## Uma instância "chamável"

Em Python existe uma maneira de fazer com que uma instância de uma classe seja um "chamável".

Não propriamente a classe (que já é um chamável), mas a instância desta classe.

Para fazer isso, nós declaramos o método `__call__`:

{* ../../docs_src/dependencies/tutorial011_an_py39.py hl[12] *}

        buf.append(cpSeparator);
        // WEB-INF/classes
        buf.append("WEB-INF");
        buf.append(File.separator);
        buf.append("classes");
        // target/classes
        final String userDir = System.getProperty("user.dir");
        final File targetDir = new File(userDir, "target");
        final File targetClassesDir = new File(targetDir, "classes");
        if (targetClassesDir.isDirectory()) {

        buf.append(cpSeparator);
        // WEB-INF/classes
        buf.append("WEB-INF");
        buf.append(File.separator);
        buf.append("classes");
        // target/classes
        final String userDir = System.getProperty("user.dir");
        final File targetDir = new File(userDir, "target");
        final File targetClassesDir = new File(targetDir, "classes");
        if (targetClassesDir.isDirectory()) {

`Query`, `Path` e outras classes que você verá a frente são subclasses de uma classe comum `Param`.

Todas elas compartilham os mesmos parâmetros para validação adicional e metadados que você viu.

///

/// note | Detalhes Técnicos

Quando você importa `Query`, `Path` e outras de `fastapi`, elas são na verdade funções.

Que quando chamadas, retornam instâncias de classes de mesmo nome.

 *   <li>{@link Stopwatch}
 *   <li>{@link Throwables}
 *   <li>{@link Verify}
 * </ul>
 *
 * <h3>The rest</h3>
 *
 * This package also contains some classes with niche use cases (e.g., {@link Utf8} and {@link
 * Defaults}), as well as a number of classes that have been superseded by additions to the JDK.
 */
@CheckReturnValue
@NullMarked
package com.google.common.base;

# Custom Response Classes - File, HTML, Redirect, Streaming, etc.

There are several custom response classes you can use to create an instance and return them directly from your *path operations*.

Read more about it in the [FastAPI docs for Custom Response - HTML, Stream, File, others](https://fastapi.tiangolo.com/advanced/custom-response/).

You can import them directly from `fastapi.responses`:

```python
from fastapi.responses import (
    FileResponse,

            <phase>process-classes</phase>
            <goals>
              <goal>manifest</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <instructions>
            <!-- Silence a warning that claims that META-INF/versions/9/... is the "wrong directory" for our classes. -->
            <_fixupmessages>^Classes found in the wrong directory: .*</_fixupmessages>

    String concurrentPackage = SettableFuture.class.getPackage().getName();
    ClassLoader classLoader = AggregateFutureStateFallbackAtomicHelperTest.class.getClassLoader();
    // we delegate to the current classloader so both loaders agree on classes like TestCase
    return new URLClassLoader(ClassPathUtil.getClassPathUrls(), classLoader) {
      @Override
      public Class<?> loadClass(String name) throws ClassNotFoundException {

 * implementing new escapers. It is strongly recommended that when implementing a new escaper you
 * extend one of these classes. If you find that you are unable to achieve the desired behavior
 * using either of these classes, please contact the Java libraries team for advice.
 *
 * <p>Popular escapers are defined as constants in classes like {@link
 * com.google.common.html.HtmlEscapers} and {@link com.google.common.xml.XmlEscapers}. To create

    String concurrentPackage = SettableFuture.class.getPackage().getName();
    ClassLoader classLoader = AbstractFutureFallbackAtomicHelperTest.class.getClassLoader();
    // we delegate to the current classloader so both loaders agree on classes like TestCase
    return new URLClassLoader(ClassPathUtil.getClassPathUrls(), classLoader) {
      @Override
      public Class<?> loadClass(String name) throws ClassNotFoundException {