Support `pyimport` on the Javascript side.

Makefile

@@ -23,7 +23,8 @@ all: build/pyodide.asm.html build/pyodide.js
 
 
 build/pyodide.asm.html: src/main.bc src/jsimport.bc src/jsproxy.bc src/js2python.bc \
-                        src/pyproxy.bc src/python2js.bc src/runpython.bc root
+                        src/pyimport.bc src/pyproxy.bc src/python2js.bc \
+												src/runpython.bc root
 	$(CC) -s EXPORT_NAME="'pyodide'" --bind -o $@ $(filter %.bc,$^) $(LDFLAGS) \
 		$(foreach d,$(wildcard root/*),--preload-file $d@/$(notdir $d))
 

src/jsimport.cpp

@@ -2,6 +2,11 @@
 
 #include "js2python.hpp"
 
+////////////////////////////////////////////////////////////
+// JsImport
+//
+// Makes 'from js import foo' work in Python.
+
 using emscripten::val;
 
 static PyObject *original__import__;
@@ -97,10 +102,12 @@ int JsImport_Ready() {
   if (m == NULL) {
     return 1;
   }
+
   PyObject *d = PyModule_GetDict(m);
   if (d == NULL) {
     return 1;
   }
+
   original__import__ = PyDict_GetItemString(d, "__import__");
   if (original__import__ == NULL) {
     return 1;
@@ -117,14 +124,18 @@ int JsImport_Ready() {
   }
 
   m = PyImport_AddModule("__main__");
-  if (m == NULL)
+  if (m == NULL) {
     return 1;
-  globals = PyModule_GetDict(m);
+  }
 
-  m = PyImport_AddModule("builtins");
-  PyDict_Update(globals, PyModule_GetDict(m));
+  globals = PyModule_GetDict(m);
+  if (globals == NULL) {
+    return 1;
+  }
 
-  original_globals = PyDict_Copy(globals);
+  if (PyDict_Update(globals, d)) {
+    return 1;
+  }
 
   return 0;
 }

src/jsimport.hpp

@@ -5,6 +5,5 @@
 
 int JsImport_Ready();
 extern PyObject *globals;
-extern PyObject *original_globals;
 
 #endif /* JSIMPORT_H */

src/main.cpp

@@ -7,6 +7,7 @@
 #include "jsimport.hpp"
 #include "jsproxy.hpp"
 #include "js2python.hpp"
+#include "pyimport.hpp"
 #include "pyproxy.hpp"
 #include "python2js.hpp"
 #include "runpython.hpp"
@@ -22,6 +23,7 @@ using emscripten::val;
 
 EMSCRIPTEN_BINDINGS(python) {
   emscripten::function("runPython", &runPython);
+  emscripten::function("pyimport", &pyimport);
   emscripten::class_<Py>("Py")
     .function<val>("call", &Py::call)
     .function<val>("getattr", &Py::getattr)

src/pyimport.cpp

+#include "js2python.hpp"
+#include "jsimport.hpp"
+#include "pyimport.hpp"
+#include "python2js.hpp"
+
+using emscripten::val;
+
+////////////////////////////////////////////////////////////
+// PyImport
+//
+// Makes `var foo = pyimport('foo')` work in Javascript.
+
+val pyimport(val name) {
+  PyObject *pyname = jsToPython(name);
+  PyObject *pyval = PyDict_GetItem(globals, pyname);
+  if (pyval == NULL) {
+    return pythonExcToJs();
+  }
+
+  return pythonToJs(pyval);
+}

src/pyimport.hpp

+#ifndef PYIMPORT_H
+#define PYIMPORT_H
+
+#include <emscripten.h>
+#include <emscripten/bind.h>
+#include <emscripten/val.h>
+
+emscripten::val pyimport(emscripten::val name);
+
+#endif /* PYIMPORT_H */