[CLN] resolve circular Period dependency, prepare setup.py (#21854)

Author: jbrockmendel

pandas/_libs/__init__.py

@@ -1,9 +1,5 @@
 # -*- coding: utf-8 -*-
 # flake8: noqa
 
-from .tslibs import iNaT, NaT, Timestamp, Timedelta, OutOfBoundsDatetime
-
-# TODO
-# period is directly dependent on tslib and imports python
-# modules, so exposing Period as an alias is currently not possible
-# from period import Period
+from .tslibs import (
+    iNaT, NaT, Timestamp, Timedelta, OutOfBoundsDatetime, Period)

pandas/_libs/tslibs/__init__.py

@@ -4,5 +4,6 @@
 from .conversion import normalize_date, localize_pydatetime, tz_convert_single
 from .nattype import NaT, iNaT
 from .np_datetime import OutOfBoundsDatetime
+from .period import Period, IncompatibleFrequency
 from .timestamps import Timestamp
 from .timedeltas import delta_to_nanoseconds, ints_to_pytimedelta, Timedelta

pandas/_libs/tslibs/resolution.pyx

@@ -28,8 +28,6 @@ from timestamps import Timestamp
 
 from pandas._libs.properties import cache_readonly
 
-from pandas.core.algorithms import unique  # TODO: Avoid this non-cython import
-
 # ----------------------------------------------------------------------
 # Constants
 
@@ -574,6 +572,10 @@ cdef class _FrequencyInferer(object):
         if len(self.ydiffs) > 1:
             return None
 
+        # lazy import to prevent circularity
+        # TODO: Avoid non-cython dependency
+        from pandas.core.algorithms import unique
+
         if len(unique(self.fields['M'])) > 1:
             return None
 
@@ -618,6 +620,10 @@ cdef class _FrequencyInferer(object):
         #     if not lib.ismember(wdiffs, set([4, 5, -47, -49, -48])).all():
         #         return None
 
+        # lazy import to prevent circularity
+        # TODO: Avoid non-cython dependency
+        from pandas.core.algorithms import unique
+
         weekdays = unique(self.index.weekday)
         if len(weekdays) > 1:
             return None

pandas/tests/tslibs/test_api.py

@@ -24,6 +24,8 @@ def test_namespace():
     api = ['NaT',
            'iNaT',
            'OutOfBoundsDatetime',
+           'Period',
+           'IncompatibleFrequency',
            'Timedelta',
            'Timestamp',
            'delta_to_nanoseconds',

setup.py

@@ -24,23 +24,6 @@ def is_platform_windows():
     return sys.platform == 'win32' or sys.platform == 'cygwin'
 
 
-def is_platform_linux():
-    return sys.platform == 'linux2'
-
-
-def is_platform_mac():
-    return sys.platform == 'darwin'
-
-
-min_cython_ver = '0.28.2'
-try:
-    import Cython
-    ver = Cython.__version__
-    _CYTHON_INSTALLED = ver >= LooseVersion(min_cython_ver)
-except ImportError:
-    _CYTHON_INSTALLED = False
-
-
 min_numpy_ver = '1.9.0'
 setuptools_kwargs = {
     'install_requires': [
@@ -53,24 +36,29 @@ def is_platform_mac():
 }
 
 
+min_cython_ver = '0.28.2'
+try:
+    import Cython
+    ver = Cython.__version__
+    _CYTHON_INSTALLED = ver >= LooseVersion(min_cython_ver)
+except ImportError:
+    _CYTHON_INSTALLED = False
+
+# The import of Extension must be after the import of Cython, otherwise
+# we do not get the appropriately patched class.
+# See https://cython.readthedocs.io/en/latest/src/reference/compilation.html
 from distutils.extension import Extension  # noqa:E402
 from distutils.command.build import build  # noqa:E402
-from distutils.command.build_ext import build_ext as _build_ext  # noqa:E402
 
 try:
     if not _CYTHON_INSTALLED:
         raise ImportError('No supported version of Cython installed.')
-    try:
-        from Cython.Distutils.old_build_ext import old_build_ext as _build_ext  # noqa:F811,E501
-    except ImportError:
-        # Pre 0.25
-        from Cython.Distutils import build_ext as _build_ext
+    from Cython.Distutils.old_build_ext import old_build_ext as _build_ext
     cython = True
 except ImportError:
+    from distutils.command.build_ext import build_ext as _build_ext
     cython = False
-
-
-if cython:
+else:
     try:
         try:
             from Cython import Tempita as tempita
@@ -103,27 +91,30 @@ def is_platform_mac():
 
 
 class build_ext(_build_ext):
-    def build_extensions(self):
+    @classmethod
+    def render_templates(cls, pxifiles):
+        for pxifile in pxifiles:
+            # build pxifiles first, template extension must be .pxi.in
+            assert pxifile.endswith('.pxi.in')
+            outfile = pxifile[:-3]
 
-        # if builing from c files, don't need to
-        # generate template output
-        if cython:
-            for pxifile in _pxifiles:
-                # build pxifiles first, template extension must be .pxi.in
-                assert pxifile.endswith('.pxi.in')
-                outfile = pxifile[:-3]
-
-                if (os.path.exists(outfile) and
-                        os.stat(pxifile).st_mtime < os.stat(outfile).st_mtime):
-                    # if .pxi.in is not updated, no need to output .pxi
-                    continue
+            if (os.path.exists(outfile) and
+                    os.stat(pxifile).st_mtime < os.stat(outfile).st_mtime):
+                # if .pxi.in is not updated, no need to output .pxi
+                continue
 
-                with open(pxifile, "r") as f:
-                    tmpl = f.read()
-                pyxcontent = tempita.sub(tmpl)
+            with open(pxifile, "r") as f:
+                tmpl = f.read()
+            pyxcontent = tempita.sub(tmpl)
 
-                with open(outfile, "w") as f:
-                    f.write(pyxcontent)
+            with open(outfile, "w") as f:
+                f.write(pyxcontent)
+
+    def build_extensions(self):
+        # if building from c files, don't need to
+        # generate template output
+        if cython:
+            self.render_templates(_pxifiles)
 
         numpy_incl = pkg_resources.resource_filename('numpy', 'core/include')
 
@@ -360,7 +351,6 @@ def run(self):
 class CheckingBuildExt(build_ext):
     """
     Subclass build_ext to get clearer report if Cython is necessary.
-
     """
 
     def check_cython_extensions(self, extensions):
@@ -379,9 +369,11 @@ def build_extensions(self):
 
 
 class CythonCommand(build_ext):
-    """Custom distutils command subclassed from Cython.Distutils.build_ext
+    """
+    Custom distutils command subclassed from Cython.Distutils.build_ext
     to compile pyx->c, and stop there. All this does is override the
-    C-compile method build_extension() with a no-op."""
+    C-compile method build_extension() with a no-op.
+    """
     def build_extension(self, ext):
         pass
 
@@ -445,7 +437,6 @@ def srcpath(name=None, suffix='.pyx', subdir='src'):
     lib_depends.append('pandas/_libs/src/util.pxd')
 else:
     lib_depends = []
-    plib_depends = []
 
 common_include = ['pandas/_libs/src/klib', 'pandas/_libs/src']
 
@@ -471,8 +462,6 @@ def pxd(name):
 
 tseries_depends = np_datetime_headers + ['pandas/_libs/tslibs/np_datetime.pxd']
 
-# some linux distros require it
-libraries = ['m'] if not is_platform_windows() else []
 
 ext_data = {
     '_libs.algos': {