Jens Melgaard created LUCENENET-515:
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Summary: bring back TokenStream.GetAttribute(Type).
Key: LUCENENET-515
URL: https://issues.apache.org/jira/browse/LUCENENET-515
Project: Lucene.Net
Issue Type: Improvement
Components: Lucene.Net Core
Affects Versions: Lucene.Net 3.0.3
Reporter: Jens Melgaard
I Have noticed that TokenStream.GetAttribute(Type) is gone in favor for
TokenStream.GetAttribute<Type>();
Obviously TokenStream.GetAttribute<Type>(); but it should not replace
TokenStream.GetAttribute(Type), but instead compliment it... But this is a
common pitfall, especially for non-.NET developers and people who have not run
into the implications of this..
In the case of Lucene.NET, it is properly unlikely that this will affect
anyone, however, I consider what has been done bad practice... now why is that?
Many would think like this:
Before I had to do this old thing...
TokenStream.GetAttribute(typeof(TermAttribute));
And god I hated that, so now I replaced it with the much more beautiful:
TokenStream.GetAttribute<TermAttribute>();
And deleted that old hag of a method taking a Type... And now I am happy...
BUT!...
What when...
Type myNotDefinedHereType = GetTypeFromSomeWhere();
TokenSteam.GetAttribute.... ?????!?!?!?... Uhm... What now????
Now you have to write a whole lot of reflection mess, use a dynamically
compiled delegate using IL-Emit or the Mono Compiler as a Service...
All of those 3 workarounds are generally just ugly...
If you keept both...
Type myNotDefinedHereType = GetTypeFromSomeWhere();
TokenSteam.GetAttribute(myNotDefinedHereType);
While it might be unlikely that it will ever be used, there is always the off
case, and API's should support both...
So instead of:
public virtual T GetAttribute<T>() where T : IAttribute
{
Type key = typeof (T);
if (!this.attributes.ContainsKey(key))
throw new ArgumentException("This AttributeSource does not have the
attribute '" + key.FullName + "'.");
else
return (T) this.attributes[key].Value;
}
Do:
public virtual T GetAttribute<T>() where T : IAttribute
{
return (T) GetAttribute(typeof(T));
}
public virtual IAttribute GetAttribute(Type key)
{
//Note: Since Type is required to implement IAttribute, I would properly
check that as well to be able to provide a more meaningfull error... However to
speed things up, I would do it inside the if bellow...
if (!this.attributes.ContainsKey(key))
throw new ArgumentException("This AttributeSource does not have the
attribute '" + key.FullName + "'.");
else
return (T) this.attributes[key].Value;
}
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