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{{#title std::unique_ptr<T> — Rust ♡ C++}}
# std::unique\_ptr\<T\>
The Rust binding of std::unique\_ptr\<T\> is called **[`UniquePtr<T>`]**. See
the link for documentation of the Rust API.
[`UniquePtr<T>`]: https://docs.rs/cxx/*/cxx/struct.UniquePtr.html
### Restrictions:
Only `std::unique_ptr<T, std::default_delete<T>>` is currently supported. Custom
deleters may be supported in the future.
UniquePtr\<T\> does not support T being an opaque Rust type. You should use a
Box\<T\> (C++ [rust::Box\<T\>](box.md)) instead for transferring ownership of
opaque Rust types on the language boundary.
## Example
UniquePtr is commonly useful for returning opaque C++ objects to Rust. This use
case was featured in the [*blobstore tutorial*](../tutorial.md).
```rust,noplayground
// src/main.rs
#[cxx::bridge]
mod ffi {
unsafe extern "C++" {
include!("example/include/blobstore.h");
type BlobstoreClient;
fn new_blobstore_client() -> UniquePtr<BlobstoreClient>;
// ...
}
}
fn main() {
let client = ffi::new_blobstore_client();
// ...
}
```
```cpp
// include/blobstore.h
#pragma once
#include <memory>
class BlobstoreClient;
std::unique_ptr<BlobstoreClient> new_blobstore_client();
```
```cpp
// src/blobstore.cc
#include "example/include/blobstore.h"
std::unique_ptr<BlobstoreClient> new_blobstore_client() {
return std::make_unique<BlobstoreClient>();
}
```
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