diff --git a/doc/reference/python/random/random.py b/doc/reference/python/random/random.py
index 7e76182e..40a0c690 100644
--- a/doc/reference/python/random/random.py
+++ b/doc/reference/python/random/random.py
@@ -1,7 +1,7 @@
-from pytriqs.random import *
+from pytriqs.random_generator import *
 from pytriqs.plot.mpl_interface import *
 
 r = RandomGenerator("lagged_fibonacci607", 237489)
 l = []
-for i in range(10000): l += [r.rand(),]
-plt.hist(l, 30, normed=True);
+for i in range(10000): l += [r(),]
+plt.hist(l, 30, normed=True)
diff --git a/doc/reference/python/random/random.rst b/doc/reference/python/random/random.rst
index c4139f03..0bb303c0 100644
--- a/doc/reference/python/random/random.rst
+++ b/doc/reference/python/random/random.rst
@@ -1,33 +1,34 @@
 .. index:: Random number generator
 
-.. module:: pytriqs.random
+.. module:: pytriqs.random_generator
 
 .. _random_generator:
 
 Random generator class
 ======================
 
-TRIQS has a simple random number generator class called ``RandomGenerator``. It is based on boost
-just like the C++ random generator provided by TRIQS.
+TRIQS exposes to python the random number generators used in C++, 
+in the module ``RandomGenerator``. 
+The generators are the boost random generators.
 
 Usage
 -----
 
-The generator is constructed from a name and a seed::
+The generator is constructed from a name (the name of the boost generator) and a seed::
 
-  from pytriqs.random import *
+  from pytriqs.random_generator import *
   r = RandomGenerator("mt19937", 237849)
 
-A list of possible random generator names is obtained with::
+A list of available random generators is obtained with::
 
-  print available_generator_names()
+  print random_generator_names_list()
 
-Then you can either generate float number on the interval :math:`[0,1[` using
-the ``rand()`` method or integer numbers in the inverval :math:`[0,N-1]` using
-``int_rand(N)``::
+Then you can either generate float number on the interval :math:`[0,1[` 
+simply by calling the generator, or integer numbers in the inverval :math:`[0,N-1]` by calling 
+it with `N` ::
 
-  print r.rand()
-  print r.int_rand(10)
+  print r()
+  print r(10)
 
 Example
 -------
@@ -42,7 +43,7 @@ Here's a simple example showing how to use the generator.
 Complete reference
 ------------------
 
-.. autoclass:: pytriqs.random.RandomGenerator
+.. autoclass:: pytriqs.random_generator.RandomGenerator
   :members:
 
-.. autofunction:: pytriqs.random.available_generator_names
+.. autofunction:: pytriqs.random_generator.random_generator_names_list
diff --git a/pytriqs/random/__init__.py b/pytriqs/random/__init__.py
deleted file mode 100644
index ce5e631f..00000000
--- a/pytriqs/random/__init__.py
+++ /dev/null
@@ -1,5 +0,0 @@
-
-from random_generator import RandomGenerator, available_generator_names
-
-__all__ = ['RandomGenerator','available_generator_names']
-
diff --git a/pytriqs/random/random_generator.pyx b/pytriqs/random/random_generator.pyx
deleted file mode 100644
index 7d0b7878..00000000
--- a/pytriqs/random/random_generator.pyx
+++ /dev/null
@@ -1,49 +0,0 @@
-from dcomplex cimport * 
-from libcpp.string cimport string
-
-# The c++ random generator class
-# We wrap two members only
-cdef extern from "triqs/mc_tools/random_generator.hpp": 
-
-    cdef cppclass random_generator "triqs::mc_tools::random_generator":
-
-        random_generator(string, long) except +
-        double operator() () except +
-        int operator() (int) except +
-
-# This is the wrapping of the static member random_generator_names
-# It is a bit of a hack but there is no notion of ststic members in cython
-cdef extern from "triqs/mc_tools/random_generator.hpp" namespace "triqs::mc_tools::random_generator":
-
-    string random_generator_names(string) except +
-
-
-# The python RandomGenerator class
-cdef class RandomGenerator:
-
-  cdef random_generator * _c
-
-  def __init__(self, name, seed):
-    """This is a random number generator class based on boost.
-
-       :param name: (string) Name of the random number generator
-       :param seed: (int) Random number seed
-    """
-    self._c = new random_generator(name, seed)
-
-  def __dealloc__(self):
-    del self._c
-
-  def rand(self):
-    """Generate a float random number in [0,1["""
-    return self._c[0]()
-
-  def int_rand(self, N):
-    """Generate an integer random number in [0,N-1]"""
-    return self._c[0](N)
-
-# The list of generator names accessed through the static member
-def available_generator_names():
-  """Get a list of available random generator names"""
-  return random_generator_names(",").split(',')
-
diff --git a/pytriqs/random/CMakeLists.txt b/pytriqs/random_generator/CMakeLists.txt
similarity index 53%
rename from pytriqs/random/CMakeLists.txt
rename to pytriqs/random_generator/CMakeLists.txt
index 35ac5dc2..ba2ae123 100644
--- a/pytriqs/random/CMakeLists.txt
+++ b/pytriqs/random_generator/CMakeLists.txt
@@ -2,7 +2,8 @@ SET(PYTHON_SOURCES
   ${CMAKE_CURRENT_SOURCE_DIR}/__init__.py
 )
 
