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# PassthroughSubject

A subject that broadcasts elements to downstream subscribers.

```
final class PassthroughSubject<Output, Failure> where Failure : Error
```

## Overview

As a concrete implementation of [`Subject`](/documentation/Combine/Subject), the [`PassthroughSubject`](/documentation/Combine/PassthroughSubject) provides a convenient way to adapt existing imperative code to the Combine model.

Unlike [`CurrentValueSubject`](/documentation/Combine/CurrentValueSubject), a [`PassthroughSubject`](/documentation/Combine/PassthroughSubject) doesn’t have an initial value or a buffer of the most recently-published element.
A [`PassthroughSubject`](/documentation/Combine/PassthroughSubject) drops values if there are no subscribers, or its current demand is zero.

## Topics

### Creating a passthrough subject

[`init()`](/documentation/Combine/PassthroughSubject/init())


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