# ImplicitStreamSubscriptionAttribute.ImplicitStreamSubscriptionAttribute(IStreamNamespacePredicate, string)

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

[Source](https://github.com/dotnet/orleans/blob/e4e752cedecc2976811db49802c7a999b1f1c704/src/Orleans.Streaming/Predicates/StreamSubscriptionAttributes.cs#L68-L72)

```csharp
public ImplicitStreamSubscriptionAttribute(IStreamNamespacePredicate predicate, string streamIdMapper = null)
```

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

### Parameters

- `predicate` (`IStreamNamespacePredicate`): The stream namespace predicate.
- `streamIdMapper` (`string`): The name of the stream identity mapper.