-install (FILES ${PYTHON_SOURCES} DESTINATION ${TRIQS_PYTHON_LIB_DEST}/random)
+install (FILES ${PYTHON_SOURCES} DESTINATION ${TRIQS_PYTHON_LIB_DEST}/random_generator)
+
+# Build C extension module 
+triqs_python_extension(random_generator random_generator)
 
-# the c++ code
-cython_module(random random_generator random)
diff --git a/pytriqs/random_generator/__init__.py b/pytriqs/random_generator/__init__.py
new file mode 100644
index 00000000..4a1b3405
--- /dev/null
+++ b/pytriqs/random_generator/__init__.py
@@ -0,0 +1,5 @@
+
+from random_generator import RandomGenerator, random_generator_names_list
+
+__all__ = ['RandomGenerator','random_generator_names_list']
+
diff --git a/pytriqs/random_generator/random_generator_desc.py b/pytriqs/random_generator/random_generator_desc.py
new file mode 100644
index 00000000..5e894928
--- /dev/null
+++ b/pytriqs/random_generator/random_generator_desc.py
@@ -0,0 +1,46 @@
+from wrap_generator import *
+
+module = module_(full_name = "pytriqs.random_generator", doc = "")
+module.add_include("<triqs/mc_tools/random_generator.hpp>")
+module.add_using("namespace triqs::mc_tools")
+# Not needed. Reorganize the hpp wrapper tool 
+module.add_include("<triqs/h5.hpp>")
+module.add_include("<triqs/arrays.hpp>")
+
+# ---------  RandomGenerator  ----------------------------------
+
+r = class_(py_type = "RandomGenerator",
+           c_type = "random_generator",
+           c_type_absolute = "triqs::mc_tools::random_generator",
+          )
+
+r.add_constructor(signature = "(std::string name, int seed)", 
+                  doc = 
+                  """
+                  This is a random number generator class based on boost.
+
+                  name Name of the random number generator
+                  seed Random number seed
+                  """)
+
+r.add_call(signature = "int(int N)", doc = """Generate an integer random number in [0,N-1]""") 
+r.add_call(signature = "double()", doc = """Generate a float random number in [0,1[""")
+ 
+module.add_class(r)
+
+# ---------   Module functions ----------------------------------
+
+module.add_function(name = "random_generator_names_list",
+                    signature = "std::vector<std::string>()",
+                    doc = """Get a list of available random generator names"""
+                    )
+
+########################
+##   Code generation
+########################
+
+if __name__ == '__main__' :
+   module.generate_code(mako_template = sys.argv[1], wrap_file = sys.argv[2])
+   module.generate_py_converter_header(mako_template = sys.argv[3], wrap_file = sys.argv[4])
+
+
diff --git a/test/triqs/utility/buffered_function.cpp b/test/triqs/utility/buffered_function.cpp
new file mode 100644
index 00000000..953c14e9
--- /dev/null
+++ b/test/triqs/utility/buffered_function.cpp
@@ -0,0 +1,37 @@
+/*******************************************************************************
+ *
+ * TRIQS: a Toolbox for Research in Interacting Quantum Systems
+ *
+ * Copyright (C) 2014 by O. Parcollet
+ *
+ * TRIQS is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later
+ * version.
+ *
+ * TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * TRIQS. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#include <triqs/utility/buffered_function.hpp>
+#include <iostream>
+
+int main(int argc, char **argv) {
+
+ // a function that generates all the square ....
+ int x = 0;
+ auto f = [x]() mutable { return x * (x++); };
+
+ // C++14 : init-capture 
+ // auto f = [x=0]() mutable { return x*(x++);};
+
+ auto gen = triqs::utility::buffered_function<double>(f, 5);
+
+ for (int u = 0; u < 22; ++u)
+  if (gen() != u * u) throw "Error";
+}
diff --git a/triqs/mc_tools/generator.hpp b/triqs/mc_tools/generator.hpp
deleted file mode 100644
index 6e29c38d..00000000
--- a/triqs/mc_tools/generator.hpp
+++ /dev/null
@@ -1,96 +0,0 @@
-//  (C) Copyright 2008-10 Lukas Gamper <gamperl -at- gmail.com>
-//                        Brigitte Surer <surerb -at- phys.ethz.ch>
-//                        Bela Bauer <bauerb -at- phys.ethz.ch>
-//
-//                        downgraded by O. Parcollet for compilation with icc11 & boost 1.45
-//
-//  Use, modification, and distribution are subject to the Boost Software 
-//  License, Version 1.0. (See at <http://www.boost.org/LICENSE_1_0.txt>.)
-
-#include <vector>
-#include <algorithm>
-#include <boost/function.hpp>
-#include <boost/ref.hpp>
-#include <boost/shared_ptr.hpp>
-#include <boost/make_shared.hpp>
-#include <boost/lambda/lambda.hpp>
-#include <boost/lambda/bind.hpp>
-#include <boost/lambda/construct.hpp>
-#include <boost/lambda/exceptions.hpp>
-
-namespace boost{
-    template<typename R> class generator {
-        public:
-            static std::size_t const buffer_size = 1000;
-            template<typename Generator> generator(Generator const & gen, std::size_t size = buffer_size)
-                : 
-                 buf(make_shared<buffer>(gen, size))
-                , cur(buf->cur)
-                , end(buf->end())
-            {}
-            inline R const operator()() {
