///

## 🆎 🔑 **FastAPI**

**FastAPI** ✊ 📈 👫 🆎 🔑 📚 👜.

⏮️ **FastAPI** 👆 📣 🔢 ⏮️ 🆎 🔑 & 👆 🤚:

* **👨‍🎨 🐕‍🦺**.
* **🆎 ✅**.

...and **FastAPI** uses the same declarations :

* **🔬 📄**: ⚪️➡️ 📨 ➡ 🔢, 🔢 🔢, 🎚, 💪, 🔗, ♒️.
* **🗜 💽**: ⚪️➡️ 📨 🚚 🆎.
* **✔ 💽**: 👟 ⚪️➡️ 🔠 📨:
    * 🏭 **🏧 ❌** 📨 👩‍💻 🕐❔ 📊 ❌.
* **📄** 🛠️ ⚙️ 🗄:
    * ❔ ⤴️ ⚙️ 🏧 🎓 🧾 👩‍💻 🔢.

  /*
   * This class maintains a lazily-initialized table of atomically
   * updated variables, plus an extra "base" field. The table size
   * is a power of two. Indexing uses masked per-thread hash codes.
   * Nearly all declarations in this class are package-private,
   * accessed directly by subclasses.
   *
   * Table entries are of class Cell; a variant of AtomicLong padded
   * to reduce cache contention on most processors. Padding is

    @SuppressWarnings("nullness")
    Object[] result = ObjectArrays.toArrayImpl(this);
    return result;
  }

  @Override
  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
  public <T extends @Nullable Object> T[] toArray(T[] other) {
    return ObjectArrays.toArrayImpl(this, other);
  }

  @Override
  public boolean contains(@Nullable Object object) {
    try {

   * explicit {@code @NullableDecl} annotation (see <a
   * href="https://github.com/google/guava/issues/1819">#1819</a>).
   *
   * <p>It is not necessary to consider visibility, return type, or type parameter declarations. The
   * declaration of a method with the same name and formal parameters as {@link Object#equals} that
   * is not public and boolean-returning, or that declares any type parameters, would be rejected at
   * compile-time.
   */

**FastAPI** takes advantage of these type hints to do several things.

With **FastAPI** you declare parameters with type hints and you get:

* **Editor support**.
* **Type checks**.

...and **FastAPI** uses the same declarations to:

* **Define requirements**: from request path parameters, query parameters, headers, bodies, dependencies, etc.
* **Convert data**: from the request to the required type.
* **Validate data**: coming from each request:

      // creating an ArrayList so filtering happens once
      return Lists.newArrayList(iterator()).toArray();
    }

    @Override
    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
    public <T extends @Nullable Object> T[] toArray(T[] array) {
      return Lists.newArrayList(iterator()).toArray(array);
    }
  }

  /**

   * explicit {@code @Nullable} annotation (see <a
   * href="https://github.com/google/guava/issues/1819">#1819</a>).
   *
   * <p>It is not necessary to consider visibility, return type, or type parameter declarations. The
   * declaration of a method with the same name and formal parameters as {@link Object#equals} that
   * is not public and boolean-returning, or that declares any type parameters, would be rejected at
   * compile-time.
   */

    return toArray(EMPTY_ARRAY);
  }

  @CanIgnoreReturnValue
  @Override
  /*
   * This suppression is here for two reasons:
   *
   * 1. b/192354773 in our checker affects toArray declarations.
   *
   * 2. `other[size] = null` is unsound. We could "fix" this by requiring callers to pass in an
   * array with a nullable element type. But probably they usually want an array with a non-nullable

     * non-reified type or has bounds, {@code forDependants} is used to do further resolution, which
     * doesn't try to resolve any type variable on generic declarations that are already being
     * resolved.
     *
     * <p>Should only be called and overridden by {@link #resolve(TypeVariable)}.
     */
    Type resolveInternal(TypeVariable<?> var, TypeTable forDependants) {

This actually inspired updating parts of Pydantic, to support the same validation declaration style (all this functionality is now already available in Pydantic).

///

### <a href="https://github.com/hugapi/hug" class="external-link" target="_blank">Hug</a>

Hug was one of the first frameworks to implement the declaration of API parameter types using Python type hints. This was a great idea that inspired other tools to do the same.