Functional / lambda

This new version enforces the use of Serializable{Predicate,Function,Supplier}2 classes where we previously use Serializable* variants. This is also enforced in our custom wicket components methods.

The purpose of this move is :

• To explicitly state in codebase the Serializable constraint when it is needed by wicket page persistence model.

• To build types that enable both guava, java.util and Serializable contracts and so that they can be used easily with all these API.

• To implement once and consistently all the needed composition methods (for SerializablePredicate2, it is needed to override and(), or(), … to enforce Serializable contract on generated Predicate).

To ease the transition, the following mechanisms can be used:

• This script allow to track all package/class renaming involved.

  #! /bin/bash
  
  while read line; do
  find -name '*.java' -exec perl -i -pe "$line" {} ';'
  done <<EOF
  s/\\\Qorg.iglooproject.commons.util.functional/org.iglooproject.functional/g
  s/SerializableFunction(?!2)/SerializableFunction2/g
  s/SerializablePredicate(?!2)/SerializablePredicate2/g
  s/SerializableSupplier(?!2)/SerializableSupplier2/g
  EOF
  

• For @FunctionalInterface s, dynamic casting allow to obtain the new types. (beware that lambda must involve only Serializable objects).

• Helpers in {Predicate,Function,Supplier}s2 allow to transform existing objects to the targetted type.

For an already working codebase, your {Predicate,Function,Supplier} used by wicket are surely Serializable, even if not explicitly enforced by type declaration, so it is safe to use provided helpers to wrap them to a {Predicate,Function,Supplier}2 instance.