-                if (cur == end)
-                    buf->fill();
-                return *cur++;
-            }
-            inline R const preview() {
-                if (cur == end)
-                    buf->fill();
-                return *cur;
-            }
-
-	     generator(generator<R> const & rhs)
-                : 
-                 buf(new buffer (*rhs.buf))
-                , cur(buf->cur)
-                , end(buf->end())
-            {} 
-            generator<R> & operator=(generator<R> rhs) {
-                swap(*this, rhs);
-                return *this;
-            }
-        private:
-            class buffer: public std::vector<R> {
-                public:
-                     friend class generator<R>;
-                    template<typename Generator> buffer(Generator const & gen, std::size_t size)
-                        : std::vector<R>(size)
-                        , engine(make_shared<Generator>(gen))
-                        , cur(this->end())
-                        , fill_helper(lambda::bind(std::generate<typename buffer::iterator, Generator &>, lambda::_1, lambda::_2, ref(*reinterpret_cast<Generator *>(engine.get()))))
-                        , clone(lambda::bind(buffer::template type_keeper<Generator>, lambda::_1, lambda::_2))
-                    {}
-                    template<typename Generator> buffer(reference_wrapper<Generator> gen, std::size_t size)
-                        : std::vector<R>(size)
-                        , cur(this->end())
-                        , fill_helper(lambda::bind(std::generate<typename buffer::iterator, Generator &>, lambda::_1, lambda::_2, gen))
-                    {} 
-                    buffer(buffer const & rhs)
-                        : std::vector<R>(rhs)
-                        , cur(this->begin() + (rhs.cur - rhs.begin()))
-                        , fill_helper(rhs.fill_helper)
-                        , clone(rhs.clone)
-                    {
-                        if (rhs.engine)
-                            clone(*this, rhs);
-                    }
-                    inline void fill() {
-                        fill_helper(this->begin(), this->end());
-                        cur = this->begin();
-                    }
-                private:
-                    template<typename Generator> static void type_keeper(buffer & lhs, buffer const & rhs) {
-                        lhs.engine = make_shared<Generator>(*reinterpret_cast<Generator *>(rhs.engine.get()));
-                        lhs.fill_helper = lambda::bind(std::generate<typename buffer::iterator, Generator &>, lambda::_1, lambda::_2, ref(*reinterpret_cast<Generator *>(lhs.engine.get())));
-                    }
-                    shared_ptr<void> engine;
-                    typename std::vector<R>::const_iterator cur;
-                    function<void(typename std::vector<R>::iterator, typename std::vector<R>::iterator)> fill_helper;
-                    function<void(buffer &, buffer const &)> clone;
-            };
-
-            shared_ptr<buffer> buf;
-            typename buffer::const_iterator & cur;
-            typename buffer::const_iterator end;
-        };
-}
diff --git a/triqs/mc_tools/random_generator.cpp b/triqs/mc_tools/random_generator.cpp
index 214235d4..39b8cff7 100644
--- a/triqs/mc_tools/random_generator.cpp
+++ b/triqs/mc_tools/random_generator.cpp
@@ -1,9 +1,8 @@
-
 /*******************************************************************************
  *
  * TRIQS: a Toolbox for Research in Interacting Quantum Systems
  *
- * Copyright (C) 2011 by M. Ferrero, O. Parcollet
+ * Copyright (C) 2011-2014 by M. Ferrero, O. Parcollet
  *
  * TRIQS is free software: you can redistribute it and/or modify it under the
  * terms of the GNU General Public License as published by the Free Software
@@ -19,7 +18,6 @@
  * TRIQS. If not, see <http://www.gnu.org/licenses/>.
  *
  ******************************************************************************/
-
 #include "random_generator.hpp"
 #include "./MersenneRNG.hpp"
 #include <boost/random.hpp>
@@ -32,50 +30,52 @@
 #include <sstream>
 #include <boost/preprocessor/seq.hpp>
 #include <boost/preprocessor/control/if.hpp>
+
+// List of All available Boost random number generator
+#define RNG_LIST                                                                                                                 \
+ (mt19937)(mt11213b)(lagged_fibonacci607)(lagged_fibonacci1279)(lagged_fibonacci2281)(lagged_fibonacci3217)(                     \
+     lagged_fibonacci4423)(lagged_fibonacci9689)(lagged_fibonacci19937)(lagged_fibonacci23209)(lagged_fibonacci44497)(ranlux3)
+
+namespace triqs {
+namespace mc_tools {
+
+ random_generator::random_generator(std::string const& RandomGeneratorName, uint32_t seed_) {
+  _name = RandomGeneratorName;
+
+  if (RandomGeneratorName == "") {
+   gen = utility::buffered_function<double>(mc_tools::RandomGenerators::RandMT(seed_));
+   return;
+  }
+
+  boost::uniform_real<> dis;
+
 #define AS_STRING(X) AS_STRING2(X)
 #define AS_STRING2(X) #X
 
