implement xml_mode() in a new irods.helpers module

irods/helpers/__init__.py

@@ -0,0 +1,50 @@
+import functools
+import inspect
+import types
+import contextlib
+from ..test.helpers import make_session as make_test_session
+from irods.message import (ET, XML_Parser_Type)
+
+
+# See https://stackoverflow.com/questions/67028108/overriding-function-signature-in-help-when-using-functools-wraps
+def update_func(f, func_name='', update_kwargs: dict = None):
+    """Based on http://stackoverflow.com/a/6528148/190597 (Glenn Maynard)"""
+    g = types.FunctionType(
+            code=f.__code__,
+            globals=f.__globals__.copy(),
+            name=f.__name__,
+            argdefs=f.__defaults__,
+            closure=f.__closure__
+    )
+
+    g = functools.update_wrapper(g, f)
+    g.__signature__ = inspect.signature(g)
+    g.__kwdefaults__ = (f.__kwdefaults__ or {}).copy()
+
+    # Adjust your arguments
+    for key, value in (update_kwargs or {}).items():
+        g.__kwdefaults__[key] = value
+        g.__signature__.parameters[key]._default = value
+
+    g.__name__ = func_name or g.__name__
+    return g
+
+
+make_session = update_func(make_test_session,
+                           update_kwargs = dict(test_server_version = False))
+
+
+@contextlib.contextmanager
+def xml_mode(s):
+    try:
+        if isinstance(s,str):
+            ET(getattr(XML_Parser_Type,s))        # e.g. xml_mode("QUASI_XML")
+        elif isinstance(s,(int,XML_Parser_Type)):
+            ET(s)                                 # e.g. xml_mode(2) or xml_mode(XML_Parser_Type.QUASI_XML)
+        else:
+            msg = "xml_mode argument must be a string (e.g. 'QUASI_XML'), XML_Parser_Type enum, or int."
+            raise ValueError(msg)
+        yield
+    finally:
+        ET(None)
+

irods/message/__init__.py

@@ -67,7 +67,7 @@ def __repr__(self):
     XML_Parser_Type.__members__ = {k:v for k,v in XML_Parser_Type.__dict__.items()
                                    if isinstance(v,XML_Parser_Type)}
 
-    PARSER_TYPE_STRINGS = {v:k for k,v in XML_Parser_Type.__members__.items() if v.value != 0}
+PARSER_TYPE_STRINGS = {v:k for k,v in XML_Parser_Type.__members__.items() if v.value != 0}
 
 # We maintain values on a per-thread basis of:
 #   - the server version with which we're communicating
@@ -111,6 +111,9 @@ def default_XML_parser(get_module = False):
     d = _default_XML
     return d if not get_module else _XML_parsers[d]
 
+def string_for_XML_parser(parser_enum):
+    return PARSER_TYPE_STRINGS[parser_enum]
+
 _XML_parsers = {
     XML_Parser_Type.STANDARD_XML : ET_xml,
     XML_Parser_Type.QUASI_XML : ET_quasi_xml,

irods/test/data_obj_test.py

@@ -1847,6 +1847,18 @@ def test_access_through_resc_hierarchy__243(self):
         finally:
             s.resources.remove('parent')
 
+    def test_temporary_xml_mode_change__issue_586(self): #dwm
+        from irods.message import (XML_Parser_Type, current_XML_parser, string_for_XML_parser)
+        from concurrent.futures import ThreadPoolExecutor
+        active_xml_for_thread = lambda : string_for_XML_parser(current_XML_parser())
+        from irods.helpers import xml_mode
+        self.assertEqual( active_xml_for_thread(), 'STANDARD_XML')
+        with xml_mode('QUASI_XML'):
+            # Test that this thread is the only one affected, and that in it we get 'QUASI_XML' when we call
+            # current_XML_parser(), i.e. the function used internally by ET() to retrieve the current parser module].
+            self.assertEqual( 'QUASI_XML',active_xml_for_thread())
+            self.assertEqual( 'STANDARD_XML',ThreadPoolExecutor(max_workers = 1).submit(active_xml_for_thread).result())
+
     def test_register_with_xml_special_chars(self):
         test_dir = helpers.irods_shared_tmp_dir()
         loc_server = self.sess.host in ('localhost', socket.gethostname())

irods/test/helpers.py

@@ -152,6 +152,18 @@ def recast(k):
 # Create a connection for test, based on ~/.irods environment by default.
 
 def make_session(test_server_version = True, **kwargs):
+    '''
+    Connect to an active iRODS server as determined by any client environment
+    file present at a standard location, and by any keyword arguments given.
+
+    Arguments:
+
+    test_server_version (True or False).  Raises iRODS_Server_Too_Recent if
+    the server connected to is more recent than the current python iRODS
+    client's advertised level of compatibility.
+
+    **kwargs: keyword arguments.  Fed directly to the iRODSSession constructor.
+    '''
     try:
         env_file = kwargs.pop('irods_env_file')
     except KeyError: