Add some attributes

Author: kristiker

Attributes.cs

@@ -24,7 +24,7 @@ class Attribute
         /// <param name="value">The value of the Attribute, which must be of a supported Datamodel type.</param>
         public Attribute(string name, AttributeList owner, object value)
         {
-            ArgumentNullException.ThrowIfNull(name); 
+            ArgumentNullException.ThrowIfNull(name);
 
             Name = name;
             _Owner = owner;

Element.cs

@@ -29,14 +29,13 @@ public class Element : AttributeList, INotifyPropertyChanged, ISupportInitialize
         /// <param name="name">An arbitrary string. Does not have to be unique, and can be null.</param>
         /// <param name="class_name">An arbitrary string which loosely defines the type of Element this is. Cannot be null.</param>
         /// <exception cref="IndexOutOfRangeException">Thrown when the owner already contains the maximum number of Elements allowed in a Datamodel.</exception>
-        public Element(Datamodel owner, string name, Guid? id = null, string class_name = "DmElement")
+        public Element(Datamodel owner, string name, Guid? id = null, string classNameOverride = null)
             : base(owner)
         {
             ArgumentNullException.ThrowIfNull(owner);
-            ArgumentNullException.ThrowIfNull(class_name);
-            
+
             Name = name;
-            ClassName = class_name;
+            ClassName = classNameOverride ?? GetType().Name;
 
             if (id.HasValue)
                 _ID = id.Value;

Format/Attribute.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace Datamodel.Format;
+
+/// <summary>
+/// Subclass this attribute to define a custom attribute name convention.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]
+public abstract class AttributeNameConventionAttribute : System.Attribute
+{
+    public abstract string GetAttributeName(string propertyName);
+}
+
+public class AttributeNameLowercaseAttribute : AttributeNameConventionAttribute
+{
+    public override string GetAttributeName(string propertyName)
+        => propertyName.ToLower();
+}
+
+public class AttributeNameCamelCaseAttribute : AttributeNameConventionAttribute
+{
+    public override string GetAttributeName(string propertyName)
+        => char.ToLowerInvariant(propertyName.AsSpan()[0]) + propertyName[1..];
+}
+
+[AttributeUsage(AttributeTargets.Property, Inherited = true, AllowMultiple = false)]
+public sealed class Attribute : System.Attribute
+{
+    public Attribute(string name)
+    {
+        Name = name;
+    }
+
+    public string Name { get; }
+}