-// List of All available Boost random number generator
-#define RNG_LIST (mt19937)(mt11213b)\
-(lagged_fibonacci607) (lagged_fibonacci1279) (lagged_fibonacci2281) (lagged_fibonacci3217) (lagged_fibonacci4423)\
-(lagged_fibonacci9689) (lagged_fibonacci19937) (lagged_fibonacci23209) (lagged_fibonacci44497) (ranlux3)
+// now boost random number generators
+#define DRNG(r, data, XX)                                                                                                        \
+ if (RandomGeneratorName == AS_STRING(XX)) {                                                                                     \
+  gen = utility::buffered_function<double>(boost::variate_generator<boost::XX, boost::uniform_real<>>(boost::XX(seed_), dis));   \
+  return;                                                                                                                        \
+ }
 
+  BOOST_PP_SEQ_FOR_EACH(DRNG, ~, RNG_LIST)
 
-namespace triqs { 
- namespace mc_tools { 
-
- typedef boost::generator <double> gen_type;
-
- inline gen_type * choose_gen(std::string const & RandomGeneratorName, std::size_t seed_, boost::shared_ptr<void> &ptr) { 
-
-  if (RandomGeneratorName=="") return new gen_type( mc_tools::RandomGenerators::RandMT (seed_));
-
-  // now boost random number generators
-#define DRNG(r,data,XX) if (RandomGeneratorName==AS_STRING(XX)) { \
- boost::shared_ptr<boost::XX> localptr = boost::make_shared<boost::XX>(seed_);\
- ptr = localptr; boost::uniform_real<> dis;\
- return new gen_type( boost::variate_generator<boost::XX&, boost::uniform_real<> >(*localptr,dis));}
-
-  BOOST_PP_SEQ_FOR_EACH(DRNG,~,RNG_LIST)
-
-   TRIQS_RUNTIME_ERROR<<"The random generator "<<RandomGeneratorName<<" is not recognized";
+  TRIQS_RUNTIME_ERROR << "The random generator " << RandomGeneratorName << " is not recognized";
  }
 
