[pypy-svn] r29984 - pypy/extradoc/talk/dls2006

[pedronis at codespeak.net]

Author: pedronis
Date: Wed Jul 12 16:22:53 2006
New Revision: 29984

Modified:
   pypy/extradoc/talk/dls2006/paper.tex
Log:
short discussion of RPython features vs Python, and an example of how RPython code is quite like idiomatic 
Python.



Modified: pypy/extradoc/talk/dls2006/paper.tex
==============================================================================
--- pypy/extradoc/talk/dls2006/paper.tex	(original)
+++ pypy/extradoc/talk/dls2006/paper.tex	Wed Jul 12 16:22:53 2006
@@ -120,9 +120,44 @@
 ``restricted Python'' or RPython.  This sublanguage is not restricted
 syntactically, but only in the way it manipulates objects of different
 types.  The restrictions are a compromise between the expressivity and
-the need to statically infer enough type information to generate efficient code.
-The purpose of the translation tool-suite is to compile such
-RPython programs to a variety of different platforms.
+the need to statically infer enough type information to generate
+efficient code.  RPython still supports inheritance but limited to
+single inheritance with some mix-in support, dynamic dispatch, to some
+extent keywords arguments and varargs, first-class function and class
+values, limited use of bound methods, runtime 'isinstance' and type
+queries, but no runtime reflection, further bindings in class and
+global namespaces are assumed constant. RPython code can be run on a
+Python interpreter without severe semantics mismatches, figure
+\ref{fig_create_frame} shows some RPython code from the
+\textit{Standard Interpreter}, it is still quite idiomatic Python code
+using the built-in dictionary type and first-class class values
+instantiation.
+
+\begin{figure}
+\begin{verbatim}
+  def get_frame_class(self):
+    # select the appropriate kind of frame
+    if not frame_classes:
+      setup_frame_classes()   # lazily
+    choose = 0
+    if self.co_cellvars or self.co_freevars:
+      choose |= NESTED
+    if self.co_flags & CO_GENERATOR:
+      choose |= GENERATOR
+    Frame = frame_classes[choose]
+    return Frame
+
+  def create_frame(self, space, 
+        w_globals, closure=None):
+    return self.get_frame_class()(space, self, 
+              w_globals, closure)
+\end{verbatim}
+\caption{methods from Python bytecode class to instantiate frames.}
+\label{fig_create_frame}
+\end{figure}
+
+The purpose of the translation tool-suite is to compile such RPython
+programs to a variety of different platforms.
 
 Our current efforts, and the present paper, focus on this tool-suite.
 We will not describe the Standard Interpreter component of PyPy in the