[gfs] add << operator for gfs

kept <<= for backward compatibility
TODO: clean doc and examples, possibly add deprecation warning

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:

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

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)")