Changed non system clocks to be time deltas

Allowed durations and non system clocks to be set from floats.

docs/advanced.rst

@@ -764,19 +764,25 @@ When including the additional header file :file:`pybind11/chrono.h` conversions
 to corresponding python datetime objects are automatically enabled.
 The following rules describe how the conversions are applied.
 
-Objects of type ``std::chrono::system_clock::time_point`` are converted into datetime.datetime objects.
+When passed to python objects of type ``std::chrono::system_clock::time_point`` are converted into datetime.datetime objects.
 These objects are those that specifically come from the system_clock as this is the only clock that measures wall time.
 
-Objects of type ``std::chrono::[other_clock]::time_point`` are converted into datetime.time objects.
+When passed to python of type ``std::chrono::[other_clock]::time_point`` are converted into datetime.timedelta objects.
 These objects are those that come from all clocks that are not the system_clock (e.g. steady_clock).
 Clocks other than the system_clock are not measured from wall date/time and instead have any start time
 (often when the computer was turned on).
-Therefore as these clocks can only measure time from an arbitrary start point they are represented as time without date.
+Therefore as these clocks can only measure time from an arbitrary start point they are represented as timedelta from this start point.
 
-Objects of type ``std::chrono::duration`` are converted into datetime.timedelta objects.
+When passed to python of type ``std::chrono::duration`` are converted into datetime.timedelta objects.
+
+When python objects are passed to c++ for the case of non system clocks and durations instances of both datetime.timedelta
+and float are accepted. The float arguments are interpreted as a number of seconds since the epoch.
 
 .. note::
 
+    Other clocks may be the same as system_clock. For example on many platforms std::high_resolution_clock is the same as system_clock.
+    Because of this if you are converting a timepoint from one of these clocks they may appear to python as a datetime.datetime object.
+
     Pythons datetime implementation is limited to microsecond precision.
     The extra precision that c++11 clocks can have have (nanoseconds) will be lost upon conversion.
     The rounding policy from c++ to python is via ``std::chrono::duration_cast<>`` (rounding towards 0 in microseconds).

include/pybind11/chrono.h

@@ -24,9 +24,12 @@ public:
 
     bool load(handle src, bool) {
         using namespace std::chrono;
+
+        // Lazy initialise the PyDateTime import
         if(!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
         if (!src) return false;
+        // If they have passed us a datetime.delta object
         if (PyDelta_Check(src.ptr())) {
             // The accessor macros for timedelta exist in some versions of python but not others (e.g. Mac OSX default python)
             // Therefore we are just doing what the macros do explicitly
@@ -37,6 +40,13 @@ public:
                 + microseconds(delta->microseconds));
             return true;
         }
+        // If they have passed us a float we can assume it is seconds and convert
+        else if (PyFloat_Check(src.ptr())) {
+            double val = PyFloat_AsDouble(src.ptr());
+            // Multiply by the reciprocal of the ratio and round
+            value = type(std::lround(val * type::period::den / type::period::num));
+            return true;
+        }
         else return false;
     }
 
@@ -45,9 +55,9 @@ public:
         if(!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
         // Declare these special duration types so the conversions happen with the correct primitive types (int)
-        typedef duration<int, std::ratio<86400>> dd_t;
+        using dd_t = duration<int, std::ratio<86400>>;
-        typedef duration<int, std::ratio<1>> ss_t;
+        using ss_t = duration<int, std::ratio<1>>;
-        typedef duration<int, std::micro> us_t;
+        using us_t = duration<int, std::micro>;
 
         return PyDelta_FromDSU(
               duration_cast<dd_t>(src).count()
@@ -57,11 +67,14 @@ public:
     PYBIND11_TYPE_CASTER(type, _("datetime.timedelta"));
 };
 
+// This is for casting times on the system clock into datetime.datetime instances
 template <typename Duration> class type_caster<std::chrono::time_point<std::chrono::system_clock, Duration>> {
 public:
     typedef std::chrono::time_point<std::chrono::system_clock, Duration> type;
     bool load(handle src, bool) {
         using namespace std::chrono;
+
+        // Lazy initialise the PyDateTime import
         if(!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
         if (!src) return false;
@@ -83,6 +96,8 @@ public:
 
     static handle cast(const std::chrono::time_point<std::chrono::system_clock, Duration> &src, return_value_policy /* policy */, handle /* parent */) {
         using namespace std::chrono;
+
+        // Lazy initialise the PyDateTime import
         if(!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
         time_t tt = system_clock::to_time_t(src);
@@ -104,21 +119,33 @@ public:
     PYBIND11_TYPE_CASTER(type, _("datetime.datetime"));
 };
 
