kopia lustrzana https://github.com/micropython/micropython-lib
102 wiersze
3.1 KiB
Markdown
102 wiersze
3.1 KiB
Markdown
# aiorepl
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This library provides "asyncio REPL", a simple REPL that can be used even
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while your program is running, allowing you to inspect program state, create
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tasks, and await asynchronous functions.
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This is inspired by Python's `asyncio` module when run via `python -m asyncio`.
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## Background
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The MicroPython REPL is unavailable while your program is running. This
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library runs a background REPL using the asyncio scheduler.
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Furthermore, it is not possible to `await` at the main REPL because it does
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not know about the asyncio scheduler.
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## Usage
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To use this library, you need to import the library and then start the REPL task.
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For example, in main.py:
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```py
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import uasyncio as asyncio
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import aiorepl
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async def demo():
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await asyncio.sleep_ms(1000)
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print("async demo")
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state = 20
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async def task1():
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while state:
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#print("task 1")
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await asyncio.sleep_ms(500)
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print("done")
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async def main():
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print("Starting tasks...")
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# Start other program tasks.
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t1 = asyncio.create_task(task1())
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# Start the aiorepl task.
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repl = asyncio.create_task(aiorepl.task())
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await asyncio.gather(t1, repl)
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asyncio.run(main())
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```
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An optional globals dictionary can be passed to `aiorepl.task()`, which allows
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you to specify what will be in scope for the REPL. By default it uses the
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globals dictionary from the `__main__` module, which is the same scope as the
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regular REPL (and `main.py`). In the example above, the REPL will be able to
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call the `demo()` function as well as get/set the `state` variable.
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You can also provide your own dictionary, e.g. `aiorepl.task({"obj": obj })`,
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or use the globals dict from the current module, e.g.
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`aiorepl.task(globals())`. Note that you cannot use a class instance's members
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dictionary, e.g. `aiorepl.task(obj.__dict__)`, as this is read-only in
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MicroPython.
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Instead of the regular `>>> ` prompt, the asyncio REPL will show `--> `.
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```
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--> 1+1
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2
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--> await demo()
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async demo
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--> state
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20
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--> import myapp.core
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--> state = await myapp.core.query_state()
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--> 1/0
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ZeroDivisionError: divide by zero
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--> def foo(x): return x + 1
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--> await asyncio.sleep(foo(3))
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-->
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```
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History is supported via the up/down arrow keys.
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## Cancellation
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During command editing (the "R" phase), pressing Ctrl-C will cancel the current command and display a new prompt, like the regular REPL.
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While a command is being executed, Ctrl-C will cancel the task that is executing the command. This will have no effect on blocking code (e.g. `time.sleep()`), but this should be rare in an asyncio-based program.
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Ctrl-D at the asyncio REPL command prompt will terminate the current event loop, which will stop the running program and return to the regular REPL.
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## Limitations
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The following features are unsupported:
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* Tab completion is not supported (also unsupported in `python -m asyncio`).
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* Multi-line continuation. However you can do single-line definitions of functions, see demo above.
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* Exception tracebacks. Only the exception type and message is shown, see demo above.
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* Emacs shortcuts (e.g. Ctrl-A, Ctrl-E, to move to start/end of line).
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* Unicode handling for input.
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