  //---------------------------------------------
 
- random_generator::random_generator(std::string const & RandomGeneratorName, std::size_t seed_ ) : 
-  rng_ptr(), gen (choose_gen(RandomGeneratorName,seed_,rng_ptr)), name(RandomGeneratorName),seed(seed_) {}
+ std::string random_generator_names(std::string const &sep) {
+#define PR(r, sep, p, XX) BOOST_PP_IF(p, +sep +, ) std::string(AS_STRING(XX))
+  return BOOST_PP_SEQ_FOR_EACH_I(PR, sep, RNG_LIST);
+ }
 
- //---------------------------------------------
-
- random_generator::random_generator( random_generator const & p) :
-  rng_ptr(), gen (choose_gen(p.name,p.seed,rng_ptr)), name (p.name),seed(p.seed) {}
-
- //---------------------------------------------
-
- std::string random_generator::random_generator_names(std::string const & sep) { 
-#define PR(r,sep,p,XX) BOOST_PP_IF(p,+ sep +,) std::string(AS_STRING(XX))   
-  return BOOST_PP_SEQ_FOR_EACH_I (PR,sep,RNG_LIST);  
+ std::vector<std::string> random_generator_names_list() {
+  std::vector<std::string> res;
+#define PR2(r, sep, p, XX) res.push_back(AS_STRING(XX));
+  BOOST_PP_SEQ_FOR_EACH_I(PR2, sep, RNG_LIST);
+  return res;
  }
 }
 }
diff --git a/triqs/mc_tools/random_generator.hpp b/triqs/mc_tools/random_generator.hpp
index f3c75557..14ce5c6a 100644
--- a/triqs/mc_tools/random_generator.hpp
+++ b/triqs/mc_tools/random_generator.hpp
@@ -2,7 +2,7 @@
  *
  * TRIQS: a Toolbox for Research in Interacting Quantum Systems
  *
- * Copyright (C) 2011 by M. Ferrero, O. Parcollet
+ * Copyright (C) 2011-2014 by M. Ferrero, O. Parcollet
  *
  * TRIQS is free software: you can redistribute it and/or modify it under the
  * terms of the GNU General Public License as published by the Free Software
@@ -18,62 +18,70 @@
  * TRIQS. If not, see <http://www.gnu.org/licenses/>.
  *
  ******************************************************************************/
-
-#ifndef POLYMORPH_RANDOM_GENERATOR_H
-#define POLYMORPH_RANDOM_GENERATOR_H
+#pragma once
 #include <triqs/utility/first_include.hpp>
-#include <boost/scoped_ptr.hpp>
 #include "../utility/exceptions.hpp"
-#include "./generator.hpp"
+#include "../utility/buffered_function.hpp"
 #include "math.h"
 #include <string>
+#include <assert.h>
+#include <type_traits>
 
-namespace triqs { 
-namespace mc_tools { 
-
- /**
-  *  This is a random generator that take the name of the random generator at construct
-  *  and serve random numbers, buffered with a version boost::generator ,
-  *  to hide the cost of dynamical polymorphism.
-  */
- class random_generator {
-  boost::shared_ptr<void> rng_ptr;
-  boost::scoped_ptr< boost::generator <double> > gen;
-  std::string name;
-  void operator = ( random_generator const & p); //forbid
-  std::size_t seed;
-  public: 
-
-  /// Takes the boost name of the generator e.g. mt19937,...
-  random_generator(std::string const & RandomGeneratorName, std::size_t seed_ );
-
-  ///
-  random_generator( random_generator const & p);
+namespace triqs {
+namespace mc_tools {
 
