# ImplicitChannelSubscriptionAttribute.ImplicitChannelSubscriptionAttribute(IChannelNamespacePredicate, string?)

[Type overview](/orleans/docs/api/csharp/microsoft.orleans.broadcastchannel/orleans.implicitchannelsubscriptionattribute/) | [Constructors](/orleans/docs/api/csharp/microsoft.orleans.broadcastchannel/orleans.implicitchannelsubscriptionattribute/constructors/)

[Source](https://github.com/dotnet/orleans/blob/b7a9e3e1c9c54b3cec3a467c5734bf7744541bcf/src/Orleans.BroadcastChannel/SubscriberTable/Predicates/ImplicitChannelSubscriptionAttribute.cs#L64-L68)

```csharp
public ImplicitChannelSubscriptionAttribute(IChannelNamespacePredicate predicate, string? channelIdMapper = null)
```

Allows to pass an instance of the stream namespace predicate. To be used mainly as an extensibility point via inheriting attributes.

### Parameters

- `predicate` (`IChannelNamespacePredicate`): The stream namespace predicate.
- `channelIdMapper` (`string?`): The name of the stream identity mapper.