zeroshade commented on pull request #11037:
URL: https://github.com/apache/arrow/pull/11037#issuecomment-911915670
@pitrou I'm rather happy with myself at the moment since I've managed to
actually pull your suggestion off, though i'm not sure the best way to actually
incorporate such a test into the current build system. For posterity, here's
some snippets showing what I did:
Created a go file with the following:
```go
package main
import (
"fmt"
"unsafe"
"github.com/apache/arrow/go/arrow/cdata"
)
// #include <stdint.h>
import "C"
//export importSchema
func importSchema(ptr C.uintptr_t) {
sc := (*cdata.CArrowSchema)(unsafe.Pointer(uintptr(ptr)))
fmt.Println(cdata.ImportCArrowSchema(sc))
}
func main() {}
```
In order to build a c-shared library it apparently needs to be a main
package. Anyway, the above file will export a function "importSchema" which
takes a uintptr_t which is a pointer to an `struct ArrowSchema`. Running the
command `go build -buildmode=c-shared -o gotest.dll .` if on windows or using
`gotest.so` for linux. Then in python I did the following:
```python
>>> import pyarrow as pa
>>> from pyarrow.cffi import ffi
>>> c_schema = ffi.new("struct ArrowSchema*")
>>> ptr_schema = int(ffi.cast("uintptr_t", c_schema))
>>> pa.schema([('ints', pa.list_(pa.int32()))], metadata={b'key1':
b'value1'})._export_to_c(ptr_schema)
>>> from ctypes import *
>>> gotest = cdll.LoadLibrary('gotest.dll') # or gotest.so
>>> gotest.importSchema(c_ulonglong(ptr_schema))
schema:
fields: 1
- ints: type=list<item: int32>, nullable
metadata: ["key1": "value1"]
0
```
So all in all, really cool. But I don't know where in the tests would make
sense for how I should incorporate such a test where I build the go dynamic lib
and then run the a python script with pyarrow to call the function. Any ideas?
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