This file shows some use case of Pythran on the command line.
Firstly lets clear the working space:
$> rm -f cli_*
One of the most classic use case in Pythran is to generate a native .so module:
$> printf '#pythran export foo()\n#pythran export msg\nmsg = \"hello world\"\ndef foo(): print(msg)' > cli_foo.py
$> pythran cli_foo.py -o cli_foo.so
$> ls cli_foo.so
cli_foo.so
The generated native .so
module can then be used with the Python interpreter:
$> python -c 'import cli_foo ; cli_foo.foo()'
hello world
$> python -c 'import cli_foo ; print(cli_foo.msg)'
hello world
Pythran version can be dumped through --version
:
$> pythran --version 2>&1
0.16.1
The module-level __pythran__
variable indicates that the module loaded has been pythranized:
$> python -c 'import cli_foo ; print(hasattr(cli_foo, \"__pythran__\"))'
True
You can choose your optimization level by using -O
flag:
$> rm cli_foo.so
$> pythran cli_foo.py -O2 -o cli_foo.so
$> ls cli_foo.so
cli_foo.so
You can use -p
option to apply a Pythran optimization. For example, the python
code can propagate constants using the Pythran ConstantFolding optimization:
$> pythran -e cli_foo.py -p pythran.optimizations.ConstantFolding
If you want to specify the path of generated file:
$> pythran cli_foo.py -o /tmp/cli_foo.so -DNDEBUG
$> ls /tmp/cli_foo.so
/tmp/cli_foo.so
Out of curiosity, you can check the generated output:
$> pythran -E cli_foo.py
That’s some heavily templated code ;-) Pythran can then compile it for you to a Python module:
$> pythran cli_foo.cpp -o cli_foo.so
Pythran can also generate raw C++ code, using the -e
switch:
$> printf 'msg = \"hello world\"\ndef bar(): print(msg)' > cli_bar.py
$> pythran -e cli_bar.py -w -o cli_bar.hpp
$> printf '#include \"cli_bar.hpp\"\nusing namespace __pythran_cli_bar ; int main() { bar()(); return 0 ; }' > cli_bar.cpp
$> `pythran-config --compiler --cflags` -std=c++11 cli_bar.cpp -o cli_bar
$> ./cli_bar
hello world
To know more options about Pythran, you can check:
$> pythran --help
usage: pythran [-h] [-o OUTPUT_FILE] [-P] [-E] [-e] [-v] [-w] [-V] [-p pass]
[-I include_dir] [-L ldflags] [-D macro_definition]
[-U macro_definition] [--config config] [-ftime-report]
[--trace-allocations]
input_file
pythran: a python to C++ compiler
positional arguments:
input_file the pythran module to compile, either a .py or a .cpp
file
optional arguments:
-h, --help show this help message and exit
-o OUTPUT_FILE path to generated file. Honors %{ext}.
-P only run the high-level optimizer, do not compile
-E only run the translator, do not compile
-e similar to -E, but does not generate python glue
-v be more verbose
-w be less verbose
-V, --version show program's version number and exit
-p pass any pythran optimization to apply before code
generation
-I include_dir any include dir relevant to the underlying C++ compiler
-L ldflags any search dir relevant to the linker
-D macro_definition any macro definition relevant to the underlying C++
compiler
-U macro_definition any macro undef relevant to the underlying C++ compiler
--config config config additional params
-ftime-report report time spent in each optimization/transformation
--trace-allocations instrument execution to trace memory allocations
It's a megablast!