The new version supports pickling

extensions/climiter.pxd

@@ -1,12 +1,20 @@
 #cython: language_level=3
 from libcpp.vector cimport vector
+from libcpp.string cimport string
 
 cdef extern from "limiter.h" nogil:
 
+    cdef cppclass CLimiterState
+
     cdef cppclass CLimiter:
 
         CLimiter(float, float, int, float)
 
+        @staticmethod
+        CLimiter read_from_string(string data)
+
+        string write_to_string() const
+
         void limit_inplace(vector[float] &)
 
         vector[float] limit(const vector[float] &)

extensions/cylimiter.pyx

@@ -2,7 +2,7 @@
 from libcpp.memory cimport unique_ptr
 from libcpp.vector cimport vector
 
-from extensions.climiter cimport CLimiter
+from extensions.climiter cimport CLimiter, CLimiterState
 
 
 cdef class Limiter:
@@ -15,6 +15,16 @@ cdef class Limiter:
         assert isinstance(delay, int) and delay > 0, "Delay has to be an integer greater than zero."
         self._limiter.reset(new CLimiter(attack, release, delay, threshold))
 
+    def __setstate__(self, state: bytes) -> None:
+        self.__init__()
+        self._limiter.get().read_from_string(state)
+
+    def __getstate__(self) -> bytes:
+        return self.write_to_string()
+
+    def write_to_string(self) -> bytes:
+        return self._limiter.get().write_to_string()
+
     def _validate_input(self, audio):
         if hasattr(audio, "ndim"):
             assert audio.ndim == 1, "The input audio array has to be single-dimensional (only mono audio is supported)."
@@ -29,3 +39,7 @@ cdef class Limiter:
 
     def reset(self):
         return self._limiter.get().reset()
+
+
+def _create_default() -> Limiter:
+    return Limiter()

extensions/limiter.cpp

@@ -1,6 +1,8 @@
 #include <cmath>
 #include <algorithm>
 #include <iterator>
+#include <sstream>
+#include <utility>
 
 #include "limiter.h"
 
@@ -36,7 +38,7 @@ void CLimiter::limit_inplace(vector<float> &audio) {
     }
 }
 
-std::vector<float> CLimiter::limit(const vector<float> &audio) {
+vector<float> CLimiter::limit(const vector<float> &audio) {
     vector<float> out;
     copy(begin(audio), end(audio), back_inserter(out));
     limit_inplace(out);
@@ -52,3 +54,30 @@ void CLimiter::reset() {
         delay_line_[i] = 0.0f;
     }
 }
+
+void CLimiter::read_from_string(const string &data) {
+    istringstream str{data};
+    str >> attack_;
+    str >> release_;
+    str >> delay_;
+    str >> threshold_;
+    str >> delay_index_;
+    str >> envelope_;
+    str >> gain_;
+    float sample;
+    delay_line_.empty();
+    while(str >> sample) {
+        delay_line_.push_back(sample);
+    }
+}
+
+string CLimiter::write_to_string() const {
+    ostringstream str;
+    const auto s = " ";
+    str << attack_ << s << release_ << s << delay_ << s << threshold_ << s
+        << delay_index_ << s << envelope_ << s << gain_ << s;
+    for (const auto item : delay_line_) {
+        str << item << s;
+    }
+    return str.str();
+}

extensions/limiter.h

@@ -1,4 +1,5 @@
 #include <vector>
+#include <string>
 
 
 class CLimiter {
@@ -9,6 +10,9 @@ class CLimiter {
         std::vector<float> limit(const std::vector<float> &audio);
         void reset();
 
+        void read_from_string(const std::string &data);
+        std::string write_to_string() const;
+
     // Mutable state
     private:
         std::vector<float> delay_line_;
@@ -18,8 +22,8 @@ class CLimiter {
 
     // Settings
     private:
-        const float attack_;
-        const float release_;
-        const int delay_;
-        const float threshold_;
-};
+        float attack_;
+        float release_;
+        int delay_;
+        float threshold_;
+};

reinstall.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+set -eou pipefail
+
+pushd extensions; cython -3 --cplus *.pyx; popd
+pip uninstall -y cylimiter && pip install .
+pytest tests

setup.py

@@ -59,7 +59,7 @@ def no_cythonize(extensions, **_ignore):
     extensions = no_cythonize(extensions)
 
 
-__version__ = "0.1"
+__version__ = "0.2.0"
 
 
 this_directory = path.abspath(path.dirname(__file__))

tests/test_limiter.py

@@ -1,4 +1,5 @@
 import random
+import pickle
 import pytest
 from cylimiter import Limiter
 
@@ -66,3 +67,21 @@ def test_limiter_reset():
     limiter.reset()
     audio_lim_reset = limiter.limit(audio)
     assert audio_lim == audio_lim_reset
+
+def test_limiter_pickle_works():
+    limiter_default = Limiter()
+    limiter = Limiter(attack=0.555, delay=1000, threshold=0.2, release=0.01)
+    data = pickle.dumps(limiter)
+    limiter_unpickled = pickle.loads(data)
+
+    audio = get_audio()
+    audio_lim = limiter.limit(audio)
+    assert audio != audio_lim
+    audio_lim_unpickled = limiter_unpickled.limit(audio)
+    assert audio != audio_lim_unpickled
+
+    audio_lim_default = limiter_default.limit(audio)
+    assert audio_lim != audio_lim_default
+    assert audio_lim_unpickled != audio_lim_default
+
+    assert audio_lim == audio_lim_unpickled