+// Other clocks that are not the system clock are not measured as datetime.datetime objects
+// since they are not measured on calendar time. So instead we just make them timedeltas
+// Or if they have passed us a time as a float we convert that
 template <typename Clock, typename Duration> class type_caster<std::chrono::time_point<Clock, Duration>> {
 public:
     typedef std::chrono::time_point<Clock, Duration> type;
+    typedef std::chrono::duration<std::chrono::hours::rep, std::ratio<86400>> days;
+
     bool load(handle src, bool) {
         using namespace std::chrono;
         if(!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
-        if (!src) return false;
+        // If they have passed us a datetime.delta object
-        if (PyTime_Check(src.ptr())) {
+        if (PyDelta_Check(src.ptr())) {
-            value = type(duration_cast<Duration>(
+            // The accessor macros for timedelta exist in some versions of python but not others (e.g. Mac OSX default python)
-                   hours(PyDateTime_TIME_GET_HOUR(src.ptr()))
+            // Therefore we are just doing what the macros do explicitly
-                 + minutes(PyDateTime_TIME_GET_MINUTE(src.ptr()))
+            const PyDateTime_Delta* delta = reinterpret_cast<PyDateTime_Delta*>(src.ptr());
-                 + seconds(PyDateTime_TIME_GET_SECOND(src.ptr()))
+            value = time_point<Clock, Duration>(
-                 + microseconds(PyDateTime_TIME_GET_MICROSECOND(src.ptr()))
+                  days(delta->days)
-            ));
+                + seconds(delta->seconds)
+                + microseconds(delta->microseconds));
+            return true;
+        }
+        // If they have passed us a float we can assume it is seconds and convert
+        else if (PyFloat_Check(src.ptr())) {
+            double val = PyFloat_AsDouble(src.ptr());
+            value = time_point<Clock, Duration>(Duration(std::lround((val / Clock::period::num) * Clock::period::den)));
             return true;
         }
         else return false;
@@ -126,21 +153,23 @@ public:
 
     static handle cast(const std::chrono::time_point<Clock, Duration> &src, return_value_policy /* policy */, handle /* parent */) {
         using namespace std::chrono;
+
+        // Lazy initialise the PyDateTime import
         if(!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
         // Declare these special duration types so the conversions happen with the correct primitive types (int)
-        typedef duration<int, std::ratio<3600>> hh_t;
+        using dd_t = duration<int, std::ratio<86400>>;
-        typedef duration<int, std::ratio<60>> mm_t;
+        using ss_t = duration<int, std::ratio<1>>;
-        typedef duration<int, std::ratio<1>> ss_t;
+        using us_t = duration<int, std::micro>;
-        typedef duration<int, std::micro> us_t;
 
         Duration d = src.time_since_epoch();
-        return PyTime_FromTime(duration_cast<hh_t>(d).count()
+
-                               , duration_cast<mm_t>(d % hours(1)).count()
+        return PyDelta_FromDSU(
-                               , duration_cast<ss_t>(d % minutes(1)).count()
+              duration_cast<dd_t>(d).count()
-                               , duration_cast<us_t>(d % seconds(1)).count());
+            , duration_cast<ss_t>(d % days(1)).count()
+            , duration_cast<us_t>(d % seconds(1)).count());
     }
-    PYBIND11_TYPE_CASTER(type, _("datetime.time"));
+    PYBIND11_TYPE_CASTER(type, _("datetime.timedelta"));
 };
 
 NAMESPACE_END(detail)

tests/test_chrono.cpp

@@ -43,6 +43,11 @@ std::chrono::steady_clock::time_point test_chrono6(std::chrono::steady_clock::ti
     return t;
 }
 
+// Roundtrip a duration in microseconds from a float argument
+std::chrono::microseconds test_chrono7(std::chrono::microseconds t) {
+    return t;
+}
+
 test_initializer chrono([] (py::module &m) {
     m.def("test_chrono1", &test_chrono1);
     m.def("test_chrono2", &test_chrono2);
@@ -50,4 +55,5 @@ test_initializer chrono([] (py::module &m) {
     m.def("test_chrono4", &test_chrono4);
     m.def("test_chrono5", &test_chrono5);
     m.def("test_chrono6", &test_chrono6);
+    m.def("test_chrono7", &test_chrono7);
 });

tests/test_chrono.py

@@ -82,21 +82,33 @@ def test_chrono_steady_clock():
     time1 = test_chrono5()
     time2 = test_chrono5()
 
-    assert isinstance(time1, datetime.time)
+    assert isinstance(time1, datetime.timedelta)
-    assert isinstance(time2, datetime.time)
+    assert isinstance(time2, datetime.timedelta)
 
 
 def test_chrono_steady_clock_roundtrip():
     from pybind11_tests import test_chrono6
     import datetime
 
-    time1 = datetime.time(second=10, microsecond=100)
+    time1 = datetime.timedelta(days=10, seconds=10, microseconds=100)
     time2 = test_chrono6(time1)
 
-    assert isinstance(time2, datetime.time)
+    assert isinstance(time2, datetime.timedelta)
 
     # They should be identical (no information lost on roundtrip)
-    assert time1.hour == time2.hour
+    assert time1.days == time2.days
-    assert time1.minute == time2.minute
+    assert time1.seconds == time2.seconds
-    assert time1.second == time2.second
+    assert time1.microseconds == time2.microseconds
-    assert time1.microsecond == time2.microsecond
+
+
+def test_floating_point_duration():
+    from pybind11_tests import test_chrono7
+    import datetime
+
+    # Test using 35.525123 seconds as an example floating point number in seconds
+    time = test_chrono7(35.525123)
+
+    assert isinstance(time, datetime.timedelta)
+
+    assert time.seconds == 35
+    assert time.microseconds == 525123