.. This document was generated by tools/gen-cpydiff.py

Modules
=======
Generated Sun 18 Apr 2021 15:09:42 UTC

array
-----

.. _cpydiff_modules_array_containment:

Looking for integer not implemented
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sample code::

    import array
    
    print(1 in array.array("B", b"12"))

+-------------+-------------------------------------------+
| CPy output: | uPy output:                               |
+-------------+-------------------------------------------+
| ::          | ::                                        |
|             |                                           |
|     False   |     Traceback (most recent call last):    |
|             |       File "<stdin>", line 9, in <module> |
|             |     NotImplementedError:                  |
+-------------+-------------------------------------------+

.. _cpydiff_modules_array_deletion:

Array deletion not implemented
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sample code::

    import array
    
    a = array.array("b", (1, 2, 3))
    del a[1]
    print(a)

+------------------------+-------------------------------------------------------------+
| CPy output:            | uPy output:                                                 |
+------------------------+-------------------------------------------------------------+
| ::                     | ::                                                          |
|                        |                                                             |
|     array('b', [1, 3]) |     Traceback (most recent call last):                      |
|                        |       File "<stdin>", line 10, in <module>                  |
|                        |     TypeError: 'array' object doesn't support item deletion |
+------------------------+-------------------------------------------------------------+

.. _cpydiff_modules_array_subscrstep:

Subscript with step != 1 is not yet implemented
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sample code::

    import array
    
    a = array.array("b", (1, 2, 3))
    print(a[3:2:2])

+----------------+---------------------------------------------------------------------------+
| CPy output:    | uPy output:                                                               |
+----------------+---------------------------------------------------------------------------+
| ::             | ::                                                                        |
|                |                                                                           |
|     array('b') |     Traceback (most recent call last):                                    |
|                |       File "<stdin>", line 10, in <module>                                |
|                |     NotImplementedError: only slices with step=1 (aka None) are supported |
+----------------+---------------------------------------------------------------------------+

builtins
--------

.. _cpydiff_builtin_next_arg2:

Second argument to next() is not implemented
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

**Cause:** MicroPython is optimised for code space.

**Workaround:** Instead of ``val = next(it, deflt)`` use::

    try:
        val = next(it)
    except StopIteration:
        val = deflt

Sample code::

    print(next(iter(range(0)), 42))

+-------------+-----------------------------------------------------------------------+
| CPy output: | uPy output:                                                           |
+-------------+-----------------------------------------------------------------------+
| ::          | ::                                                                    |
|             |                                                                       |
|     42      |     Traceback (most recent call last):                                |
|             |       File "<stdin>", line 12, in <module>                            |
|             |     TypeError: function takes 1 positional arguments but 2 were given |
+-------------+-----------------------------------------------------------------------+

deque
-----

.. _cpydiff_modules_deque:

