A PyTrilinos Overview for Developers

1
A PyTrilinos Overview for Developers

• Bill Spotz
• Trilinos Users Group Meeting
• November 4, 2004

2
Outline

• Quick PyTrilinos demo
• Wrapping code for python
• SWIG (Simple Wrapper Interface Generator)
• Interface files
• Compiling wrapped code
• Python distutils module
• setup.py scripts
• Integration into Trilinos repository
• Current structure
• Alternative structure
• Unit test example
• PyTrilinos Issues

3
Quick PyTrilinos Demo
4
Wrapping Code for Python SWIG

• Simple Wrapper Interface Generator
• Source languages
• C
• C
• Target languages
• chicken
• csharp
• guile
• java
• mzscheme
• ocaml
• perl

• php
• python
• ruby
• sexp
• tcl
• xml
• Generate code using target language API that
• converts arguments
• calls function (method)
• converts return arguments

5
Wrapping Code for Python SWIG

• SWIG directives in interface file
• insert source code
• ignore ignore code
• rename rename function, class, etc.
• typemap define argument conversions
• include wrap functions, etc., in header file
• extend new methods for a class
• Command-line invocation
• swig -I../include -python -c interface.i
• Produces
• interface_wrap.cxx
• interface.py

6
Compiling Wrapped Code

• Need to compile interface_wrap.cxx and link to
  compiled source code to produce dynamic library
  or shared object compatible with python.
• Python distutils module to the rescue knows how
  python was compiled on current platform and how
  new modules need to be compiled.
• By convention, setup.py script
• import distutils
• Extension class
• setup() function
• Commands
• python setup.py build
• python setup.py install
• etc.

7
Integration into Trilinos Repository
Trilinos
config
doc
packages
testharness
epetra
epetraext
nox
PyTrilinos
Makefile.am
configure.ac
setup.py
src
Epetra.i
EpetraExt.i
NOX
Abstract.i
Epetra.i
Parameter.i
Solver.i
StatusTest.i
8
Alternative (Proposed) Structure
Trilinos
config
doc
packages
testharness
epetra
epetraext
nox
Makefile.am
configure.ac
python
src
test
setup.py
Makefile.am
Epetra.i
9
Unit Test Example
10
PyTrilinos Issues

• Dependencies
• Currently serial only . . .
• Python
• Numeric
• SWIG (1.3.19 - 1.3.21 . . . not 1.3.22)
• SWIG issues
• Could make _wrap.cxx files part of distribution
  . . .
• Currently relies on installed runtime libraries
  (which are deprecated in 1.3.22)
• Could compile runtime library locally . . .
  libtool
• Plans
• Eliminate SWIG dependency
• Make structure decision
• Add MPI
• Add more Trilinos packages