# Classes as Dependencies

Before diving deeper into the **Dependency Injection** system, let's upgrade the previous example.

## A `dict` from the previous example

In the previous example, we were returning a `dict` from our dependency ("dependable"):

//// tab | Python 3.10+

```Python hl_lines="9"
{!> ../../docs_src/dependencies/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="11"

                + ",path=" + this.path + ",ttl=" + this.ttl + ",expiration=" + this.expiration + ",remain="
                + ( this.expiration - System.currentTimeMillis() ) + "]";
    }


    /**
     * @return the ttl
     */
    public long getTtl () {
        return this.ttl;
    }


    /**
     * {@inheritDoc}
     *

        } else {
            req = new SmbComWrite();
            rsp = new SmbComWriteResponse();    
        }
    }

/**
 * Closes this output stream and releases any system resources associated
 * with it.
 *
 * @throws IOException if a network error occurs
 */

    public void close() throws IOException {
        file.close();
        tmp = null;
    }

/**

    private final LocalRepository repo;

    private final boolean realLocalRepo;

    public static RepositorySystemSession overlay(
            ArtifactRepository repository, RepositorySystemSession session, RepositorySystem system) {
        return overlay(repository, session);
    }

    public static RepositorySystemSession overlay(ArtifactRepository repository, RepositorySystemSession session) {

}

// EndpointConditions represents the current condition of an endpoint.
message EndpointConditions {
  // ready indicates that this endpoint is prepared to receive traffic,
  // according to whatever system is managing the endpoint. A nil value
  // indicates an unknown state. In most cases consumers should interpret this
  // unknown state as ready. For compatibility reasons, ready should never be

      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise

      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise

Here's a little bit of that history.

## Alternatives

I have been creating APIs with complex requirements for several years (Machine Learning, distributed systems, asynchronous jobs, NoSQL databases, etc), leading several teams of developers.

As part of that, I needed to investigate, test and use many alternatives.

      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise

      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise