how to define a golang Multidimensional array in ctypes structure

[shen-xianpeng]

i want to call function ` func ArrayArgs(data [][]string) []string { return []string{"123"} }

`

[vladimirvivien]

Is this a question or are you telling me how to do it ? Please clarify.

[raghur]

I'm actually having trouble just calling with args that are string arrays:

my go code:

// +build lib

package main

import "C"
import (
    "github.com/sahilm/fuzzy"
)

func main() {}

//export FindMatches
func FindMatches(data []string, pattern string, max int) []string {
    matches := fuzzy.Find(pattern, data)
    if max == 0 {
        max = len(matches)
    }

    max = min(len(matches), max)
    arr := make([]string, max)
    // log.Debugf("number of matches: %v", len(matches))
    // log.Infof("[%v] Size=%v, qry=%v, matches=%v, max=%v", cid, len(data), pattern, len(matches), max)
    for i, m := range matches[:max] {
        arr[i] = m.Str
        // log.Debug(m.Str)
    }
    return arr

}

func min(x, y int) int {
    if x < y {
        return x
    }
    return y
}

the header file generated has this definition:

extern GoSlice FindMatches(GoSlice p0, GoString p1, GoInt p2);

I'd like to call this from python but not sure how to proceed.

[vladimirvivien]

Check out how the GoSlice type maps to a Python object in the write up https://github.com/vladimirvivien/go-cshared-examples#from-python

<snip>

# define class GoSlice to map to:
# C type struct { void *data; GoInt len; GoInt cap; }
class GoSlice(Structure):
    _fields_ = [("data", POINTER(c_void_p)), ("len", c_longlong), ("cap", c_longlong)]

</snip>

Then create the slice in python

nums = GoSlice((c_void_p * 5)(74, 4, 122, 9, 12), 5, 5) 

Also, the following shows how to map GoSlice type to python struct using CFFI library - https://github.com/vladimirvivien/go-cshared-examples#python-cffi-contributed

Hope that helped!

[PavelKa]

After reading both links (and many others ) I didn't find solution how to pass array of strings to go library from python. All examples shows how to work with array of ints only. Please, can anybody provide a piece of code to describe how to create GoSlice from array of strings in python so it can be passed to func Sort(vals []string) in go ?

[DanielHeath]

None of these examples show how to expose any non-primitive type (struct, slice etc) to calling code in another language (and it isn't straightforward).

[vladimirvivien]

The example shows how to pass a slice of integers in many of the languages.