# Syntax

Generated Wed 19 Jul 2023 21:24:18 UTC

## Argument unpacking does not work if the argument being unpacked is the nth or greater argument where n is the number of bits in an MP_SMALL_INT.

Cause: The implementation uses an MP_SMALL_INT to flag args that need to be unpacked.

Workaround: Use fewer arguments.

Sample code:

    def example(*args):
        print(len(args))

    MORE = ["a", "b", "c"]

    example(
        0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
        16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
        32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
        48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
        *MORE,
    )

CPy output: | uPy output:
    67
    /bin/sh: 1: ../ports/unix/build-standard/micropython: not found

### Operators

## MicroPython allows using := to assign to the variable of a comprehension, CPython raises a SyntaxError.

Cause: MicroPython is optimised for code size and doesn’t check this case.

Workaround: Do not rely on this behaviour if writing CPython compatible code.

Sample code:

    print([i := -1 for i in range(4)])

CPy output: | uPy output:
      File "<stdin>", line 7
    SyntaxError: assignment expression cannot rebind comprehension iteration variable 'i'
    /bin/sh: 1: ../ports/unix/build-standard/micropython: not found

### Spaces

## uPy requires spaces between literal numbers and keywords, CPy doesn’t

Sample code:

    try:
        print(eval("1and 0"))
    except SyntaxError:
        print("Should have worked")
    try:
        print(eval("1or 0"))
    except SyntaxError:
        print("Should have worked")
    try:
        print(eval("1if 1else 0"))
    except SyntaxError:
        print("Should have worked")

CPy output: | uPy output:
    0
    1
    1
    /bin/sh: 1: ../ports/unix/build-standard/micropython: not found

### Unicode

## Unicode name escapes are not implemented

Sample code:

    print("\N{LATIN SMALL LETTER A}")

CPy output: | uPy output:
    a
    /bin/sh: 1: ../ports/unix/build-standard/micropython: not found

Language and External Links

Language
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External links
  openmv.io
  forums.openmv.io
  github.com/openmv/openmv
  micropython.org
  forum.micropython.org
  github.com/micropython/micropython