gopy

gopy generates (and compiles) a CPython extension module from a go package.

WARNING gopy is currently not compatible with Go>=1.6 and its improved CGo rules as documented in cmd/cgo. To be able to run a CPython module generated with Go>=1.6, one needs to export GODEBUG=cgocheck=0 to disable the CGo rules runtime checker. (see issue 83 for more informations.)

Installation

$ go get github.com/go-python/gopy

You will need Go >= 1.5.

Community

The go-python community can be reached out at go-python@googlegroups.com or via the web forum: go-python group. See the CONTRIBUTING guide for pointers on how to contribute to gopy.

Documentation

A presentation was given at dotgo-2015. A longer version of that talk is also available here. An article was also posted on the GopherAcademy Advent-2015.

Documentation is available on godoc: https://godoc.org/github.com/go-python/gopy

or directly from the command-line prompt:

$ gopy help
gopy - 

Commands:

    bind        generate and compile (C)Python language bindings for Go
    gen         generate (C)Python language bindings for Go

Use "gopy help <command>" for more information about a command.


$ gopy help gen
Usage: gopy gen <go-package-name>

gen generates (C)Python language bindings for a Go package.

ex:
 $ gopy gen [options] <go-package-name>
 $ gopy gen github.com/go-python/gopy/_examples/hi

Options:
  -lang="py2": target language for bindings
  -output="": output directory for bindings


$ gopy help bind
Usage: gopy bind <go-package-name>

bind generates and compiles (C)Python language bindings for a Go package.

ex:
 $ gopy bind [options] <go-package-name>
 $ gopy bind github.com/go-python/gopy/_examples/hi

Options:
  -lang="py2": python version to use for bindings (python2|py2|python3|py3|cffi)
  -output="": output directory for bindings

Examples

From the python shell

gopy comes with a little python module allowing to wrap and compile go packages directly from the python interactive shell:

>>> import gopy
>>> hi = gopy.load("github.com/go-python/gopy/_examples/hi")
gopy> inferring package name...
gopy> loading 'github.com/go-python/gopy/_examples/hi'...
gopy> importing 'github.com/go-python/gopy/_examples/hi'

>>> print hi
<module 'github.com/go-python/gopy/_examples/hi' from '/some/path/.../hi.so'>

>>> print hi.__doc__
package hi exposes a few Go functions to be wrapped and used from Python.

From the command line

$ gopy bind -output=out github.com/go-python/gopy/_examples/hi
$ ls out
hi.so

$ cd out
$ python2
>>> import hi
>>> dir(hi)
['Add', 'Concat', 'Hello', 'Hi', 'NewPerson', 'Person', '__doc__', '__file__', '__name__', '__package__']

>>> hi.Hello("you")
hello you from go

You can also run:

go test -v -run=TestBind
=== RUN   TestBind
processing "Add"...
processing "Concat"...
processing "Hello"...
processing "Hi"...
processing "NewPerson"...
processing "Person"...
processing "Add"...
processing "Concat"...
processing "Hello"...
processing "Hi"...
processing "NewPerson"...
processing "Person"...
github.com/go-python/gopy/_examples/hi
_/home/binet/dev/go/root/tmp/gopy-431003574
--- hi.Hi()...
hi from go
--- hi.Hello('you')...
hello you from go
--- hi.Add(1, 41)...
42
--- hi.Concat('4', '2')...
42
--- doc(hi.Person):
Person is a simple struct

--- p = hi.Person()...
<hi.Person object at 0x7fc46cc330f0>
['Age', 'Name', '__class__', '__delattr__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']
--- p.Name: None
--- p.Age: None
--- doc(p):
Person is a simple struct

--- PASS: TestBind (2.13s)
PASS
ok  	github.com/go-python/gopy	2.135s

Binding generation using Docker (for cross-platform builds)

$ cd github.com/go-python/gopy/_examples/hi
$ docker run --rm -v `pwd`:/go/src/in -v `pwd`:/out gopy/gopy app bind -output=/out in
$ file hi.so
hi.so: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, not stripped

The docker image can also be built on local machine:

$ cd $GOPATH/src/github.com/go-python/gopy
$ docker build -t go-python/gopy .
$ docker run -it --rm go-python/gopy

Limitations

• wrap go structs into python classes [DONE]
• better pythonization: turn go errors into python exceptions [DONE]
• wrap arrays and slices into types implementing tp_as_sequence [DONE]
• only python-2 supported for now [DONE]

Contribute

gopy is part of the go-python organization and licensed under BSD-3. When you want to contribute a patch or some code to gopy, please send a pull request against the gopy issue tracker AND a pull request against go-python/license adding yourself to the AUTHORS and CONTRIBUTORS files.