Make Python extensions compatible with venv

Cantera · Sep 11, 2022 · 5e15f57 · 5e15f57
1 parent 7ace1bc
commit 5e15f57
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Showing 2 changed files with 33 additions and 8 deletions.
diff --git a/include/cantera/extensions/PythonExtensionManager.h b/include/cantera/extensions/PythonExtensionManager.h
@@ -31,6 +31,9 @@ class PythonExtensionManager : public ExtensionManager
     //! Function called from Cython to register an ExtensibleRate implementation
     static void registerPythonRateBuilder(const std::string& moduleName,
         const std::string& className, const std::string& rateName);
+
+private:
+    static bool s_imported;
 };
 
 }

diff --git a/src/extensions/PythonExtensionManager.cpp b/src/extensions/PythonExtensionManager.cpp
@@ -10,6 +10,7 @@
 #include "pythonExtensions.h" // generated by Cython
 
 #include <boost/algorithm/string.hpp>
+#include <codecvt>
 
 #ifdef _WIN32
 #include <windows.h>
@@ -67,20 +68,40 @@ std::string getPythonExceptionInfo()
 namespace Cantera
 {
 
+bool PythonExtensionManager::s_imported = false;
+
 PythonExtensionManager::PythonExtensionManager()
 {
     if (!Py_IsInitialized()) {
-        #if defined(CT_PYTHONHOME) && defined(_WIN32)
-            const char* old_pythonhome = getenv("PYTHONHOME");
-            if (old_pythonhome == nullptr || old_pythonhome[0] == '\0') {
-                std::string pythonhome = "PYTHONHOME=";
-                pythonhome += CT_PYTHONHOME;
-                _putenv(pythonhome.c_str());
-            }
-        #endif
+        // Update the path to include the virtual environment, if one is active
+        const char* venv_path = getenv("VIRTUAL_ENV");
+        if (venv_path != nullptr) {
+            #ifdef _WIN32
+                string suffix = "\\Scripts\\python.exe";
+            #else
+                string suffix = "/bin/python";
+            #endif
+            string path(venv_path);
+            path += suffix;
+            wstring wpath = wstring_convert<codecvt_utf8<wchar_t>>().from_bytes(path);
+            Py_SetProgramName(wpath.c_str());
+        } else {
+            #if defined(CT_PYTHONHOME) && defined(_WIN32)
+                const char* old_pythonhome = getenv("PYTHONHOME");
+                if (old_pythonhome == nullptr || old_pythonhome[0] == '\0') {
+                    string pythonhome = "PYTHONHOME=";
+                    pythonhome += CT_PYTHONHOME;
+                    _putenv(pythonhome.c_str());
+                }
+            #endif
+        }
         Py_Initialize();
     }
 
+    if (s_imported) {
+        return;
+    }
+
     // PEP 489 Multi-phase initialization
 
     // The 'pythonExtensions' Cython module defines some functions that are used
@@ -130,6 +151,7 @@ PythonExtensionManager::PythonExtensionManager()
     }
     Py_DECREF(spec);
     Py_DECREF(pyModule);
+    s_imported = true;
 }
 
 void PythonExtensionManager::registerRateBuilders(const string& extensionName)