track embedded python distribution

python/gevent/_util.py

@@ -0,0 +1,106 @@
+# -*- coding: utf-8 -*-
+"""
+internal gevent utilities, not for external use.
+"""
+
+from __future__ import print_function, absolute_import, division
+
+from gevent._compat import iteritems
+
+
+class _NONE(object):
+    """
+    A special object you must never pass to any gevent API.
+    Used as a marker object for keyword arguments that cannot have the
+    builtin None (because that might be a valid value).
+    """
+    __slots__ = ()
+
+    def __repr__(self):
+        return '<default value>'
+
+_NONE = _NONE()
+
+def copy_globals(source,
+                 globs,
+                 only_names=None,
+                 ignore_missing_names=False,
+                 names_to_ignore=(),
+                 dunder_names_to_keep=('__implements__', '__all__', '__imports__'),
+                 cleanup_globs=True):
+    """
+    Copy attributes defined in `source.__dict__` to the dictionary in globs
+    (which should be the caller's globals()).
+
+    Names that start with `__` are ignored (unless they are in
+    *dunder_names_to_keep*). Anything found in *names_to_ignore* is
+    also ignored.
+
+    If *only_names* is given, only those attributes will be considered.
+    In this case, *ignore_missing_names* says whether or not to raise an AttributeError
+    if one of those names can't be found.
+
+    If cleanup_globs has a true value, then common things imported but not used
+    at runtime are removed, including this function.
+
+    Returns a list of the names copied
+    """
+    if only_names:
+        if ignore_missing_names:
+            items = ((k, getattr(source, k, _NONE)) for k in only_names)
+        else:
+            items = ((k, getattr(source, k)) for k in only_names)
+    else:
+        items = iteritems(source.__dict__)
+
+    copied = []
+    for key, value in items:
+        if value is _NONE:
+            continue
+        if key in names_to_ignore:
+            continue
+        if key.startswith("__") and key not in dunder_names_to_keep:
+            continue
+        globs[key] = value
+        copied.append(key)
+
+    if cleanup_globs:
+        if 'copy_globals' in globs:
+            del globs['copy_globals']
+
+    return copied
+
+class Lazy(object):
+    """
+    A non-data descriptor used just like @property. The
+    difference is the function value is assigned to the instance
+    dict the first time it is accessed and then the function is never
+    called agoin.
+    """
+    def __init__(self, func):
+        self.data = (func, func.__name__)
+
+    def __get__(self, inst, class_):
+        if inst is None:
+            return self
+
+        func, name = self.data
+        value = func(inst)
+        inst.__dict__[name] = value
+        return value
+
+class readproperty(object):
+    """
+    A non-data descriptor like @property. The difference is that
+    when the property is assigned to, it is cached in the instance
+    and the function is not called on that instance again.
+    """
+
+    def __init__(self, func):
+        self.func = func
+
+    def __get__(self, inst, class_):
+        if inst is None:
+            return self
+
+        return self.func(inst)