- utio.io: added mkstemp function

mkstemp returns a temporary file.
The returned instance can be treated like a str and an
instance that is returned by tempfile.NamedTemporaryFile.
For example, it can be passed to os.stat and the temporary
file is automatically deleted, if the instance is garbage
collected.

osc2/util/io.py

@@ -9,7 +9,7 @@
 import shutil
 from tempfile import NamedTemporaryFile, mkdtemp as orig_mkdtemp
 
-from osc2.util.delegation import StringifiedDelegator
+from osc2.util.delegation import StringifiedDelegator, Delegator
 
 
 __all__ = ['copy_file', 'iter_read']
@@ -318,3 +318,30 @@ def mkdtemp(*args, **kwargs):
     return TemporaryEntityDelegator.create(
         TemporaryDirectory(*args, **kwargs)
     )
+
+
+def mkstemp(*args, **kwargs):
+    """Returns a temporary file.
+
+    The returned instance can be treated like a str and an
+    instance that is returned by tempfile.NamedTemporaryFile.
+    For example, it can be passed to os.stat and the temporary
+    file is automatically deleted, if the instance is garbage
+    collected.
+
+    *args and **kwargs are passed to the tempfile.NamedTemporaryFile
+    function.
+
+    """
+    # the instance, which is returned by the NamedTemporaryFile call,
+    # has no suitable __str__ method; thus, we provide one via yet
+    # another delegator
+    class NamedTemporaryFileDelegator(Delegator):
+        def __str__(self):
+            return self._delegate.name
+
+    # delegation is as follows:
+    # TemporaryEntityDelegator -> NamedTemporaryFileDelegator -> tmpfile
+    return TemporaryEntityDelegator.create(
+        NamedTemporaryFileDelegator(NamedTemporaryFile(*args, **kwargs))
+    )