gpython/examples/embedding/mylib.module.go at main · go-python/gpython · GitHub

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// Use of this source code is governed by a BSD-style

// license that can be found in the LICENSE file.

package main

import (

"fmt"

"runtime"

"github.com/go-python/gpython/py"

)

// These gpython py.Object type delcarations are the bridge between gpython and embedded Go types.

var (

PyVacationStopType = py.NewType("Stop", "")

PyVacationType = py.NewType("Vacation", "")

)

// init is where you register your embedded module and attach methods to your embedded class types.

func init() {

// For each of your embedded python types, attach instance methods.

// When an instance method is invoked, the "self" py.Object is the instance.

PyVacationStopType.Dict["Set"] = py.MustNewMethod("Set", VacationStop_Set, 0, "")

PyVacationStopType.Dict["Get"] = py.MustNewMethod("Get", VacationStop_Get, 0, "")

PyVacationType.Dict["add_stops"] = py.MustNewMethod("Vacation.add_stops", Vacation_add_stops, 0, "")

PyVacationType.Dict["num_stops"] = py.MustNewMethod("Vacation.num_stops", Vacation_num_stops, 0, "")

PyVacationType.Dict["get_stop"] = py.MustNewMethod("Vacation.get_stop", Vacation_get_stop, 0, "")

// Bind methods attached at the module (global) level.

// When these are invoked, the first py.Object param (typically "self") is the bound *Module instance.

methods := []*py.Method{

py.MustNewMethod("VacationStop_new", VacationStop_new, 0, ""),

py.MustNewMethod("Vacation_new", Vacation_new, 0, ""),

}

// Register a ModuleImpl instance used by the gpython runtime to instantiate new py.Module when first imported.

py.RegisterModule(&py.ModuleImpl{

Info: py.ModuleInfo{

Name: "mylib_go",

Doc: "Example embedded python module",

Methods: methods,

Globals: py.StringDict{

"PY_VERSION": py.String("Python 3.4 (github.com/go-python/gpython)"),

"GO_VERSION": py.String(fmt.Sprintf("%s on %s %s", runtime.Version(), runtime.GOOS, runtime.GOARCH)),

"MYLIB_VERS": py.String("Vacation 1.0 by Fletch F. Fletcher"),

OnContextClosed: func(instance *py.Module) {

py.Println(instance, "<<< host py.Context of py.Module instance closing >>>\n+++")

})

}

// VacationStop is an example Go struct to embed.

type VacationStop struct {

Desc py.String

NumNights py.Int

}

// Type comprises the py.Object interface, allowing a Go struct to be cast as a py.Object.

// Instance methods of an type are then attached to this type object

func (stop *VacationStop) Type() *py.Type {

return PyVacationStopType

}

func (stop *VacationStop) M__str__() (py.Object, error) {

line := fmt.Sprintf(" %-16v | %2v nights", stop.Desc, stop.NumNights)

return py.String(line), nil

}

func (stop *VacationStop) M__repr__() (py.Object, error) {

return stop.M__str__()

}

func VacationStop_new(module py.Object, args py.Tuple) (py.Object, error) {

stop := &VacationStop{}

VacationStop_Set(stop, args)

return stop, nil

}

// VacationStop_Set is an embedded instance method of VacationStop

func VacationStop_Set(self py.Object, args py.Tuple) (py.Object, error) {

stop := self.(*VacationStop)

// Check out other convenience functions in py/util.go

// Also available is py.ParseTuple(args, "si", ...)

err := py.LoadTuple(args, []interface{}{&stop.Desc, &stop.NumNights})

if err != nil {

return nil, err

}

/* Alternative util func is ParseTuple():

var desc, nights py.Object

err := py.ParseTuple(args, "si", &desc, &nights)

if err != nil {

return nil, err

}

stop.Desc = desc.(py.String)

stop.NumNights = desc.(py.Int)

return py.None, nil

}

// VacationStop_Get is an embedded instance method of VacationStop

func VacationStop_Get(self py.Object, args py.Tuple) (py.Object, error) {

stop := self.(*VacationStop)

return py.Tuple{

stop.Desc,

stop.NumNights,

}, nil

}

type Vacation struct {

Stops []*VacationStop

MadeBy string

}

func (v *Vacation) Type() *py.Type {

return PyVacationType

}

func Vacation_new(module py.Object, args py.Tuple) (py.Object, error) {

v := &Vacation{}

// For Module-bound methods, we have easy access to the parent Module

py.LoadAttr(module, "MYLIB_VERS", &v.MadeBy)

ret := py.Tuple{

py.String(v.MadeBy),

}

return ret, nil

}

func Vacation_num_stops(self py.Object, args py.Tuple) (py.Object, error) {

v := self.(*Vacation)

return py.Int(len(v.Stops)), nil

}

func Vacation_get_stop(self py.Object, args py.Tuple) (py.Object, error) {

v := self.(*Vacation)

// Check out other convenience functions in py/util.go

// If you would like to be a contributor for gpython, improving these or adding more is a great place to start!

stopNum, err := py.GetInt(args[0])

if err != nil {

return nil, err

}

if stopNum < 1 || int(stopNum) > len(v.Stops) {

return nil, py.ExceptionNewf(py.IndexError, "invalid stop index")

}

return py.Object(v.Stops[stopNum-1]), nil

}

func Vacation_add_stops(self py.Object, args py.Tuple) (py.Object, error) {

v := self.(*Vacation)

srcStops, ok := args[0].(py.Tuple)

if !ok {

return nil, py.ExceptionNewf(py.TypeError, "expected Tuple, got %T", args[0])

}

for _, arg := range srcStops {

stop, ok := arg.(*VacationStop)

if !ok {

return nil, py.ExceptionNewf(py.TypeError, "expected Stop, got %T", arg)

}

v.Stops = append(v.Stops, stop)

}

return py.None, nil

}

gpython/examples/embedding/mylib.module.go at main · go-python/gpython · GitHub

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