```

then it is a "callable".

## Classes as dependencies { #classes-as-dependencies_1 }

You might notice that to create an instance of a Python class, you use that same syntax.

For example:

```Python
class Cat:
    def __init__(self, name: str):
        self.name = name


fluffy = Cat(name="Mr Fluffy")
```

In this case, `fluffy` is an instance of the class `Cat`.

Nesse caso,  `fluffy` é uma instância da classe `Cat`.

E para criar `fluffy`, você está "chamando" `Cat`.

Então, uma classe Python também é "chamável".

Então, no **FastAPI**, você pode utilizar uma classe Python como uma dependência.

O que o FastAPI realmente verifica, é se a dependência é algo chamável (função, classe, ou outra coisa) e os parâmetros que foram definidos.

## Klassen als Abhängigkeiten { #classes-as-dependencies_1 }

Möglicherweise stellen Sie fest, dass Sie zum Erstellen einer Instanz einer Python-Klasse die gleiche Syntax verwenden.

Zum Beispiel:

```Python
class Cat:
    def __init__(self, name: str):
        self.name = name


fluffy = Cat(name="Mr Fluffy")
```

In diesem Fall ist `fluffy` eine Instanz der Klasse `Cat`.

            classes[it.simpleName] = c
        }
        [OldBase, OldSub, NewBase, NewSub].each {
            classes[it.simpleName] = instanceScopedPool.get(it.name)
        }

        classes['OldBase'].superclass = classes['OldSuperInternal']
        classes['NewBase'].superclass = classes['NewSuperInternal']
        classes['OldSub'].superclass = classes['OldBase']

  private static Class<? extends Annotation> asAnnotation(Class<?> clazz) {
    if (clazz.isAnnotation()) {
      return (Class<? extends Annotation>) clazz;
    } else {
      throw new IllegalArgumentException(rootLocaleFormat("%s is not an annotation.", clazz));
    }
  }

  public void testFeatureEnums() throws Exception {
    assertGoodFeatureEnum(CollectionFeature.class);
    assertGoodFeatureEnum(ListFeature.class);

```

entonces es un "callable".

## Clases como dependencias { #classes-as-dependencies_1 }

Puedes notar que para crear una instance de una clase en Python, utilizas esa misma sintaxis.

Por ejemplo:

```Python
class Cat:
    def __init__(self, name: str):
        self.name = name


fluffy = Cat(name="Mr Fluffy")
```

En este caso, `fluffy` es una instance de la clase `Cat`.

And an `APIRoute` subclass to use that custom request class.

### Create a custom `GzipRequest` class { #create-a-custom-gziprequest-class }

/// tip

This is a toy example to demonstrate how it works, if you need Gzip support, you can use the provided [`GzipMiddleware`](../advanced/middleware.md#gzipmiddleware){.internal-link target=_blank}.

///

```Python
something(some_argument, some_keyword_argument="foo")
```

в таком случае он является «вызываемым».

## Классы как зависимости { #classes-as-dependencies_1 }

Вы можете заметить, что для создания экземпляра класса в Python используется тот же синтаксис.

Например:

```Python
class Cat:
    def __init__(self, name: str):
        self.name = name


fluffy = Cat(name="Mr Fluffy")
```

WebSocketErrorModel: type[BaseModel] = create_model("WebSocket")


class FastAPIError(RuntimeError):
    """
    A generic, FastAPI-specific error.
    """


class DependencyScopeError(FastAPIError):
    """
    A dependency declared that it depends on another dependency with an invalid
    (narrower) scope.
    """


class ValidationException(Exception):
    def __init__(
        self,

## Instalación { #installation }

Crea y activa un <a href="https://fastapi.tiangolo.com/es/virtual-environments/" class="external-link" target="_blank">entorno virtual</a> y luego instala FastAPI:

<div class="termy">

```console
$ pip install "fastapi[standard]"

---> 100%
```

</div>