// TODO:srcM.Changing can fail after our Changing is done.
// For example, if another subsciber is called after this and it cancels the update.
// Then the target will have the entry, this one - doesn't.
private void MetadataChanging(object sender, VariableMetadataChangingEventArgs e)
{
if (IsReadOnlyEntry(e.Key))
{
e.Cancel = true;
return;
}
if (!IsHiddenEntry(e.Key))
{
if (proposedMetadataEntries.Exists(entry =>
entry.Key == e.Key && AreEquals(entry.Value, e.ProposedValue)))
{
return;
}
var pair = new KeyValuePair <string, object>(e.Key, e.ProposedValue);
try
{
proposedMetadataEntries.Add(pair);
target.Metadata[e.Key] = e.ProposedValue;
}
finally
{
proposedMetadataEntries.Remove(pair);
}
}
}
/// <summary>
/// Gets the metadata value or sets new value for the given key.
/// </summary>
/// <param name="key">The name of the metadata attribute to get.</param>
/// <returns>Value corresponding to the given key.</returns>
/// <remarks>
/// <para>
/// The indexer returns committed values.
/// See remarks for <see cref="this[string, SchemaVersion]"/>.
/// </para>
/// </remarks>
/// <seealso cref="this[string, SchemaVersion]"/>
/// <seealso cref="SchemaVersion"/>
/// <seealso cref="Variable"/>
public virtual object this[string key]
{
get
{
return(this[key, SchemaVersion.Committed]);
}
set
{
if (readOnly)
{
throw new Exception("MetadataDictionary is read only");
}
CheckKey(key);
CheckValue(value);
// Constraints on name
if (key == KeyForName)
{
if (value != null && !(value is string))
{
throw new Exception("Name of a variable must be a string");
}
}
object old = null;
object cloneValue = null;
if (value is ICloneable)
{
cloneValue = ((ICloneable)value).Clone();
}
else
{
cloneValue = value;
}
bool changed = true;
if (HasChanges)
{
if (modified.ContainsKey(key))
{
old = modified[key];
changed = !AreEquals(old, cloneValue);
}
else if (dictionary.ContainsKey(key))
{
old = dictionary[key];
changed = !AreEquals(old, cloneValue);
}
}
else if (dictionary.ContainsKey(key))
{
changed = !AreEquals(old = dictionary[key], cloneValue);
}
if (!changed)
{
return;
}
VariableMetadataChangingEventArgs e = new VariableMetadataChangingEventArgs(
key, cloneValue, old);
if (Changing != null)
{
Changing(this, e);
if (e.Cancel)
{
throw new Exception("Metadata changing is cancelled.");
}
}
if (modified == null)
{
modified = new Dictionary <string, object>();
}
modified[key] = e.ProposedValue;
if (Changed != null)
{
Changed(this, new VariableMetadataChangedEventArgs(key, e.ProposedValue));
}
}
}