Use importlib where available.

- This does change the shape of the `ply_dist` object inside util but
  users shouldn't normally and have no reason to depend on that.

Fixes #47

Author: metatoaster

src/calmjs/parse/tests/__init__.py

@@ -8,7 +8,6 @@
 from io import StringIO
 from os.path import basename
 from os.path import dirname
-from pkg_resources import get_distribution
 
 examples = {
     '/tmp/html4.js': dedent("""
@@ -63,14 +62,21 @@ def open(p, flag='r'):
         doctest.NORMALIZE_WHITESPACE | doctest.ELLIPSIS
     )
 
-    dist = get_distribution('calmjs.parse')
-    if dist:
-        if dist.has_metadata('PKG-INFO'):
-            pkgdesc = dist.get_metadata('PKG-INFO').replace('\r', '')
-        elif dist.has_metadata('METADATA'):
-            pkgdesc = dist.get_metadata('METADATA').replace('\r', '')
-        else:
-            pkgdesc = ''
+    try:
+        from importlib import metadata
+        pkgdesc = metadata.metadata('calmjs.parse').get('description')
+        pkgdesc = pkgdesc.replace('\r', '') if pkgdesc else ''
+    except ImportError:
+        from pkg_resources import get_distribution
+        dist = get_distribution('calmjs.parse')
+        if dist:
+            if dist.has_metadata('PKG-INFO'):
+                pkgdesc = dist.get_metadata('PKG-INFO').replace('\r', '')
+            elif dist.has_metadata('METADATA'):
+                pkgdesc = dist.get_metadata('METADATA').replace('\r', '')
+            else:
+                pkgdesc = ''
+
     pkgdesc_tests = [
         t for t in parser.parse(pkgdesc) if isinstance(t, doctest.Example)]
 

src/calmjs/parse/utils.py

@@ -9,20 +9,47 @@
 from os.path import normpath
 from os.path import relpath
 
+
+class _Distribution(object):
+    def __init__(self, project_name, version):
+        self.project_name = project_name
+        self.version = version
+
+
 try:
-    from pkg_resources import working_set
-    from pkg_resources import Requirement
-    ply_dist = working_set.find(Requirement.parse('ply'))
-    # note that for **extremely** ancient versions of setuptools, e.g.
-    # setuptools<0.6c11, or some very non-standard environment that does
-    # not include the required metadata (e.g. pyinstaller without the
-    # required metadata), will require the following workaround...
-    if ply_dist is None:  # pragma: no cover
-        from pkg_resources import Distribution
-        import ply
-        ply_dist = Distribution(project_name='ply', version=ply.__version__)
+    from importlib import metadata
+    try:
+        ply_version = metadata.version('ply')
+    except Exception:  # pragma: no cover
+        ply_dist = None
+    else:
+        ply_dist = _Distribution(project_name='ply', version=ply_version)
 except ImportError:  # pragma: no cover
-    ply_dist = None
+    try:
+        from pkg_resources import working_set
+        from pkg_resources import Requirement
+        ply_dist = working_set.find(Requirement.parse('ply'))
+        # note that for **extremely** ancient versions of setuptools, e.g.
+        # setuptools<0.6c11, or some very non-standard environment that does
+        # not include the required metadata (e.g. pyinstaller without the
+        # required metadata), will require the following workaround...
+        if ply_dist:
+            # convert to our private version class
+            ply_dist = _Distribution(
+                project_name='ply',
+                version=ply_dist.version,
+            )
+        else:
+            try:
+                import ply
+                ply_dist = _Distribution(
+                    project_name='ply',
+                    version=ply.__version__,
+                )
+            except ImportError:
+                ply_dist = None
+    except ImportError:  # pragma: no cover
+        ply_dist = None
 
 py_major = sys.version_info.major
 unicode = unicode if py_major < 3 else None  # noqa: F821