Add --verbose option for cython magic

This fixes issue #1569

Cython/Build/IpythonMagic.py

@@ -53,8 +53,10 @@ import re
 import sys
 import time
 import copy
+import distutils.log
 import textwrap
 
+
 try:
     reload
 except NameError:   # Python 3
@@ -236,6 +238,11 @@ class CythonMagics(Magics):
         help=("Enable profile guided optimisation in the C compiler. "
               "Compiles the cell twice and executes it in between to generate a runtime profile.")
     )
+    @magic_arguments.argument(
+        '--verbose', dest='quiet', action='store_false', default=True,
+        help=("Print debug information like generated .c/.cpp file location "
+              "and exact gcc/g++ command invoked.")
+    )
     @cell_magic
     def cython(self, line, cell):
         """Compile and import everything from a Cython code cell.
@@ -282,7 +289,6 @@ class CythonMagics(Magics):
         args = magic_arguments.parse_argstring(self.cython, line)
         code = cell if cell.endswith('\n') else cell + '\n'
         lib_dir = os.path.join(get_ipython_cache_dir(), 'cython')
-        quiet = True
         key = (code, line, sys.version_info, sys.executable, cython_version)
 
         if not os.path.exists(lib_dir):
@@ -311,7 +317,7 @@ class CythonMagics(Magics):
 
         extension = None
         if need_cythonize:
-            extensions = self._cythonize(module_name, code, lib_dir, args, quiet=quiet)
+            extensions = self._cythonize(module_name, code, lib_dir, args, quiet=args.quiet)
             assert len(extensions) == 1
             extension = extensions[0]
             self._code_cache[key] = module_name
@@ -319,7 +325,8 @@ class CythonMagics(Magics):
             if args.pgo:
                 self._profile_pgo_wrapper(extension, lib_dir)
 
-        self._build_extension(extension, lib_dir, pgo_step_name='use' if args.pgo else None)
+        self._build_extension(extension, lib_dir, pgo_step_name='use' if args.pgo else None,
+                              quiet=args.quiet)
 
         module = imp.load_dynamic(module_name, module_path)
         self._import_all(module)
@@ -386,7 +393,7 @@ class CythonMagics(Magics):
         so_module_path = os.path.join(lib_dir, pgo_module_name + self.so_ext)
         imp.load_dynamic(pgo_module_name, so_module_path)
 
-    def _cythonize(self, module_name, code, lib_dir, args, quiet=False):
+    def _cythonize(self, module_name, code, lib_dir, args, quiet=True):
         pyx_file = os.path.join(lib_dir, module_name + '.pyx')
         pyx_file = py3compat.cast_bytes_py2(pyx_file, encoding=sys.getfilesystemencoding())
 
@@ -422,10 +429,17 @@ class CythonMagics(Magics):
         except CompileError:
             return None
 
-    def _build_extension(self, extension, lib_dir, temp_dir=None, pgo_step_name=None):
+    def _build_extension(self, extension, lib_dir, temp_dir=None, pgo_step_name=None, quiet=True):
         build_extension = self._get_build_extension(
             extension, lib_dir=lib_dir, temp_dir=temp_dir, pgo_step_name=pgo_step_name)
-        build_extension.run()
+        old_threshold = None
+        try:
+            if not quiet:
+                old_threshold = distutils.log.set_threshold(distutils.log.DEBUG)
+            build_extension.run()
+        finally:
+            if not quiet and old_threshold is not None:
+                distutils.log.set_threshold(old_threshold)
 
     def _add_pgo_flags(self, build_extension, step_name, temp_dir):
         compiler_type = build_extension.compiler.compiler_type

Cython/Build/Tests/TestIpythonMagic.py

@@ -5,6 +5,8 @@
 
 import os
 import sys
+from contextlib import contextmanager
+from Cython.Build import IpythonMagic
 
 try:
     from IPython.testing.globalipapp import get_ipython
@@ -139,3 +141,43 @@ x = sin(0.0)
         ip.user_ns['x'] = 1
         ip.run_cell_magic('cython', '-l m', code)
         self.assertEqual(ip.user_ns['x'], 0)
+
+
+    def test_cython_verbose(self):
+        ip.run_cell_magic('cython', '--verbose', code)
+        ip.ex('g = f(10)')
+        self.assertEqual(ip.user_ns['g'], 20.0)
+
+    def test_cython_verbose_thresholds(self):
+        @contextmanager
+        def mock_distutils():
+            class MockLog:
+                DEBUG = 1
+                INFO = 2
+                thresholds = [INFO]
+
+                def set_threshold(self, val):
+                    self.thresholds.append(val)
+                    return self.thresholds[-2]
+
+
+            new_log = MockLog()
+            old_log = IpythonMagic.distutils.log
+            try:
+                IpythonMagic.distutils.log = new_log
+                yield new_log
+            finally:
+                IpythonMagic.distutils.log = old_log
+
+        with mock_distutils() as verbose_log:
+            ip.run_cell_magic('cython', '--verbose', code)
+            ip.ex('g = f(10)')
+        self.assertEqual(ip.user_ns['g'], 20.0)
+        self.assertEquals([verbose_log.INFO, verbose_log.DEBUG, verbose_log.INFO],
+                          verbose_log.thresholds)
+
+        with mock_distutils() as normal_log:
+            ip.run_cell_magic('cython', '', code)
+            ip.ex('g = f(10)')
+        self.assertEqual(ip.user_ns['g'], 20.0)
+        self.assertEquals([normal_log.INFO], normal_log.thresholds)