CA1023：不應該使用多維索引子
型別名稱 |
IndexersShouldNotBeMultidimensional |
CheckId |
CA1023 |
分類 |
Microsoft.Design |
中斷變更 |
中斷 |
原因
public 或 protected 型別包含使用一個以上之索引的公用或保護之索引子 (Indexer)。
規則描述
索引子 (也就是索引屬性) 應使用單一索引。多維式索引子會大幅降低程式庫的可用性。如果設計需要多個索引，請考慮該型別是否代表邏輯資料存放區。如果不是，請使用方法。
如何修正違規
若要修正此規則的違規情形，請將設計變更為使用長整數 (Long Integer) 或字串索引，或是改用方法而非索引子。
隱藏警告的時機
只有在仔細考慮確實需要非標準索引子之後，才能隱藏此規則的警告。
範例
下列範例所顯示的型別 DayOfWeek03，它的多維式索引子會違反規則。該索引子可視為轉換型別，因此公開為方法較為適當。該型別會在 RedesignedDayOfWeek03 中重新設計以滿足規則。
Imports System
Namespace DesignLibrary
Public Class DayOfWeek03
Private dayOfWeek(,) As String = {{"Wed", "Thu", "..."}, _
{"Sat", "Sun", "..."}}
' ...
Default ReadOnly Property Item(month As Integer, day As Integer) As String
Get
Return dayOfWeek(month - 1, day - 1)
End Get
End Property
End Class
Public Class RedesignedDayOfWeek03
Private dayOfWeek() As String = _
{"Tue", "Wed", "Thu", "Fri", "Sat", "Sun", "Mon"}
Private daysInPreviousMonth() As Integer = _
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30}
Function GetDayOfWeek(month As Integer, day As Integer) As String
Return dayOfWeek((daysInPreviousMonth(month - 1) + day) Mod 7)
End Function
End Class
End Namespace
using System;
namespace DesignLibrary
{
public class DayOfWeek03
{
string[,] dayOfWeek = {{"Wed", "Thu", "..."},
{"Sat", "Sun", "..."}};
// ...
public string this[int month, int day]
{
get
{
return dayOfWeek[month - 1, day - 1];
}
}
}
public class RedesignedDayOfWeek03
{
string[] dayOfWeek =
{"Tue", "Wed", "Thu", "Fri", "Sat", "Sun", "Mon"};
int[] daysInPreviousMonth =
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30};
public string GetDayOfWeek(int month, int day)
{
return dayOfWeek[(daysInPreviousMonth[month - 1] + day) % 7];
}
}
}
using namespace System;
namespace DesignLibrary
{
public ref class DayOfWeek03
{
array<String^, 2>^ dayOfWeek;
public:
property String^ default[int, int]
{
String^ get(int month, int day)
{
return dayOfWeek[month - 1, day - 1];
}
}
DayOfWeek03()
{
dayOfWeek = gcnew array<String^, 2>(12, 7);
dayOfWeek[0,0] = "Wed";
dayOfWeek[0,1] = "Thu";
// ...
dayOfWeek[1,0] = "Sat";
dayOfWeek[1,1] = "Sun";
// ...
}
};
public ref class RedesignedDayOfWeek03
{
static array<String^>^ dayOfWeek =
{"Tue", "Wed", "Thu", "Fri", "Sat", "Sun", "Mon"};
static array<int>^ daysInPreviousMonth =
{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30};
public:
String^ GetDayOfWeek(int month, int day)
{
return dayOfWeek[(daysInPreviousMonth[month - 1] + day) % 7];
}
};
}