Merge pull request #2 from graingert/resync

backport from py3.10

pkgutil_resolve_name.py

@@ -33,22 +33,61 @@
 import importlib
 import re
 
-__version__ = "1.0.0"
+__version__ = "1.3.10"
 
-_DOTTED_WORDS = r'[a-z_]\w*(\.[a-z_]\w*)*'
-_NAME_PATTERN = re.compile('^({_DOTTED_WORDS})(:({_DOTTED_WORDS})?)?$'.format(_DOTTED_WORDS=_DOTTED_WORDS), re.I)
-del _DOTTED_WORDS
 
+_NAME_PATTERN = None
 
 def resolve_name(name):
+    """
+    Resolve a name to an object.
+
+    It is expected that `name` will be a string in one of the following
+    formats, where W is shorthand for a valid Python identifier and dot stands
+    for a literal period in these pseudo-regexes:
+
+    W(.W)*
+    W(.W)*:(W(.W)*)?
+
+    The first form is intended for backward compatibility only. It assumes that
+    some part of the dotted name is a package, and the rest is an object
+    somewhere within that package, possibly nested inside other objects.
+    Because the place where the package stops and the object hierarchy starts
+    can't be inferred by inspection, repeated attempts to import must be done
+    with this form.
+
+    In the second form, the caller makes the division point clear through the
+    provision of a single colon: the dotted name to the left of the colon is a
+    package to be imported, and the dotted name to the right is the object
+    hierarchy within that package. Only one import is needed in this form. If
+    it ends with the colon, then a module object is returned.
+
+    The function will return an object (which might be a module), or raise one
+    of the following exceptions:
+
+    ValueError - if `name` isn't in a recognised format
+    ImportError - if an import failed when it shouldn't have
+    AttributeError - if a failure occurred when traversing the object hierarchy
+                     within the imported package to get to the desired object)
+    """
+    global _NAME_PATTERN
+    if _NAME_PATTERN is None:
+        # Lazy import to speedup Python startup time
+        import re
+        dotted_words = r'(?!\d)(\w+)(\.(?!\d)(\w+))*'
+        _NAME_PATTERN = re.compile(f'^(?P<pkg>{dotted_words})'
+                                   f'(?P<cln>:(?P<obj>{dotted_words})?)?$',
+                                   re.UNICODE)
+
     m = _NAME_PATTERN.match(name)
     if not m:
-        raise ValueError('invalid format: {name!r}'.format(name=name))
-    groups = m.groups()
-    if groups[2]:
+        raise ValueError(f'invalid format: {name!r}')
+    gd = m.groupdict()
+    if gd.get('cln'):
         # there is a colon - a one-step import is all that's needed
-        mod = importlib.import_module(groups[0])
-        parts = groups[3].split('.') if groups[3] else []
+        mod = importlib.import_module(gd['pkg'])
+        parts = gd.get('obj')
+        parts = parts.split('.') if parts else []
     else:
         # no colon - have to iterate to find the package boundary
         parts = name.split('.')
@@ -57,7 +96,7 @@ def resolve_name(name):
         mod = importlib.import_module(modname)
         while parts:
             p = parts[0]
-            s = '{modname}.{p}'.format(modname=modname, p=p)
+            s = f'{modname}.{p}'
             try:
                 mod = importlib.import_module(s)
                 parts.pop(0)

pyproject.toml

@@ -11,3 +11,4 @@ maintainer = "Thomas Grainger"
 maintainer-email = "pkgutil-resolve-name@graingert.co.uk"
 home-page = "https://github.com/graingert/pkgutil-resolve-name"
 classifiers = ["License :: OSI Approved :: MIT License"]
+requires-python = ">=3.6"