Exploratory commit for feedback, adds an async adapter, "send_robust" adapter, and positional call signature adapter.feature/receiver-adapter

3 files changed, 88 insertions, 0 deletions

diff --git a/blinker/_async.py b/blinker/_async.py
new file mode 100644
index 0000000..3bf87d3
--- /dev/null
+++ b/blinker/_async.py
@@ -0,0 +1,24 @@
+import asyncio
+
+from blinker.base import Signal
+
+
+try:
+    schedule = asyncio.ensure_future
+except AttributeError:
+    schedule = asyncio.async
+
+
+@asyncio.coroutine
+def _wrap_plain_value(value):
+    """Pass through a coroutine *value* or wrap a plain value."""
+    if asyncio.iscoroutine(value):
+        value = yield from value
+    return value
+
+
+def send_async(scheduler=schedule):
+    def adapter(receiver, sender, kwargs):
+        result = receiver(sender, **kwargs)
+        return scheduler(_wrap_plain_value(result))
+    return adapter
diff --git a/blinker/playground.py b/blinker/playground.py
new file mode 100644
index 0000000..8ed30fb
--- /dev/null
+++ b/blinker/playground.py
@@ -0,0 +1,20 @@
+import blinker
+
+
+def quash_exceptions(fn, sender, kwargs):
+    """Always call all receivers, collecting values or exceptions."""
+    try:
+        return fn(sender, **kwargs), None
+    except Exception as exc:
+        return None, exc
+
+
+def _adapt_xyz(fn, sender, kwargs):
+    return fn(sender, kwargs['x'], kwargs['y'], kwargs['z'])
+
+class PositionalSignal(blinker.Signal):
+    """Positional send and receive (x, y, z)"""
+    receiver_adapter = staticmethod(_adapt_xyz)
+
+    def send(self, sender, x, y, z):
+        return blinker.Signal.send(self, sender, x=x, y=y, z=z)
diff --git a/tests/test_async.py b/tests/test_async.py
new file mode 100644
index 0000000..fc01838
--- /dev/null
+++ b/tests/test_async.py
@@ -0,0 +1,44 @@
+import asyncio
+
+import blinker
+from blinker._async import send_async
+
+
+def test_send_async():
+    calls = []
+
+    @asyncio.coroutine
+    def receiver_a(sender):
+        calls.append(receiver_a)
+        return 'value a'
+
+    @asyncio.coroutine
+    def receiver_b(sender):
+        calls.append(receiver_b)
+        return 'value b'
+
+    def receiver_c(sender):
+        calls.append(receiver_c)
+        return 'value c'
+
+    sig = blinker.Signal(None, send_async())
+    sig.connect(receiver_a)
+    sig.connect(receiver_b)
+    sig.connect(receiver_c)
+
+    @asyncio.coroutine
+    def collect():
+        return sig.send()
+
+    loop = asyncio.get_event_loop()
+    results = loop.run_until_complete(collect())
+
+    expected = {
+        receiver_a: 'value a',
+        receiver_b: 'value b',
+        receiver_c: 'value c',
+        }
+
+    assert set(calls) == set(expected.keys())
+    collected_results = {v.result() for r, v in results}
+    assert collected_results == set(expected.values())