From e93adc0b846e92817bad908d09cae41daf1a6942 Mon Sep 17 00:00:00 2001
From: Hartmut Hafermann <soliton77@gmail.com>
Date: Mon, 13 Oct 2014 17:40:32 +0200
Subject: [PATCH] [gfs] add << operator for gfs

kept <<= for backward compatibility
TODO: clean doc and examples, possibly add deprecation warning
---
 pytriqs/gf/local/_gf_common.py |  3 +++
 pytriqs/gf/local/block_gf.py   | 11 +++++++++++
 pytriqs/gf/local/gf_desc.py    |  3 +++
 3 files changed, 17 insertions(+)

diff --git a/pytriqs/gf/local/_gf_common.py b/pytriqs/gf/local/_gf_common.py
index 497af4b1..6ffd74a2 100644
--- a/pytriqs/gf/local/_gf_common.py
+++ b/pytriqs/gf/local/_gf_common.py
@@ -73,6 +73,9 @@ def mul_precall (self, y):
 
 def div_precall (self, y):
     if descriptor_base.is_lazy(y): return lazy_expressions.make_lazy(self) / y
+
+def _lshift_(self, A):
+    return _ilshift_(self, A)
  
 def _ilshift_(self, A):
     """ A can be two things:
diff --git a/pytriqs/gf/local/block_gf.py b/pytriqs/gf/local/block_gf.py
index da6e88c3..50964ebb 100644
--- a/pytriqs/gf/local/block_gf.py
+++ b/pytriqs/gf/local/block_gf.py
@@ -232,6 +232,17 @@ class BlockGf(object):
     def __le__(self, other) : 
         raise RuntimeError, " Operator <= not defined "
 
+    def __lshift__(self, A): 
+        """ A can be 2 things :
+          * G << any_init will init all the BlockGf with the initializer
+          * G << g2 where g2 is a BlockGf will copy g2 into self
+          """
+        if isinstance(A, self.__class__):
+           for (i,g) in self : g.copy_from(A[i])
+        else: 
+           for i,g in self:  g << A
+        return self
+
     def __ilshift__(self, A): 
         """ A can be 2 things :
           * G <<= any_init will init all the BlockGf with the initializer
diff --git a/pytriqs/gf/local/gf_desc.py b/pytriqs/gf/local/gf_desc.py
index 0365f42a..570c6b60 100644
--- a/pytriqs/gf/local/gf_desc.py
+++ b/pytriqs/gf/local/gf_desc.py
@@ -313,6 +313,9 @@ def make_gf( py_type, c_tag, is_complex_data = True, is_im = False, has_tail = T
     g.number_protocol['multiply'].python_precall = "pytriqs.gf.local._gf_common.mul_precall"
     g.number_protocol['divide'].python_precall   = "pytriqs.gf.local._gf_common.div_precall"
 
+    g.number_protocol['lshift'] = pyfunction(name ="__lshift__", python_precall = "pytriqs.gf.local._gf_common._lshift_", arity = 2)
+
+    # For backward compatibility
     g.number_protocol['inplace_lshift'] = pyfunction(name ="__inplace_lshift__", python_precall = "pytriqs.gf.local._gf_common._ilshift_", arity = 2)
 
     g.add_method(name = "invert", calling_pattern = "invert_in_place(self_c)" , signature = "void()", doc = "Invert (in place)")