8000 Syntax error with * in function argument list · Issue #7338 · micropython/micropython · GitHub
[go: up one dir, main page]
Skip to content

Syntax error with * in function argument list #7338

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Closed
peterhinch opened this issue May 31, 2021 · 5 comments
Closed

Syntax error with * in function argument list #7338

peterhinch opened this issue May 31, 2021 · 5 comments

Comments

@peterhinch
Copy link
Contributor

This works as expected under CPython but throws a syntax error in MicroPython (RP2 and Unix build).

def bar():
    return 1, 2

class Foo:
    def __init__(self, x, y, z):
        print(x, y, z)

foo = Foo(*bar(), 3)

It seems that the * is interpreted as the specifier for kwonly args. Outcome:

Traceback (most recent call last):
  File "<stdin>", line 8, in <module>
SyntaxError: non-keyword arg after */**

A further observation. When I pasted this code in an mpremote session, a few seconds after the syntax error was reported mpremote fell over. Note that mpremote is as installed with pip3. Here is the complete session.

$ mpremote mount .
Local directory . is mounted at /remote
Connected to MicroPython at /dev/ttyACM0
Use Ctrl-] to exit this shell
>
MicroPython v1.15 on 2021-04-29; Raspberry Pi Pico with RP2040
Type "help()" for more information.
>>> 
paste mode; Ctrl-C to cancel, Ctrl-D to finish
=== Traceback (most recent call last):
===   File "<stdin>", line 8, in <module>
=== SyntaxError: non-keyword arg after */**
=== 
Traceback (most recent call last):
  File "<stdin>", line 1
SyntaxError: invalid syntax
>>> Traceback (most recent call last):
  File "/home/adminpete/.local/bin/mpremote", line 8, in <module>
    sys.exit(main())
  File "/home/adminpete/.local/lib/python3.8/site-packages/mpremote/main.py", line 1037, in main
    do_repl(pyb, args)
  File "/home/adminpete/.local/lib/python3.8/site-packages/mpremote/main.py", line 934, in do_repl
    do_repl_main_loop(pyb, console, console_out_write, file_to_inject)
  File "/home/adminpete/.local/lib/python3.8/site-packages/mpremote/main.py", line 874, in do_repl_main_loop
    pyb.soft_reset_with_mount(console_out_write)
  File "/home/adminpete/.local/lib/python3.8/site-packages/mpremote/main.py", line 644, in soft_reset_with_mount
    self.exec_(fs_hook_code)
  File "/home/adminpete/.local/lib/python3.8/site-packages/mpremote/pyboard.py", line 458, in exec_
    raise PyboardError("exception", ret, ret_err)
mpremote.pyboard.PyboardError: ('exception', b'\x18\x01\x03\x00\x00\x00/os\x18\x01\x06\x00\x00\x00/os.py\x18\x01\x07\x00\x00\x00/os.mpy\x18\x01\x03\x00\x00\x00/io\x18\x01\x06\x00\x00\x00/io.py\x18\x01\x07\x00\x00\x00/io.mpy\x18\x01', b'\x00\x00\x00/sys\x18\x01\x07\x00\x00\x00/sys.py\x18\x01\x08\x00\x00\x00/sys.mpy')
[adminpete@capybara]: /mnt/qnap2/data/Projects/MicroPython/micropython-micro-gui
@stinos
Copy link
Contributor
stinos commented May 31, 2021 •
edited
Loading

It seems that the * is interpreted as the specifier for kwonly args

It's actually just that MicroPython doesn't support normal arguments after unpacking other arguments (bey it keyword or not), ran into this many times already,always assuming it was documented behavior :) I.e. should be mentioned in the differences but isn't, as far as I can tell. See 1e70fda

@peterhinch
Copy link
Contributor Author
peterhinch commented May 31, 2021 •
edited
Loading

MicroPython seems to support subsequent keyword args, but barfs on positional ones. This example is of working code:

Button(writer, *self.locn(row, col), height = buttonheight, width = buttonwidth,
       textcolor = BLACK, bgcolor = color,
       text = text, shape = RECTANGLE,
       callback = back, args = (text,))

This variant of the test case works OK:

def bar():
    return 1, 2

class Foo:
    def __init__(self, x, y, z):
        print(x, y, z)

foo = Foo(*bar(), z = 3)  # Pass as a kwarg

@peterhinch peterhinch mentioned this issue May 31, 2021
Merged
@dlech
Copy link
Contributor
dlech commented May 31, 2021

This is one of the Python 3.5 features (namely PEP 448) that hasn't been implemented yet. See #1329 and #5807.

@dlech
Copy link
Contributor
dlech commented May 31, 2021

So tech 864B nically it documented:

MicroPython implements Python 3.4 and some select features of Python 3.5.

But of course it would be better if it was specifically called out. 😉

@peterhinch
Copy link
Contributor Author

OK, thanks both. I'd forgotten the PEP448 issue.

The behaviour of mpremote remains outstanding.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
Development

No branches or pull requests
3 participants
@dlech @stinos @peterhinch
0