fixes #684

Author: jph00

fastcore/_modidx.py

@@ -534,7 +534,13 @@
                               'fastcore.xml.showtags': ('xml.html#showtags', 'fastcore/xml.py'),
                               'fastcore.xml.to_xml': ('xml.html#to_xml', 'fastcore/xml.py'),
                               'fastcore.xml.valmap': ('xml.html#valmap', 'fastcore/xml.py')},
-            'fastcore.xtras': { 'fastcore.xtras.ContextManagers': ('xtras.html#contextmanagers', 'fastcore/xtras.py'),
+            'fastcore.xtras': { 'fastcore.xtras.CachedAwaitable': ('xtras.html#cachedawaitable', 'fastcore/xtras.py'),
+                                'fastcore.xtras.CachedAwaitable.__await__': ('xtras.html#cachedawaitable.__await__', 'fastcore/xtras.py'),
+                                'fastcore.xtras.CachedAwaitable.__init__': ('xtras.html#cachedawaitable.__init__', 'fastcore/xtras.py'),
+                                'fastcore.xtras.CachedIter': ('xtras.html#cachediter', 'fastcore/xtras.py'),
+                                'fastcore.xtras.CachedIter.__init__': ('xtras.html#cachediter.__init__', 'fastcore/xtras.py'),
+                                'fastcore.xtras.CachedIter.__iter__': ('xtras.html#cachediter.__iter__', 'fastcore/xtras.py'),
+                                'fastcore.xtras.ContextManagers': ('xtras.html#contextmanagers', 'fastcore/xtras.py'),
                                 'fastcore.xtras.ContextManagers.__enter__': ('xtras.html#contextmanagers.__enter__', 'fastcore/xtras.py'),
                                 'fastcore.xtras.ContextManagers.__exit__': ('xtras.html#contextmanagers.__exit__', 'fastcore/xtras.py'),
                                 'fastcore.xtras.ContextManagers.__init__': ('xtras.html#contextmanagers.__init__', 'fastcore/xtras.py'),
@@ -621,6 +627,7 @@
                                 'fastcore.xtras.open_file': ('xtras.html#open_file', 'fastcore/xtras.py'),
                                 'fastcore.xtras.parse_env': ('xtras.html#parse_env', 'fastcore/xtras.py'),
                                 'fastcore.xtras.partial_format': ('xtras.html#partial_format', 'fastcore/xtras.py'),
+                                'fastcore.xtras.reawaitable': ('xtras.html#reawaitable', 'fastcore/xtras.py'),
                                 'fastcore.xtras.repo_details': ('xtras.html#repo_details', 'fastcore/xtras.py'),
                                 'fastcore.xtras.repr_dict': ('xtras.html#repr_dict', 'fastcore/xtras.py'),
                                 'fastcore.xtras.round_multiple': ('xtras.html#round_multiple', 'fastcore/xtras.py'),

fastcore/xtras.py

@@ -13,8 +13,8 @@
            'round_multiple', 'set_num_threads', 'join_path_file', 'autostart', 'EventTimer', 'stringfmt_names',
            'PartialFormatter', 'partial_format', 'utc2local', 'local2utc', 'trace', 'modified_env', 'ContextManagers',
            'shufflish', 'console_help', 'hl_md', 'type2str', 'dataclass_src', 'Unset', 'nullable_dc', 'make_nullable',
-           'flexiclass', 'asdict', 'is_typeddict', 'is_namedtuple', 'flexicache', 'time_policy', 'mtime_policy',
-           'timed_cache']
+           'flexiclass', 'asdict', 'is_typeddict', 'is_namedtuple', 'CachedIter', 'CachedAwaitable', 'reawaitable',
+           'flexicache', 'time_policy', 'mtime_policy', 'timed_cache']
 
 # %% ../nbs/03_xtras.ipynb
 from .imports import *
@@ -744,6 +744,29 @@ def is_namedtuple(cls):
     "`True` if `cls` is a namedtuple type"
     return issubclass(cls, tuple) and hasattr(cls, '_fields')
 
+# %% ../nbs/03_xtras.ipynb
+class CachedIter:
+    "Cache the result returned by an iterator"
+    def __init__(self, o): self.o,self.value = o,UNSET
+    def __iter__(self):
+        if self.value is UNSET: self.value = yield from self.o
+        return self.value
+
+# %% ../nbs/03_xtras.ipynb
+class CachedAwaitable:
+    "Cache the result from an awaitable"
+    def __init__(self, o): self.o,self.value = o,UNSET
+    def __await__(self):
+        if self.value is UNSET: self.value = yield from self.o.__await__()
+        return self.value
+
+# %% ../nbs/03_xtras.ipynb
+def reawaitable(func:callable):
+    "Wraps the result of an asynchronous function into an object which can be awaited more than once"
+    @wraps(func)
+    def _f(*args, **kwargs): return CachedAwaitable(func(*args, **kwargs))
+    return _f
+
 # %% ../nbs/03_xtras.ipynb
 def flexicache(*funcs, maxsize=128):
     "Like `lru_cache`, but customisable with policy `funcs`"