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https://issues.apache.org/jira/browse/LUCENENET-515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13527626#comment-13527626
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Michael Herndon commented on LUCENENET-515:
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TokenStream.GetAttribute(Type).
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You would, but it generally is a good idea to support both styles in
case the type is dynamically deduced for whatever reason.
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From: Simon Svensson (JIRA)
Sent: 12/7/2012 7:55 AM
To: [email protected]
Subject: [jira] [Commented] (LUCENENET-515) bring back
TokenStream.GetAttribute(Type).
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https://issues.apache.org/jira/browse/LUCENENET-515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13526351#comment-13526351
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Simon Svensson commented on LUCENENET-515:
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IAttribute is just an empty marker interface, wouldn't you still need
"a whole lot of reflection mess" to interact with it if you had an
`IAttribute GetAttribute(Type)` api?
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> 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>() is a better syntax; 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...
> {code}TokenStream.GetAttribute(typeof(TermAttribute));{code}
> And god I hated that, so now I replaced it with the much more beautiful:
> {code}TokenStream.GetAttribute<TermAttribute>();{code}
> And deleted that old hag of a method taking a Type... And now I am happy...
> BUT!...
> What when...
> {code}
> Type myNotDefinedHereType = GetTypeFromSomeWhere();
> TokenSteam.GetAttribute.... ?????!?!?!?... Uhm... What now????
> {code}
> 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...
> {code}
> Type myNotDefinedHereType = GetTypeFromSomeWhere();
> TokenSteam.GetAttribute(myNotDefinedHereType);
> {code}
> 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:
> {code}
> 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;
> }
> {code}
> Do:
> {code}
> public 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;
> }
> {code}
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