How do you dynamically create & initialise arbitrary objects?

Question

I need to load settings from a file the file is essentially xml - each 'setting' is an element and has attributes ( name  type & value ). I loop through each 'setting' and need to create objects accordingly. How do I dynamically create objects of the type specified by each 'setting' and initialise them to the specified value ?

graeme · Answer

This is what I have so far: Example: The file tells me there is a setting named 'Setting1' it is of type 'System.Int32' and the value is '1'. I can get a Type object as I have the fully qualified type name (System.Int32) and I have the value that the object should ultimately have (1) - although this is in String form. In this instance I need a way of instantiating an int object and setting it's value to 1 - this method must however work for any type - I don't want to have to code tests for every conceivable type for example: if ( typeNameStr.Equals( typeof( int ).FullName ) ) { ob = int.Parse( typeValueStr ); } else if ( typeNameStr.Equals( typeof( decimal ).FullName ) ) { ob = decimal.Parse( typeValueStr ); } else if ( typeNameStr.Equals( typeof( double ).FullName ) ) { ob = double.Parse( typeValueStr ); } else if....

Nilanka Dharmadasa · Answer

OK. If you store the settings temporily as strings then you may have to use a method like 'TryParse' to find the type of the data. Or you can temporily store the settings as Objects and use 'GetType()' method to get the type. Then you can create the objects.

graeme · Answer

Thanks that's a nifty solution - unfortunately the file I need to work with isn't strictly xml... I have to read it 'manually' which results in me having all the setting values stored temporarily as strings. From there I need to create objects (mostly primitive types like intshortdecimal) to store these values.

Nilanka Dharmadasa · Answer

Hi I will give you a simple example on this. I hope you will be able to get a very goo idea from this. Let's say this is the file 'abc.xml'. ABC 4 1 true Now we are writing the code to deserialize this xml file. [XmlRoot(MyFile)] [Serializable] public class MyFile { [XmlElement(Setting1)] public string setting1; [XmlElement(Setting2)] public int setting2; [XmlElement(Setting3)] public bool setting3; public static MyFile SelfRef { get { return selfref; } } #region Constructor static MyFile() { selfref = new MyFile(); Read(); } #endregion public static void Read() { try { XmlDocument document = new XmlDocument(); string filename = abc.xml; if (File.Exists(filename)) document.Load(filename); else return; XmlSerializer xSerializer = new XmlSerializer(typeof(MyFile)); XmlNodeReader xNodeReader = new XmlNodeReader(document.DocumentElement); selfref = (UserPreferences)xSerializer.Deserialize(xNodeReader); } catch (Exception ex) { } } } public class Setting1 { [XmlElement(name)] public string name; [XmlElement(type)] public int type; public Setting1() { } } If you have any problem please do not hesitate to ask me.