## Context Managers { #context-managers }

### What are "Context Managers" { #what-are-context-managers }

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Comparator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;

/**
 * A {@link ListMultimap} whose contents will never change, with many other important properties

Entonces podemos usar la dependencia con:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[23] *}

/// info | Información

Fíjate que solo estamos declarando una dependencia en la *path operation function*, `query_or_cookie_extractor`.

Pero **FastAPI** sabrá que tiene que resolver `query_extractor` primero, para pasar los resultados de eso a `query_or_cookie_extractor` al llamarlo.

///

```mermaid
graph TB

    (For example, a function in a library to compute square roots has
    a purpose that is entirely well-defined independent of the
    application.  Therefore, Subsection 2d requires that any
    application-supplied function or table used by this function must
    be optional: if the application does not supply it, the square
    root function must still compute square roots.)

import static java.lang.Long.rotateRight;

import com.google.common.annotations.VisibleForTesting;

/**
 * Implementation of Geoff Pike's fingerprint2011 hash function. See {@link Hashing#fingerprint2011}
 * for information on the behaviour of the algorithm.
 *
 * <p>On Intel Core2 2.66, on 1000 bytes, fingerprint2011 takes 0.9 microseconds compared to

import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.SortedMap;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import org.jspecify.annotations.Nullable;

/**

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Collection;
import java.util.Comparator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;

/**
 * A {@link ListMultimap} whose contents will never change, with many other important properties

import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.BiFunction;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import java.util.stream.Collectors;
import org.jspecify.annotations.Nullable;

/**

          && method.getParameterTypes().length != 0 // only the seeded hash functions
          && !method.getName().equals("concatenating") // don't test Hashing.concatenating()
          && !method.getName().equals("goodFastHash") // tested in testGoodFastHashEquals
          && !method.getName().startsWith("hmac")) { // skip hmac functions
        Object[] params1 = new Object[method.getParameterTypes().length];

-  extern __typeof (name) aliasname __attribute__ ((alias (#name)));
+  extern __typeof (name) aliasname __attribute__ ((alias (#name))) \
+    __attribute_copy__ (name);
 
 /* This comes between the return type and function name in
    a function definition to make that definition weak.  */
@@ -125,14 +131,16 @@
    If weak aliases are not available, this defines a strong alias.  */
 # define weak_alias(name, aliasname) _weak_alias (name, aliasname)