So many thanks for all your great help end valuable time .
i still need your help to port this code :
Code:
internal static void PrintValue(object value, Type valueType)
{
if (value == null)
{
Console.WriteLine(valueType);
return;
}
var type = value.GetType();
switch (Type.GetTypeCode(type))
{
case TypeCode.Int32: Console.WriteLine((int)value); break;
case TypeCode.Int64: Console.WriteLine((long)value); break;
case TypeCode.UInt32: Console.WriteLine((uint)value); break;
case TypeCode.UInt64: Console.WriteLine((ulong)value); break;
case TypeCode.Double: Console.WriteLine((double)value); break;
case TypeCode.String: Console.WriteLine((string)value); break;
case TypeCode.Boolean: Console.WriteLine((bool)value ? true : false); break;
case TypeCode.DateTime: Console.WriteLine((DateTime)value); break;
case TypeCode.Object:
if (type.IsArray)
if (value is byte[] bytes)
Console.WriteLine(bytes);
else if (value is Int128 int128)
Console.WriteLine(int128);
else if (value is Int256 int256)
Console.WriteLine(int256);
else if (value is IObject MyObject)
Console.WriteLine(MyObject);
else if (type.IsEnum)
Console.WriteLine((uint)value);
else
break;
default:
break;
}
}
That does not directly translate to Delphi since simple types are not objects in Delphi, so you cannot write a method that can basically take any type of value this way. Delphi has
run-time type information, though, it has support for typeless (anonymous) parameters (from which you cannot obtain the actual type of the passed values, unfortunately), it has support for Variant types ( derived from the
OLE VARIANT type), and it has TValue. Depending on how this PrintValue method is used in the C# code you are trying to translate you could probably write an analog using one of these.
For example something simple like this works for many simple types:
Delphi-Quellcode:
procedure PrintValue(const V: Variant);
begin
WriteLn(V);
end;
procedure TProcessor.TestPrintSimpleValues;
const
A: array of integer = [0,1,2,3,4];
begin
Write('Byte: '); PrintValue(Byte($80));
Write('ShortInt: '); PrintValue(ShortInt($80));
Write('Word: '); PrintValue(Word($8045));
Write('SmallInt: '); PrintValue(SmallInt($8045));
Write('Integer: '); PrintValue(Integer(-124972));
Write('Cardinal: '); PrintValue(Cardinal(124972));
Write('Single: '); PrintValue(Single(128.45));
Write('Double: '); PrintValue(Single(128.45));
Write('String: '); PrintValue('This is just text.');
Write('Array: '); PrintValue(A);
// The last one fails since a variant containing an array connot be converted to a string directly by VarToString.
end;
You can add support for other data types that can be packaged into a Variant with a
Delphi-Quellcode:
case VarType(V) of
varArray: (...);
else
WriteLn(V);
end;
inside PrintValue, but this is limited by what you can
package into a Variant in a way that allows the type of the content to be identified. The big advantage is that Delphi does the packaging at the point of call for you, inferring the type from the value or variable you pass.
Delphi-Quellcode:
procedure PrintValue2(const Value; ValueType: PTypeInfo);
begin
case ValueType^.Kind of
// ...cast Value to the correct type for WriteLn.
end;
end;
That would be the general approach using typeless parameters. In this case you need to explicitely pass the correct type information (obtained via the TypeInfo function) with the value to print and are settled with the task of converting to text for display yourself.
And finally there is TValue (System.RTTI
unit), which has a number of implicit operator methods to
package common data types into a TValue. And it has a ToString method that covers most of the conversion needs. But you may have to code some special cases yourself, like in the PrintValue2 procedure above.
Delphi-Quellcode:
procedure PrintValue3(const V: TValue);
begin
WriteLn(V.ToString);
end;
You can use this like the procedure with the Variant parameter, at least for types that can be directly converted to a TValue and for which ToString works. For anything else more work is required again to get a string from the packaged data, especially for objects or records. It can be done but it's a lot of work...