Rendezvous: Difference between revisions
A Python implementation
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2: And mounting its back,
Humpty Dumpty: Out of Ink!</pre>
=={{header|Python}}==
{{works with|Python|3.7}}
<lang python>"""An approximation of the rendezvous pattern found in Ada using asyncio."""
from __future__ import annotations
import asyncio
import sys
from typing import Optional
from typing import TextIO
class OutOfInkError(Exception):
"""Exception raised when a printer is out of ink."""
class Printer:
def __init__(self, name: str, backup: Optional[Printer]):
self.name = name
self.backup = backup
self.ink_level: int = 5
self.output_stream: TextIO = sys.stdout
async def print(self, msg):
if self.ink_level <= 0:
if self.backup:
await self.backup.print(msg)
else:
raise OutOfInkError(self.name)
else:
self.ink_level -= 1
self.output_stream.write(f"({self.name}): {msg}\n")
async def main():
reserve = Printer("reserve", None)
main = Printer("main", reserve)
humpty_lines = [
"Humpty Dumpty sat on a wall.",
"Humpty Dumpty had a great fall.",
"All the king's horses and all the king's men,",
"Couldn't put Humpty together again.",
]
goose_lines = [
"Old Mother Goose,",
"When she wanted to wander,",
"Would ride through the air,",
"On a very fine gander.",
"Jack's mother came in,",
"And caught the goose soon,",
"And mounting its back,",
"Flew up to the moon.",
]
async def print_humpty():
for line in humpty_lines:
try:
task = asyncio.Task(main.print(line))
await task
except OutOfInkError:
print("\t Humpty Dumpty out of ink!")
break
async def print_goose():
for line in goose_lines:
try:
task = asyncio.Task(main.print(line))
await task
except OutOfInkError:
print("\t Mother Goose out of ink!")
break
await asyncio.gather(print_goose(), print_humpty())
if __name__ == "__main__":
asyncio.run(main(), debug=True)</lang>
{{out}}
<pre>
(main): Old Mother Goose,
(main): Humpty Dumpty sat on a wall.
(main): When she wanted to wander,
(main): Humpty Dumpty had a great fall.
(main): Would ride through the air,
(reserve): All the king's horses and all the king's men,
(reserve): On a very fine gander.
(reserve): Couldn't put Humpty together again.
(reserve): Jack's mother came in,
(reserve): And caught the goose soon,
Mother Goose out of ink!</pre>
=={{header|Racket}}==
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