        Label exitSet = setIl.DefineLabel();
        MethodInfo op_inequality = propertyType.GetMethod("op_Inequality", new Type[] { propertyType, propertyType });
        if (op_inequality != null)
        {
            setIl.Emit(OpCodes.Ldarg_0);
            setIl.Emit(OpCodes.Ldfld, fb);
            setIl.Emit(OpCodes.Ldarg_1);
            setIl.Emit(OpCodes.Call, op_inequality);
            setIl.Emit(OpCodes.Brfalse_S, exitSet);
        }
        else
        {
            // Use object inequality
            setIl.Emit(OpCodes.Ldarg_0);
            setIl.Emit(OpCodes.Ldfld, fb);
            if (propertyType.IsValueType)
            {
                setIl.Emit(OpCodes.Box, propertyType);
            }
            setIl.Emit(OpCodes.Ldarg_1);
            if (propertyType.IsValueType)
            {
                setIl.Emit(OpCodes.Box, propertyType);
            }
            setIl.Emit(OpCodes.Call, EqualsMethod);
            setIl.Emit(OpCodes.Brtrue_S, exitSet);
        }


        setIl.Emit(OpCodes.Ldarg_0); // load string literal
        setIl.Emit(OpCodes.Ldarg_1); // value
        //-----------------important---------
        if (propertyType.IsValueType)
        {
            setIl.Emit(OpCodes.Box, propertyType);
        }
        setIl.Emit(OpCodes.Ldstr, property.Name);

        var parentType = tb.BaseType;
        //if (parentType == null)
        //    throw new Exception($"Interface {tb.Name} should be inherited from \"IDbEntity\". ");

        var m = parentType.GetMethod("ValueChanged", BindingFlags.Instance | BindingFlags.NonPublic);
        setIl.Emit(OpCodes.Call, m);

希望我的代码对您有所帮助.

I hope my code will help you.

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