Dim
pt
As
New
Point(
0
,
0
)pt
+=
New
Size(
10
,
10
)
C# 中没有问题。在 VB.NET 中就不能编译，错误是
Operator '+' is not defined for types 'System.Drawing.Point' and 'System.Drawing.Size'.
其实看一下 Point 的il 代码，已经有了一个加法的重载
.method
public
hidebysig specialname
static
valuetype System.Drawing.Point op_Addition(valuetype System.Drawing.Point pt, valuetype System.Drawing.Size sz) cil managed
{
// Code size 36 (0x24) .maxstack 8 IL_0000: ldarga.s pt IL_0002: call instance int32 System.Drawing.Point::get_X() IL_0007: ldarga.s sz IL_0009: call instance int32 System.Drawing.Size::get_Width() IL_000e: add IL_000f: ldarga.s pt IL_0011: call instance int32 System.Drawing.Point::get_Y() IL_0016: ldarga.s sz IL_0018: call instance int32 System.Drawing.Size::get_Height() IL_001d: add IL_001e: newobj instance void System.Drawing.Point::.ctor(int32, int32) IL_0023: ret
}
//
end of method Point::op_Addition
无奈只好改成：
Dim
pt
As
New
Point(
0
,
0
) pt
=
Point.op_Addition(pt,
New
Size(
10
,
10
))
查了一下，msdn mag 最新的一期提到了这个问题，其实原因很简单，vb.net 的compiler 还没有100% 对运算符重载支持的足够好。
原文地址：http://www.msdn.microsoft.com/msdnmag/issues/04/12/AdvancedBasics/default.aspx