# 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/b7a9e3e1c9c54b3cec3a467c5734bf7744541bcf/src/Orleans.Streaming/Predicates/StreamSubscriptionAttributes.cs#L67-L71)

```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.