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examples: show how to create and pass a V string to a V function, and then get back a V string in Python

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Delyan Angelov 2024-06-03 19:26:17 +03:00
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14
examples/call_v_from_python/test.py
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@ -1,12 +1,26 @@
from ctypes import * from ctypes import *
import math, os import math, os
## Load the V shared library:
so_file="./test.so" so_file="./test.so"
if os.name=="nt": if os.name=="nt":
so_file="./test.dll" so_file="./test.dll"
lib = CDLL(so_file) lib = CDLL(so_file)
## Pass an integer to a V function, and receiving back an integer:
print("lib.square(10) result is", lib.square(10)) print("lib.square(10) result is", lib.square(10))
assert lib.square(10) == 100, "Cannot validate V square()." assert lib.square(10) == 100, "Cannot validate V square()."
## Pass a floating point number to a V function:
lib.sqrt_of_sum_of_squares.restype = c_double lib.sqrt_of_sum_of_squares.restype = c_double
assert lib.sqrt_of_sum_of_squares(c_double(1.1), c_double(2.2)) == math.sqrt(1.1*1.1 + 2.2*2.2), "Cannot validate V sqrt_of_sum_of_squares()." assert lib.sqrt_of_sum_of_squares(c_double(1.1), c_double(2.2)) == math.sqrt(1.1*1.1 + 2.2*2.2), "Cannot validate V sqrt_of_sum_of_squares()."
## Passing a V string to a V function, and receiving back a V string:
class VString(Structure):
_fields_ = [("str", c_char_p), ("len", c_int)]
lib.process_v_string.argtypes = [VString]
lib.process_v_string.restype = VString
assert lib.process_v_string(VString(b'World', 5)).str == b'v World v'
print('Hello', str(lib.process_v_string(VString(b'World', 5)).str, 'utf-8'))

7
examples/call_v_from_python/test.v
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@ -1,5 +1,6 @@
module test module test
// Note: compile this with `v -d no_backtrace -shared test.v`
import math import math
@[export: 'square'] @[export: 'square']
@ -11,3 +12,9 @@ fn square(i int) int {
fn sqrt_of_sum_of_squares(x f64, y f64) f64 { fn sqrt_of_sum_of_squares(x f64, y f64) f64 {
return math.sqrt(x * x + y * y) return math.sqrt(x * x + y * y)
} }
// you do not have to use the same name in the export attribute
@[export: 'process_v_string']
fn work(s string) string {
return 'v ${s} v'
}