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ENH: Add to and from object support for std::pair. #72

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ENH: Add to and from object support for std::pair. #72

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10 changes: 10 additions & 0 deletions include/libpy/from_object.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#include <Python.h>
Expand Down Expand Up @@ -356,6 +357,15 @@ struct from_object<std::tuple<Ts...>> {
}
};

template<typename T, typename U>
struct from_object<std::pair<T, U>> {
public:
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we can drop the publics from these structs.

static std::pair<T, U> f(PyObject* tup) {
std::tuple<T, U> tmp = from_object<std::tuple<T, U>>(tup);
return std::make_pair(std::get<0>(tmp), std::get<1>(tmp));
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We should probably move the values from the old tuple in the resulting pair. For things like vector and string this will trigger a copy.

}
};

template<typename T>
struct from_object<std::optional<T>> {
static std::optional<T> f(PyObject* maybe_value) {
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11 changes: 11 additions & 0 deletions include/libpy/to_object.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

#include <Python.h>
Expand Down Expand Up @@ -296,6 +297,16 @@ struct to_object<std::tuple<Ts...>> {
}
};

template<typename T, typename U>
struct to_object<std::pair<T, U>> {
public:
static PyObject* f(const std::pair<T, U>& p) {
// Delegate to std::tuple dispatch.
return std::move(py::to_object(std::make_tuple(std::get<0>(p), std::get<1>(p))))
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This will already be an rvalue, so we don't need to move

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This is triggering an extra copy. Should we just pull the tuple to_object into a helper base class that accepts tuple-likes and subclass from that? This is how we handle mappings and sequences.

.escape();
}
};

template<typename T>
struct to_object<std::optional<T>> {
static PyObject* f(const std::optional<T>& maybe_value) {
Expand Down