CA1011:考虑将基类型作为参数传递
类型名 |
ConsiderPassingBaseTypesAsParameters |
CheckId |
CA1011 |
类别 |
Microsoft.Design |
是否重大更改 |
是 |
原因
某方法声明包含一个派生类型的形参,且该方法仅调用该参数的基类型的成员。
规则说明
在方法声明中将基类型指定为参数时,可以将派生自基类型的任何类型作为相应的参数传递给方法。在方法体中使用该变量时,所执行的特定方法取决于该变量的类型。如果不需要派生类型提供的其他功能,则使用基类型将使方法可以得到更广泛的使用。
如何解决冲突
要修复与该规则的冲突,请将参数的类型更改为其基类型。
何时禁止显示警告
可以安全地禁止显示此规则发出的警告
如果该方法需要由派生的类型提供的特定功能
- 或 -
强制要求只有该派生类型或另一个派生类型传递给方法。
在这些情况下,代码将更为可靠,因为编译器和运行时会提供强类型检查。
示例
下面的示例演示与该规则冲突的方法 ManipulateFileStream,此方法只能与 FileStream 对象一起使用。第二个方法 ManipulateAnyStream 将 FileStream 参数替换为 Stream,从而满足该规则。
Imports System
Imports System.IO
Namespace DesignLibrary
Public Class StreamUser
Sub ManipulateFileStream(ByVal stream As IO.FileStream)
If stream Is Nothing Then Throw New ArgumentNullException("stream")
Dim anInteger As Integer = stream.ReadByte()
While (anInteger <> -1)
' Do something.
anInteger = stream.ReadByte()
End While
End Sub
Sub ManipulateAnyStream(ByVal anyStream As IO.Stream)
If anyStream Is Nothing Then Throw New ArgumentNullException("anyStream")
Dim anInteger As Integer = anyStream.ReadByte()
While (anInteger <> -1)
' Do something.
anInteger = anyStream.ReadByte()
End While
End Sub
End Class
Public Class TestStreams
Shared Sub Main()
Dim someStreamUser As New StreamUser()
Dim testFileStream As New FileStream( _
"test.dat", FileMode.OpenOrCreate)
Dim testMemoryStream As New MemoryStream(New Byte() {})
' Cannot be used with testMemoryStream.
someStreamUser.ManipulateFileStream(testFileStream)
someStreamUser.ManipulateAnyStream(testFileStream)
someStreamUser.ManipulateAnyStream(testMemoryStream)
testFileStream.Close()
End Sub
End Class
End Namespace
using System;
using System.IO;
namespace DesignLibrary
{
public class StreamUser
{
int anInteger;
public void ManipulateFileStream(FileStream stream)
{
while ((anInteger = stream.ReadByte()) != -1)
{
// Do something.
}
}
public void ManipulateAnyStream(Stream anyStream)
{
while ((anInteger = anyStream.ReadByte()) != -1)
{
// Do something.
}
}
}
class TestStreams
{
static void Main()
{
StreamUser someStreamUser = new StreamUser();
MemoryStream testMemoryStream = new MemoryStream(new byte[] { });
using (FileStream testFileStream =
new FileStream("test.dat", FileMode.OpenOrCreate))
{
// Cannot be used with testMemoryStream.
someStreamUser.ManipulateFileStream(testFileStream);
someStreamUser.ManipulateAnyStream(testFileStream);
someStreamUser.ManipulateAnyStream(testMemoryStream);
}
}
}
}
using namespace System;
using namespace System::IO;
namespace DesignLibrary
{
public ref class StreamUser
{
int anInteger;
public:
void ManipulateFileStream(FileStream^ stream)
{
while((anInteger = stream->ReadByte()) != -1)
{
// Do something.
}
}
void ManipulateAnyStream(Stream^ anyStream)
{
while((anInteger = anyStream->ReadByte()) != -1)
{
// Do something.
}
}
};
}
using namespace DesignLibrary;
static void main()
{
StreamUser^ someStreamUser = gcnew StreamUser();
FileStream^ testFileStream =
gcnew FileStream("test.dat", FileMode::OpenOrCreate);
MemoryStream^ testMemoryStream =
gcnew MemoryStream(gcnew array<Byte>{});
// Cannot be used with testMemoryStream.
someStreamUser->ManipulateFileStream(testFileStream);
someStreamUser->ManipulateAnyStream(testFileStream);
someStreamUser->ManipulateAnyStream(testMemoryStream);
testFileStream->Close();
}