[pypy-commit] pypy default: Add a faq entry.

arigo noreply at buildbot.pypy.org
Fri Sep 2 08:44:12 CEST 2011

Author: Armin Rigo <arigo at tunes.org>
Changeset: r47004:8eee94a7ba6b
Date: 2011-09-02 08:39 +0200

Log:	Add a faq entry.

diff --git a/pypy/doc/faq.rst b/pypy/doc/faq.rst
--- a/pypy/doc/faq.rst
+++ b/pypy/doc/faq.rst
@@ -315,6 +315,22 @@
 .. _`Andrew Brown's tutorial`: http://morepypy.blogspot.com/2011/04/tutorial-writing-interpreter-with-pypy.html
+Can RPython modules for PyPy be translated independently?
+No, you have to rebuild the entire interpreter.  This means two things:
+* It is imperative to use test-driven development.  You have to test
+  exhaustively your module in pure Python, before even attempting to
+  translate it.  Once you translate it, you should have only a few typing
+  issues left to fix, but otherwise the result should work out of the box.
+* Second, and perhaps most important: do you have a really good reason
+  for writing the module in RPython in the first place?  Nowadays you
+  should really look at alternatives, like writing it in pure Python,
+  using ctypes if it needs to call C code.
 Why does PyPy draw a Mandelbrot fractal while translating?

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