Deque not implemented
~~~~~~~~~~~~~~~~~~~~~

**Workaround:** Use regular lists. micropython-lib has implementation of collections.deque.

Sample code::

    import collections
    
    D = collections.deque()
    print(D)

+---------------+-----------------------------------------------------------------+
| CPy output:   | uPy output:                                                     |
+---------------+-----------------------------------------------------------------+
| ::            | ::                                                              |
|               |                                                                 |
|     deque([]) |     Traceback (most recent call last):                          |
|               |       File "<stdin>", line 9, in <module>                       |
|               |     TypeError: function missing 2 required positional arguments |
+---------------+-----------------------------------------------------------------+

json
----

.. _cpydiff_modules_json_nonserializable:

JSON module does not throw exception when object is not serialisable
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sample code::

    import json
    
    a = bytes(x for x in range(256))
    try:
        z = json.dumps(a)
        x = json.loads(z)
        print("Should not get here")
    except TypeError:
        print("TypeError")

+---------------+-------------------------+
| CPy output:   | uPy output:             |
+---------------+-------------------------+
| ::            | ::                      |
|               |                         |
|     TypeError |     Should not get here |
+---------------+-------------------------+

os
--

.. _cpydiff_modules_os_environ:

``environ`` attribute is not implemented
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

**Workaround:** Use ``getenv``, ``putenv`` and ``unsetenv``

Sample code::

    import os
    
    try:
        print(os.environ.get("NEW_VARIABLE"))
        os.environ["NEW_VARIABLE"] = "VALUE"
        print(os.environ["NEW_VARIABLE"])
    except AttributeError:
        print("should not get here")
        print(os.getenv("NEW_VARIABLE"))
        os.putenv("NEW_VARIABLE", "VALUE")
        print(os.getenv("NEW_VARIABLE"))

+-------------+-------------------------+
| CPy output: | uPy output:             |
+-------------+-------------------------+
| ::          | ::                      |
|             |                         |
|     None    |     should not get here |
|     VALUE   |     None                |
|             |     VALUE               |
+-------------+-------------------------+

.. _cpydiff_modules_os_getenv:

``getenv`` returns actual value instead of cached value
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

**Cause:** The ``environ`` attribute is not implemented

Sample code::

    import os
    
    print(os.getenv("NEW_VARIABLE"))
    os.putenv("NEW_VARIABLE", "VALUE")
    print(os.getenv("NEW_VARIABLE"))

+-------------+-------------+
| CPy output: | uPy output: |
+-------------+-------------+
| ::          | ::          |
|             |             |
|     None    |     None    |
|     None    |     VALUE   |
+-------------+-------------+

.. _cpydiff_modules_os_getenv_argcount:

``getenv`` only allows one argument
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

**Workaround:** Test that the return value is ``None``

Sample code::

    import os
    
    try:
        print(os.getenv("NEW_VARIABLE", "DEFAULT"))
    except TypeError:
        print("should not get here")
        # this assumes NEW_VARIABLE is never an empty variable
        print(os.getenv("NEW_VARIABLE") or "DEFAULT")

+-------------+-------------------------+
| CPy output: | uPy output:             |
+-------------+-------------------------+
| ::          | ::                      |
|             |                         |
|     DEFAULT |     should not get here |
|             |     DEFAULT             |
+-------------+-------------------------+

struct
------

.. _cpydiff_modules_struct_fewargs:

Struct pack with too few args, not checked by uPy
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sample code::

    import struct
    
    try:
        print(struct.pack("bb", 1))
        print("Should not get here")
    except:
        print("struct.error")

+------------------+-------------------------+
| CPy output:      | uPy output:             |
+------------------+-------------------------+
| ::               | ::                      |
|                  |                         |
|     struct.error |     b'\x01\x00'         |
|                  |     Should not get here |
+------------------+-------------------------+

.. _cpydiff_modules_struct_manyargs:

Struct pack with too many args, not checked by uPy
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Sample code::

    import struct
    
    try:
        print(struct.pack("bb", 1, 2, 3))
        print("Should not get here")
    except:
        print("struct.error")

+------------------+-------------------------+
| CPy output:      | uPy output:             |
+------------------+-------------------------+
| ::               | ::                      |
|                  |                         |
|     struct.error |     b'\x01\x02'         |
|                  |     Should not get here |
+------------------+-------------------------+

sys
---

.. _cpydiff_modules_sys_stdassign:

Overriding sys.stdin, sys.stdout and sys.stderr not possible
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

**Cause:** They are stored in read-only memory.

Sample code::

    import sys
    
    sys.stdin = None
    print(sys.stdin)

+-------------+--------------------------------------------------------------+
| CPy output: | uPy output:                                                  |
+-------------+--------------------------------------------------------------+
| ::          | ::                                                           |
|             |                                                              |
|     None    |     Traceback (most recent call last):                       |
|             |       File "<stdin>", line 9, in <module>                    |
|             |     AttributeError: 'module' object has no attribute 'stdin' |
+-------------+--------------------------------------------------------------+