From 885900df398eb8d24a3432003aab8f545e5d4a9f Mon Sep 17 00:00:00 2001
From: Marko Durkovic <marko@ternaris.com>
Date: Mon, 13 Sep 2021 10:49:57 +0200
Subject: [PATCH] Make reader1 API match reader2

---
 src/rosbags/rosbag1/reader.py | 15 +++++++++------
 src/rosbags/rosbag1/writer.py |  2 +-
 tests/test_reader1.py         |  3 ++-
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/rosbags/rosbag1/reader.py b/src/rosbags/rosbag1/reader.py
index 47223d07..31e3e4a0 100644
--- a/src/rosbags/rosbag1/reader.py
+++ b/src/rosbags/rosbag1/reader.py
@@ -55,8 +55,8 @@ class Connection(NamedTuple):
     cid: int
     topic: str
     msgtype: str
-    md5sum: str
     msgdef: str
+    md5sum: str
     callerid: Optional[str]
     latching: Optional[int]
     indexes: list
@@ -487,8 +487,8 @@ class Reader:
             conn,
             topic,
             normalize_msgtype(typ),
-            md5sum,
             msgdef,
+            md5sum,
             callerid,
             latching,
             [],
@@ -573,15 +573,15 @@ class Reader:
 
     def messages(
         self,
-        topics: Optional[Iterable[str]] = None,
+        connections: Iterable[Connection] = (),
         start: Optional[int] = None,
         stop: Optional[int] = None,
     ) -> Generator[tuple[Connection, int, bytes], None, None]:
         """Read messages from bag.
 
         Args:
-            topics: Iterable with topic names to filter for. An empty iterable
-                yields all messages.
+            connections: Iterable with connections to filter for. An empty
+                iterable disables filtering on connections.
             start: Yield only messages at or after this timestamp (ns).
             stop: Yield only messages before this timestamp (ns).
 
@@ -595,7 +595,10 @@ class Reader:
         if not self.bio:
             raise ReaderError('Rosbag is not open.')
 
-        indexes = [x.indexes for x in self.connections.values() if not topics or x.topic in topics]
+        if not connections:
+            connections = self.connections.values()
+
+        indexes = [x.indexes for x in connections]
         for entry in heapq.merge(*indexes):
             if start and entry.time < start:
                 continue
diff --git a/src/rosbags/rosbag1/writer.py b/src/rosbags/rosbag1/writer.py
index 650d3c52..51a5e6bd 100644
--- a/src/rosbags/rosbag1/writer.py
+++ b/src/rosbags/rosbag1/writer.py
@@ -245,8 +245,8 @@ class Writer:  # pylint: disable=too-many-instance-attributes
             len(self.connections),
             topic,
             denormalize_msgtype(msgtype),
-            md5sum,
             msgdef,
+            md5sum,
             callerid,
             latching,
             [],
diff --git a/tests/test_reader1.py b/tests/test_reader1.py
index f0a08124..5acbcf5b 100644
--- a/tests/test_reader1.py
+++ b/tests/test_reader1.py
@@ -254,7 +254,8 @@ def test_reader(tmp_path):  # pylint: disable=too-many-statements
         assert msgs[0][2] == b'MSGCONTENT5'
         assert msgs[1][2] == b'MSGCONTENT10'
 
-        msgs = list(reader.messages(['/topic0']))
+        connections = [x for x in reader.connections.values() if x.topic == '/topic0']
+        msgs = list(reader.messages(connections))
         assert len(msgs) == 1
         assert msgs[0][2] == b'MSGCONTENT10'