转换和拆箱有什么区别？
之间有什么区别？
Expression.Convert(SomeVariableExpression, typeof(T));
在 DLR 的 LINQ 表达式中，this:和 this:
Expression.Unbox(SomeVariableExpression, typeof(T));
有关此的文档似乎有点粗略。
更重要的是，其中哪一个相当于以下 C# 代码：
(ClassA)InstanceOfClassB
Where ClassB has animplicit orexplicit Operator to cast to ClassA?
In the DLR's LINQ Expressions, what is the difference between this:
Expression.Convert(SomeVariableExpression, typeof(T));
and this:
Expression.Unbox(SomeVariableExpression, typeof(T));
The documentation on this seems a bit sketchy.
And more to the point, which one of these is equivalent to this C# code:
(ClassA)InstanceOfClassB
Where ClassB has an implicit or explicit operator to cast to ClassA?
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Unbox 的重要之处在于它为您提供了装箱值的地址。 这确保您可以对未装箱的值调用方法。 如果该方法改变了值类型，那么它会改变装箱版本而不是新副本。 如果您只是执行 Convert，那么您实际上已经制作了装箱值类型的副本，然后调用它的方法会改变副本而不是原始值。
The important thing Unbox is that it gives you the address of the boxed value. This ensures that you can call a method on the unboxed value. If that method mutates the value type then it's mutating the boxed version instead of a new copy. If you merely did Convert then you'd actually have made a copy of the boxed value type and then calling a method on it would mutate the copy and not the original value.
主要区别在于 Epression.Unbox 仅用于从堆中显式拆箱值类型。
Expression.Convert是您想要用来挂钩用户定义的转换（无论是隐式还是显式）的方法。请参阅
Expression.Convert：并且：
Well the main difference is that
Epression.Unboxis only needed for explicit unboxing of a value type off the heap.Expression.Convertis the method you would want to use to hook into a user-defined conversion (whether implicit or explicit).See
Expression.Convert:and also:
一般来说，装箱采用值类型并将其包装在对象中。 拆箱则相反。 您可以将其视为装箱获取寄存器或堆栈值并将其放在堆上，返回指向该值的指针。 拆箱将堆上的对象放入寄存器或堆栈帧中。 底层数据类型保持不变。
将更改一种数据类型转换为另一种数据类型。
In general, boxing takes a value type and wraps it in an object. Unboxing does the reverse. You can think of this as boxing takes a register or stack value and puts it on the heap, returning a pointer to that value. Unboxing takes an object on the heap and puts it into a register or stack frame. The underlying datatype stays the same.
Convert changes one datatype into another.
Expression.Convert 相当于进行强制转换。
Expression.Convert is the equivalent of doing a cast.