examples: add coroutine_pipe

examples/coroutine_pipe.py

@@ -0,0 +1,68 @@
+"""
+Inserting `tqdm` as a "pipe" in a chain of coroutines.
+Not to be confused with `asyncio.coroutine`.
+"""
+from functools import wraps
+from tqdm.auto import tqdm
+
+
+def autonext(func):
+    @wraps(func)
+    def inner(*args, **kwargs):
+        res = func(*args, **kwargs)
+        next(res)
+        return res
+    return inner
+
+
+@autonext
+def tqdm_pipe(target, **tqdm_kwargs):
+    """
+    Coroutine chain pipe `send()`ing to `target`.
+
+    This:
+    >>> r = receiver()
+    >>> p = producer(r)
+    >>> next(r)
+    >>> next(p)
+
+    Becomes:
+    >>> r = receiver()
+    >>> t = tqdm.pipe(r)
+    >>> p = producer(t)
+    >>> next(r)
+    >>> next(p)
+    """
+    with tqdm(**tqdm_kwargs) as pbar:
+        while True:
+            obj = (yield)
+            target.send(obj)
+            pbar.update()
+
+
+def source(target):
+    for i in ["foo", "bar", "baz", "pythonista", "python", "py"]:
+        target.send(i)
+    target.close()
+
+
+@autonext
+def grep(pattern, target):
+    while True:
+        line = (yield)
+        if pattern in line:
+            target.send(line)
+
+
+@autonext
+def sink():
+    while True:
+        line = (yield)
+        tqdm.write(line)
+
+
+if __name__ == "__main__":
+    source(
+        tqdm_pipe(
+            grep('python',
+                 sink())))