Move response/exception history to ClientResponse.qhistory

It is rarely necessary to access the history, and the tuple return value clutters the spec file code.

As a consequence, it's no longer possible to return None if an error occurred without losing the history.
To replace that, this also introduces a DummyClientResponse, which is kind of ClientResponse-like, has the same qhistory attribute, and evaluates to False when cast to bool (such that the intuitive `if response` works as expected).

qwarc/__init__.py

@@ -74,8 +74,7 @@ class Item:
 		verify_ssl: bool, whether the SSL/TLS certificate should be validated
 		timeout: int or float, how long the fetch may take at most in total (sending request until finishing reading the response)
 
-		Returns response (a ClientResponse object or None) and history (a tuple of (response, exception) tuples).
-			response can be None and history can be an empty tuple, depending on the circumstances (e.g. timeouts).
+		Returns response (a ClientResponse object or a qwarc.utils.DummyClientResponse object)
 		'''
 
 		#TODO: Rewrite using 'async with self.session.get'
@@ -126,13 +125,15 @@ class Item:
 				if response and exc is None and writeToWarc:
 					self.warc.write_client_response(response)
 				history.append((response, exc))
-				retResponse = response if exc is None else None
+				retResponse = response if exc is None else qwarc.utils.DummyClientResponse()
 				if action in (ACTION_SUCCESS, ACTION_IGNORE):
-					return retResponse, tuple(history)
+					retResponse.qhistory = tuple(history)
+					return retResponse
 				elif action == ACTION_FOLLOW_OR_SUCCESS:
 					redirectUrl = response.headers.get('Location') or response.headers.get('URI')
 					if not redirectUrl:
-						return retResponse, tuple(history)
+						retResponse.qhistory = tuple(history)
+						return retResponse
 					url = url.join(yarl.URL(redirectUrl))
 					if response.status in (301, 302, 303) and method == 'POST':
 						method = 'GET'
@@ -140,7 +141,8 @@ class Item:
 					attempt = 0
 				elif action == ACTION_RETRIES_EXCEEDED:
 					self.logger.error(f'Request for {url} failed {attempt} times')
-					return retResponse, tuple(history)
+					retResponse.qhistory = tuple(history)
+					return retResponse
 				elif action == ACTION_RETRY:
 					# Nothing to do, just go to the next cycle
 					pass

qwarc/aiohttp.py

@@ -84,6 +84,7 @@ class ClientResponse(aiohttp.client_reqrep.ClientResponse):
 		super().__init__(*args, **kwargs)
 		self._rawData = None
 		self._remoteAddress = None
+		self._qhistory = None # _history is used by aiohttp internally
 
 	async def start(self, connection, readUntilEof):
 		self._rawData = connection.protocol.rawData
@@ -110,8 +111,13 @@ class ClientResponse(aiohttp.client_reqrep.ClientResponse):
 	def remoteAddress(self):
 		return self._remoteAddress
 
-	def set_history(self, history):
-		self._history = history #FIXME: Uses private attribute of aiohttp.client_reqrep.ClientResponse
+	@property
+	def qhistory(self):
+		return self._qhistory
+
+	@qhistory.setter
+	def qhistory(self, history):
+		self._qhistory = history
 
 	def iter_all(self):
 		return itertools.chain(self.history, (self,))

qwarc/utils.py

@@ -260,3 +260,21 @@ class ReadonlyFileView:
 		if key == 'writable':
 			return False
 		return getattr(self._fp, key)
+
+
+class DummyClientResponse:
+	'''A ClientResponse-like object for when no actual ClientResponse is available. Always evaluates to False when cast to a bool.'''
+
+	def __init__(self):
+		self._qhistory = None
+
+	@property
+	def qhistory(self):
+		return self._qhistory
+
+	@qhistory.setter
+	def qhistory(self, history):
+		self._qhistory = history
+
+	def __bool__(self):
+		return False