[WIP] Support passing package name as pythran signature

docs/MANUAL.rst

@@ -217,6 +217,7 @@ Constructed types are either tuples, introduced by parenthesis, like ``(int,
                   | argument_type [:,...,3]+          # a ndarray, some dimension fixed
                   | argument_type:argument_type dict  # a dictionary
                   | argument_type type                # a type
+                  | package_name pkg                  # a package name
 
     basic_type = bool | byte | int | float | str | None | slice
                | uint8 | uint16 | uint32 | uint64 | uintp
@@ -306,6 +307,31 @@ parameter, but also types. It can be useful to write generic functions such as
 
    Container type, as in ``set type`` don't hold any information about their subtype.
 
+Concerning the ``pkg`` specification
+************************************
+
+When exporting a function that takes a ``pkg`` argument, as in
+
+.. code-block:: python
+
+   #pythran export compute(float[], numpy pkg)
+   def compute(a, xp):
+       return xp.cos(a)
+
+Pythran actually transforms your code so that any package passed as ``pkg``
+argument is named according to the specification (in our example, the name of
+the package has to be ``numpy``).
+
+There currently are several restrictions though:
+
+1. The same function cannot be exported with different package names (*a.k.a.* no
+   overloads based on the package name). This is valid for exported and non
+   exported functions.
+
+2. The package argument can only be used as an attribute root, or as a
+   non-keyword argument to other user function.
+
+
 When Pythran needs a little help: type annotation
 *************************************************
 

pythran/__init__.py

@@ -70,6 +70,7 @@
     'openmp',
     'optimizations',
     'passmanager',
+    'preprocessor',
     'spec',
     'syntax',
     'tables',

pythran/backend.py

@@ -1106,7 +1106,10 @@ def visit_Name(self, node):
         if node.id in self.local_names:
             return cxxid(node.id)
         elif node.id in self.global_declarations:
-            return "{0}()".format(cxxid(node.id))
+            if isinstance(self.types[node], self.types.builder.PkgRefType):
+                return f"{self.types[node].generate(None)}{{}}"
+            else:
+                return "{0}()".format(cxxid(node.id))
         else:
             return cxxid(node.id)
 

pythran/cxxtypes.py

@@ -266,6 +266,21 @@ def generate(self, ctx):
                 ty = ctx(self.of)
                 return f"std::integral_constant<{ty}, {str(self.index).lower()}>"
 
+        class PkgType(Type):
+            """
+            A type to hold package name
+            """
+            def __init__(self, name):
+                super(PkgType, self).__init__(name=name)
+
+            def generate(self, _):
+                return f'pythonic::types::pkg::{self.name}'
+
+        class PkgRefType(PkgType):
+            """
+            A type to hold reference to package name
+            """
+
         class ArgumentType(Type):
             """
             A type to hold function arguments

pythran/frontend.py

@@ -3,7 +3,8 @@
 """
 
 from pythran.openmp import GatherOMPData
-from pythran.syntax import check_syntax
+from pythran.syntax import check_syntax, PythranSyntaxError
+from pythran.tables import pythran_ward
 from pythran.transformations import ExtractDocStrings, HandleImport
 
 import gast as ast
@@ -16,7 +17,6 @@ def raw_parse(code):
 
     return ast.parse(code)
 
-
 def parse(pm, code):
 
     # front end