FieldInfo.IsInitOnly プロパティ
定義
重要
一部の情報は、リリース前に大きく変更される可能性があるプレリリースされた製品に関するものです。 Microsoft は、ここに記載されている情報について、明示または黙示を問わず、一切保証しません。
フィールドをコンストラクターの本体だけでしか設定できないのかどうかを示す値を取得します。
public:
property bool IsInitOnly { bool get(); };public bool IsInitOnly { get; }member this.IsInitOnly : boolPublic ReadOnly Property IsInitOnly As Booleanプロパティ値
フィールドに true 属性が設定されている場合は InitOnly。それ以外の場合は false。
実装
例
次の例では、2 つのフィールドが作成されます。 2 番目のフィールドは読み取り専用で、アクセサーが設定trueされておらず、 IsInitOnly .
using namespace System;
using namespace System::Reflection;
//Make two fields, one public and one read-only.
public ref class Myfielda
{
public:
String^ field;
Myfielda()
: field( "A - public field" )
{}
property String^ Field
{
String^ get()
{
return field;
}
void set( String^ value )
{
if ( field != value )
{
field = value;
}
}
}
};
public ref class Myfieldb
{
private:
String^ const field;
public:
Myfieldb()
: field( "B - readonly field" )
{}
property String^ Field
{
String^ get()
{
return field;
}
}
};
int main()
{
Console::WriteLine( "\nReflection.FieldInfo" );
Myfielda^ myfielda = gcnew Myfielda;
Myfieldb^ myfieldb = gcnew Myfieldb;
//Get the Type and FieldInfo.
Type^ MyTypea = Type::GetType( "Myfielda" );
FieldInfo^ Myfieldinfoa = MyTypea->GetField( "field", static_cast<BindingFlags>(BindingFlags::Public | BindingFlags::Instance) );
Type^ MyTypeb = Type::GetType( "Myfieldb" );
FieldInfo^ Myfieldinfob = MyTypeb->GetField( "field", static_cast<BindingFlags>(BindingFlags::NonPublic | BindingFlags::Instance) );
//Modify the fields.
//Note that Myfieldb is not modified, as it is
//read-only (IsInitOnly is True).
myfielda->field = "A- modified";
//Myfieldb.field = "B- modified";
//For the first field, get and display the name, field, and IsInitOnly state.
Console::Write( "\n{0} - {1}, IsInitOnly = {2} ", MyTypea->FullName, Myfieldinfoa->GetValue( myfielda ), Myfieldinfoa->IsInitOnly );
//For the second field get and display the name, field, and IsInitOnly state.
Console::Write( "\n{0} - {1}, IsInitOnly = {2} ", MyTypeb->FullName, Myfieldinfob->GetValue( myfieldb ), Myfieldinfob->IsInitOnly );
return 0;
}
using System;
using System.Reflection;
//Make two fields, one public and one read-only.
public class Myfielda
{
public string field = "A - public modifiable field";
}
public class Myfieldb
{
public readonly string field = "B - readonly field";
}
public class Myfieldinfo
{
public static int Main()
{
Console.WriteLine("\nReflection.FieldInfo");
Myfielda Myfielda = new Myfielda();
Myfieldb Myfieldb = new Myfieldb();
//Get the Type and FieldInfo.
Type MyTypea = typeof(Myfielda);
FieldInfo Myfieldinfoa = MyTypea.GetField("field",
BindingFlags.Public | BindingFlags.Instance);
Type MyTypeb = typeof(Myfieldb);
FieldInfo Myfieldinfob = MyTypeb.GetField("field",
BindingFlags.Public | BindingFlags.Instance);
//Modify the fields.
//Note that Myfieldb is not modified, as it is
//read-only (IsInitOnly is True).
Myfielda.field = "A - modified";
//Myfieldb.field = "B - modified";
//For the first field, get and display the name, field, and IsInitOnly state.
Console.Write("\n{0} - {1}, IsInitOnly = {2} ",
MyTypea.FullName,
Myfieldinfoa.GetValue(Myfielda),
Myfieldinfoa.IsInitOnly);
//For the second field get and display the name, field, and IsInitOnly state.
Console.Write("\n{0} - {1}, IsInitOnly = {2} ",
MyTypeb.FullName,
Myfieldinfob.GetValue(Myfieldb),
Myfieldinfob.IsInitOnly);
return 0;
}
}
Imports System.Reflection
'Make two fields, one public and one read-only.
Public Class Myfielda
Public field As String = "A - public modifiable field"
End Class
Public Class Myfieldb
Public ReadOnly field As String = "B - readonly field"
End Class
Public Class Myfieldinfo
Public Shared Function Main() As Integer
Console.WriteLine("Reflection.FieldInfo")
Console.WriteLine()
Dim Myfielda As New Myfielda()
Dim Myfieldb As New Myfieldb()
'Get the Type and FieldInfo.
Dim MyTypea As Type = GetType(Myfielda)
Dim Myfieldinfoa As FieldInfo = MyTypea.GetField("field", _
BindingFlags.Public Or BindingFlags.Instance)
Dim MyTypeb As Type = GetType(Myfieldb)
Dim Myfieldinfob As FieldInfo = MyTypeb.GetField("field", _
BindingFlags.Public Or BindingFlags.Instance)
'Modify the fields.
'Note that Myfieldb is not modified, as it is
'read-only (IsInitOnly is True).
Myfielda.field = "A - modified"
'For the first field, get and display the name, field, and IsInitOnly state.
Console.WriteLine("{0} - {1}, IsInitOnly = {2} ", MyTypea.FullName, _
Myfieldinfoa.GetValue(Myfielda), Myfieldinfoa.IsInitOnly)
'For the second field get and display the name, field, and IsInitOnly state.
Console.WriteLine("{0} - {1}, IsInitOnly = {2} ", MyTypeb.FullName, _
Myfieldinfob.GetValue(Myfieldb), Myfieldinfob.IsInitOnly)
Return 0
End Function 'Main
End Class
このコードを実行すると、次の出力が生成されます。
Reflection.FieldInfo
Myfielda - A- modified, IsInitOnly = False
Myfieldb - B readonly field, IsInitOnly = True
注釈
戻り値が指定されている場合、フィールドは true初期化のみ可能で、その後は読み取り専用です。
プロパティを取得するには、最初に IsInitOnly クラス Typeを取得します。 から 、 Typeを取得します FieldInfo。 FieldInfoから、プロパティを取得しますIsInitOnly。 パブリック以外のフィールドにアクセスするには、メソッドの一方または両方BindingFlags.StaticとBindingFlags.InstanceGetField組み合わせますBindingFlags.NonPublic。
このプロパティは IsInitOnly 、属性が FieldAttributes.InitOnly 設定されるときに設定されます。