Type Conversion

PyD provides d_to_python and python_to_d for converting types to and from python. These functions almost always do a copy. If you want reference semantics, use PydObject.

D to Python

D Type Python Type
bool bool
Any integral type bool
BigInt long (int in python3)
float, double, real float
std.complex.Complex complex
std.datetime.Date datetime.date
std.datetime.DateTime datetime.datetime
std.datetime.SysTime datetime.datetime
std.datetime.Time datetime.time
string str
dynamic array list
static array list
std.typecons.Tuple tuple
associative array dict
delegates or function pointers callable object
a wrapped class wrapped type
a wrapped struct wrapped type
pointer to wrapped struct wrapped type
PydObject wrapped object’s type
PyObject* object’s type

Python to D

Python Type D Type
Any type PyObject*, PydObject
Wrapped struct Wrapped struct, pointer to wrapped struct
Wrapped class Wrapped class
Any callable delegate
array.array dynamic or static array
Any iterable dynamic or static array, PydInputRange
str string or char[]
tuple std.typecons.Tuple
complex std.complex.Complex
float float, double, real
int, long Any integral type
bool bool
buffer dynamic or static array (with many dimensions!)
datetime.date std.datetime.Date, std.datetime.DateTime, std.datetime.SysTime
datetime.datetime std.datetime.Date, std.datetime.DateTime, std.datetime.SysTime, std.datetime.Time
datetime.time std.datetime.Time


Numpy arrays implement the buffer protocol, which PyD can efficiently convert to D arrays.

To convert a D array to a numpy array, use pyd.extra.d_to_python_numpy_ndarray.

Extending PyD’s type conversion

PyD’s type conversion can be extended using ex_d_to_python and ex_python_to_d. Each takes a delegate or function pointer that performs the conversion.

Extensions will only be used if PyD’s regular type conversion mechanism fails. This would usually happen when an exposed function takes or returns an unwrapped class or struct.

module example;

import std.stdio;
import pyd.pyd;

struct S {
    int i;

S foo() {
    S s;
    s.i = 12;
    return s;

void bar(S s) {

extern(C) void PydMain() {
    ex_d_to_python((S s) => s.i);
    ex_python_to_d((int i) => S(i));