So, a Python class is also a **callable**.

Then, in **FastAPI**, you could use a Python class as a dependency.

What FastAPI actually checks is that it is a "callable" (function, class or anything else) and the parameters defined.

If you pass a "callable" as a dependency in **FastAPI**, it will analyze the parameters for that "callable", and process them in the same way as the parameters for a *path operation function*. Including sub-dependencies.

import jakarta.annotation.Resource;

/**
 * API action for admin group management.
 * Provides RESTful API endpoints for managing user group settings in the Fess search engine.
 * Groups define user permissions and access controls for search and administrative functions.
 */
public class ApiAdminGroupAction extends FessApiAdminAction {

* `expose_headers` - Indica quaisquer cabeçalhos de resposta que devem ser disponibilizados ao navegador. O padrão é `[]`.
* `max_age` - Define um tempo máximo em segundos para os navegadores armazenarem em cache as respostas CORS. O padrão é `600`.

O middleware responde a dois tipos específicos de solicitação HTTP...

### Requisições CORS pré-voo (preflight)

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

* etc.

## Simples e Poderoso

Mesmo que o sistema hierárquico de injeção de dependência seja simples de definir e utilizar, ele ainda é bastante poderoso.

Você pode definir dependências que por sua vez definem suas próprias dependências.

    JAVACMD="$JAVA_HOME/jre/sh/java"
  else
    JAVACMD="$JAVA_HOME/bin/java"

    if [ ! -x "$JAVACMD" ] ; then
      echo "The JAVA_HOME environment variable is not defined correctly, so Apache Maven cannot be started." >&2
      echo "JAVA_HOME is set to \"$JAVA_HOME\", but \"\$JAVA_HOME/bin/java\" does not exist." >&2
      exit 1
    fi
  fi
else

import jakarta.annotation.Resource;

/**
 * API action for admin path mapping management.
 * Provides RESTful API endpoints for managing path mapping settings in the Fess search engine.
 * Path mappings define URL path transformations and redirections for crawling and indexing.
 */
public class ApiAdminPathmapAction extends FessApiAdminAction {

    private static final Logger logger = LogManager.getLogger(ApiAdminPathmapAction.class);

import jakarta.annotation.Resource;

/**
 * API action for admin related content management.
 * Provides RESTful API endpoints for managing related content settings in the Fess search engine.
 * Related content settings define content relationships and associations for search results.
 */
public class ApiAdminRelatedcontentAction extends FessApiAdminAction {

// list with an empty final value.
func ExampleScanner_emptyFinalToken() {
	// Comma-separated list; last entry is empty.
	const input = "1,2,3,4,"
	scanner := bufio.NewScanner(strings.NewReader(input))
	// Define a split function that separates on commas.
	onComma := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
		for i := 0; i < len(data); i++ {
			if data[i] == ',' {
				return i + 1, data[:i], nil
			}