# Introduction aux Types Python

Python supporte des annotations de type (ou *type hints*) optionnelles.

Ces annotations de type constituent une syntaxe spéciale qui permet de déclarer le <abbr title="par exemple : str, int, float, bool">type</abbr> d'une variable.

En déclarant les types de vos variables, cela permet aux différents outils comme les éditeurs de texte d'offrir un meilleur support.

Todo **FastAPI** está basado en estos type hints, lo que le da muchas ventajas y beneficios.

Pero, así nunca uses **FastAPI** te beneficiarás de aprender un poco sobre los type hints.

!!! note "Nota"
    Si eres un experto en Python y ya lo sabes todo sobre los type hints, salta al siguiente capítulo.

<img src="/img/python-types/image02.png">

Com isso, você pode rolar, vendo as opções, até encontrar o que "toca uma campainha":

<img src="/img/python-types/image03.png">

## Mais motivação

Marque esta função, ela já possui type hints:

```Python hl_lines="1"
{!../../../docs_src/python_types/tutorial003.py!}
```

}

type metricValue struct {
	Labels map[string]string
	Value  float64
}

// MetricValues - type to set metric values retrieved while loading metrics. A
// value of this type is passed to the `MetricsLoaderFn`.
type MetricValues struct {
	values      map[MetricName][]metricValue
	descriptors map[MetricName]MetricDescriptor
}

func newMetricValues(d map[MetricName]MetricDescriptor) MetricValues {

// Error implements Error interface
func (b BatchJobYamlErr) Error() string {
	return fmt.Sprintf("%s\n Hint: error near line: %d, col: %d", b.msg, b.line, b.col)
}

// BatchJobKV is a key-value data type which supports wildcard matching
type BatchJobKV struct {
	line, col int
	Key       string `yaml:"key" json:"key"`
	Value     string `yaml:"value" json:"value"`
}

var _ yaml.Unmarshaler = &BatchJobKV{}

// pointer, channel, func, interface, map, or slice type.
var nil Type // Type must be a pointer, channel, func, interface, map, or slice type

// Type is here for the purposes of documentation only. It is a stand-in
// for any Go type, but represents the same type for any given function
// invocation.
type Type int

// Type1 is here for the purposes of documentation only. It is a stand-in

import kotlin.reflect.KClass
import kotlin.reflect.KType

internal fun SmartPrinter.printTypeWithShortNames(type: KType, shouldRenderFqName: (KType) -> Boolean = { false }) {
    fun typeConversion(type: KType): String {
        val nullableSuffix = if (type.isMarkedNullable) "?" else ""
        val simpleName = if (shouldRenderFqName(type)) {
            type.qualifiedName
        } else {
            type.simpleName
        }

    }

    override fun convertType(type: KType): KType {
        val first = type.arguments.getOrNull(0)?.type ?: return type
        val second = type.arguments.getOrNull(1)?.type ?: return type
        return Pair::class.createType(
            arguments = listOf(
                KTypeProjection(
                    variance = KVariance.INVARIANT,
                    type = mappingConversionFirst.convertType(first)

		}
	}
}

// Type returns a *Type with the same memory layout as
// dtype when used as the type of a variable or a struct field.
func (c *typeConv) Type(dtype dwarf.Type, pos token.Pos) *Type {
	return c.loadType(dtype, pos, "")
}

// loadType recursively loads the requested dtype and its dependency graph.
func (c *typeConv) loadType(dtype dwarf.Type, pos token.Pos, parent string) *Type {

import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Target({FIELD, METHOD, TYPE})
@Retention(RUNTIME)
@Documented
public @interface Typed {
    Class<?>[] value() default {};