FieldInfo.IsInitOnly Свойство
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Возвращает значение, которое определяет, устанавливается ли поле только в тексте сообщения конструктора.
public:
property bool IsInitOnly { bool get(); };
public bool IsInitOnly { get; }
member this.IsInitOnly : bool
Public ReadOnly Property IsInitOnly As Boolean
Значение true
, если для поля задан атрибут InitOnly
, в противном случае — значение false
.
В следующем примере создаются два поля. Второе поле доступно только для чтения, не имеет метода доступа set и IsInitOnly
имеет значение true
.
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
Этот код выводит следующие результаты:
Reflection.FieldInfo
Myfielda - A- modified, IsInitOnly = False
Myfieldb - B readonly field, IsInitOnly = True
Если возвращаемое значение равно true
, поле можно инициализировать только и после этого будет доступно только для чтения.
Чтобы получить IsInitOnly
свойство , сначала получите класс Type
.
Type
Из получите FieldInfo
.
FieldInfo
Из получите IsInitOnly
свойство . Чтобы получить доступ к не открытому полю, комбинируйте BindingFlags.NonPublic с или обоими из BindingFlags.Static и BindingFlags.Instance в методе GetField
.
Свойство IsInitOnly
задается при установке атрибута FieldAttributes.InitOnly .
Продукт | Версии |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1 |
UWP | 10.0 |
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