   /// Return a list of the names of available generators, with separator sep
-  static std::string random_generator_names(std::string const & sep=" ");
+  std::string random_generator_names(std::string const & sep=" ");
+  std::vector<std::string> random_generator_names_list();
+
+ /**
+  * Random generator, adapting the boost random generator.
+  *
+  * The name of the generator is given at construction, and its type is erased in this class.
+  * For performance, the call to the generator is bufferized, with chunks of 1000 numbers.
+  */
+ class random_generator {
+  utility::buffered_function<double> gen;
+  std::string _name;
+
+  public:
+  /** Constructor
+   *  @param RandomGeneratorName : Name of a boost generator e.g. mt19937, or "" (another Mersenne Twister).
+   *  @param seed : The seed of the random generator
+   */
+  random_generator(std::string const& RandomGeneratorName, uint32_t seed_);
+
+  random_generator() : random_generator("mt19937", 198) {}
+
+  ///
+  random_generator(random_generator const& p);
+
+  random_generator(random_generator&&) = default;
+
+  //
+  random_generator & operator=(random_generator&&) = default;
+
+  /// Name of the random generator
+  std::string name() const { return _name; }
 
   /// Returns a integer in [0,i-1] with flat distribution
-#define INTEGER_OVERLOAD(T) T operator()(T i) { return (i==1 ? 0 : T(floor(i*((*gen)()))));}
-  INTEGER_OVERLOAD(int)
-  INTEGER_OVERLOAD(size_t)
-#undef INTEGER_OVERLOAD
+  template <typename T> typename std::enable_if<std::is_integral<T>::value, T>::type operator()(T i) {
+   return (i == 1 ? 0 : T(floor(i * (gen()))));
+  }
 
   /// Returns a double in [0,1[ with flat distribution
-  double preview() { return gen->preview();} 
+  double preview() { return gen.preview();} 
 
-  /// Returns a double in [0,1[ with flat distribution
-  double operator()() { return ((*gen)());} 
+  double operator()() { return gen(); }
 
   /// Returns a double in [0,x[ with flat distribution
-  double operator()(double x) { return x*((*gen)());} 
+  double operator()(double x) { return x * (gen()); }
 
   /// Returns a double in [a,b[ with flat distribution
-  double operator()(double a, double b) { assert (b>a); return a + (b-a)*((*gen)());} 
-
+  double operator()(double a, double b) {
+   assert(b > a);
+   return a + (b - a) * (gen());
+  }
  };
-
 }
 }
-
-#endif
diff --git a/triqs/utility/buffered_function.hpp b/triqs/utility/buffered_function.hpp
new file mode 100644
index 00000000..8f9e4f2e
--- /dev/null
+++ b/triqs/utility/buffered_function.hpp
@@ -0,0 +1,74 @@
+/*******************************************************************************
+ *
+ * TRIQS: a Toolbox for Research in Interacting Quantum Systems
+ *
+ * Copyright (C) 2014 by O. Parcollet
+ *
+ * TRIQS is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later
+ * version.
+ *
+ * TRIQS is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * TRIQS. If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+#pragma once
+#include <vector>
+#include <functional>
+
+namespace triqs {
+namespace utility {
+
+ /**
+  * A simple buffer for a generator.
+  * Given a function, it provides a buffer of this function
+  * Advantage :
+  *  - do not pay the indirection cost at each call, but once every size call.
+  *  - erase the function type
+  * It is a semi-regular type.
+  */
+ template <typename R> struct buffered_function {
+
+  /// Default constructor : no function bufferized. () will throw in this state
+  buffered_function() = default;
+
+  /** Constructor
+   *
+   * @tparam Function : type of the function to bufferize
+   * @param f : function to bufferize
+   * @param size : size of the buffer [optional]
+   */
+  template <typename Function> buffered_function(Function f, size_t size = 1000) : buffer(size) {
+   refill = [f](buffered_function *bf) mutable { // without the mutable, the () of the lambda object is const, hence f
+    for (auto &x : bf->buffer) x = f();
+    bf->index = 0;
+   };
+   refill(this); // first filling of the buffer
+  }
+
+  /// Returns the next element. Refills the buffer if necessary.
+  R operator()() {
+   if (index > buffer.size() - 1) refill(this);
+   return buffer[index++];
+  }
+
+  /// Returns the future next element, without increasing the index. Refills the buffer if necessary.
+  R preview() {
+   if (index > buffer.size() - 1) refill(this);
+   return buffer[index];
+  }
+
+  private:
+  size_t index;
+  std::vector<R> buffer;
+  std::function<void(buffered_function *)> refill; // this refills the buffer and reset index of a buffered_function.
+  // NB : can not capture this in refill because we want the object to be copyable and movable
+ };
+}
+}