This is very useful when you need to:

* Have shared logic (the same code logic again and again).
* Share database connections.
* Enforce security, authentication, role requirements, etc.
* And many other things...

All these, while minimizing code repetition.

## First Steps { #first-steps }

Let's see a very simple example. It will be so simple that it is not very useful, for now.

    }
  }

  public static void main(String... args) throws Exception {
    new RequestBodyCompression().run();
  }

  /** This interceptor compresses the HTTP request body. Many webservers can't handle this! */
  static class GzipRequestInterceptor implements Interceptor {
    @Override public Response intercept(Chain chain) throws IOException {
      Request originalRequest = chain.request();

    String[] WINERR_MESSAGES = { "The operation completed successfully.", "Access is denied.",
            "No more connections can be made to this remote computer at this time because there are already as many connections as the computer can accept.",
            "The pipe state is invalid.", "All pipe instances are busy.", "The pipe is being closed.",

    String[] WINERR_MESSAGES = { "The operation completed successfully.", "Access is denied.",
            "No more connections can be made to this remote computer at this time because there are already as many connections as the computer can accept.",
            "The pipe state is invalid.", "All pipe instances are busy.", "The pipe is being closed.",
            "No process is on the other end of the pipe.", "More data is available.",

# ***** FALSE POSITIVES *****

# The Runnable type is so generic that it produces too many false positives.
TYPE java.lang.Runnable

FIELD com.google.common.base.Converter.reverse
FIELD com.google.common.collect.AbstractBiMap.EntrySet.iterator.$.entry com.google.common.collect.AbstractBiMap.EntrySet.iterator.$.next.$

## Other data types { #other-data-types }

Here are some of the additional data types you can use:

* `UUID`:
    * A standard "Universally Unique Identifier", common as an ID in many databases and systems.
    * In requests and responses will be represented as a `str`.
* `datetime.datetime`:
    * A Python `datetime.datetime`.

  }

  /**
   * A sensible implementation of {@link NavigableSet#descendingSet} in terms of the other methods
   * of {@link NavigableSet}, notably including {@link NavigableSet#descendingIterator}.
   *
   * <p>In many cases, you may wish to override {@link ForwardingNavigableSet#descendingSet} to
   * forward to this implementation or a subclass thereof.
   *
   * @since 12.0
   */

    /*
     * The entrySet() of ConcurrentHashMap, unlike that of other Map
     * implementations, supports add() under JDK8. This seems problematic, but I
     * didn't see that discussed in the review, which included many other
     * changes: https://mail.openjdk.org/pipermail/core-libs-dev/2013-May/thread.html#17367
     *
     * TODO(cpovirk): decide what the best long-term action here is: force users

 * @since 13.0
 */
@J2ktIncompatible
@GwtIncompatible
public abstract class Striped<L> {
  /**
   * If there are at least this many stripes, we assume the memory usage of a ConcurrentMap will be
   * smaller than a large array. (This assumes that in the lazy case, most stripes are unused. As
   * always, if many stripes are in use, a non-lazy striped makes more sense.)
   */
  private static final int LARGE_LAZY_CUTOFF = 1024;

All the dependencies we have seen are a fixed function or class.

But there could be cases where you want to be able to set parameters on the dependency, without having to declare many different functions or classes.

Let's imagine that we want to have a dependency that checks if the query parameter `q` contains some fixed content.

But we want to be able to parameterize that fixed content.