GeezerVison is showing github.com — replace `array.__reduce__` to `array.__reduce_ex__` · Issue #3876 · RustPython/RustPython
replace array.__reduce__ to array.__reduce_ex__ #3876DescriptionFeature
In rustPython's array pickling, reduce is used.
However, reduce_ex is used in cPython's pickle.
I think we should implement reduce_ex in the array and use reduce_ex for picking.
Execution Result
There is no related python documentation, so I will attach the execution result.
 Reacted by fanninpm and Snowapril Activitychanged the title [-]Requires implementation of array reduce_ex[/-] [+]Requires implementation of array `reduce_ex`[/+] on Jul 13, 2022Yaminyam commented on Jul 13, 2022 Although the #3611 issue mentions the implementation of __reduce_ex__, the actual tasks include only the implementation of __reduce_ex__.
However, when pickle dump is performed, __reduce_ex__ is executed as in this issue, so the implementation of __reduce_ex__ seems to be necessary a lot.
In particular, there are many cases where it is executed only with __reduce_ex__ without an implementation of __reduce__, such as array and list. changed the title [-]Requires implementation of array `reduce_ex`[/-] [+]replace `array.__reduce__` to `array.__reduce_ex__`[/+] on Jul 13, 2022fanninpm commented on Jul 13, 2022 This is likely why @Snowapril mentioned arrayiterator.__reduce__ in #3611. It's important to note that arrayiterator is distinct from array in that arrayiterator is what happens when you do this1:
>>> import array
>>> a = array.array('i', [1, 2, 3])
>>> type(iter(a))
<class 'arrayiterator'>
What methods does arrayiterator implement?
>>> help(iter(a))
Help on arrayiterator object:
class arrayiterator(object)
| Methods defined here:
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __iter__(self, /)
| Implement iter(self).
|
| __next__(self, /)
| Implement next(self).
|
| __reduce__(self, /)
| Return state information for pickling.
|
| __setstate__(self, state, /)
| Set state information for unpickling.
By contrast, what methods does array implement?
>>> help(a)
Help on array object:
class array(builtins.object)
| array(typecode [, initializer]) -> array
|
| Return a new array whose items are restricted by typecode, and
| initialized from the optional initializer value, which must be a list,
| string or iterable over elements of the appropriate type.
|
| Arrays represent basic values and behave very much like lists, except
| the type of objects stored in them is constrained. The type is specified
| at object creation time by using a type code, which is a single character.
| The following type codes are defined:
|
| Type code C Type Minimum size in bytes
| 'b' signed integer 1
| 'B' unsigned integer 1
| 'u' Unicode character 2 (see note)
| 'h' signed integer 2
| 'H' unsigned integer 2
| 'i' signed integer 2
| 'I' unsigned integer 2
| 'l' signed integer 4
| 'L' unsigned integer 4
| 'q' signed integer 8 (see note)
| 'Q' unsigned integer 8 (see note)
| 'f' floating point 4
| 'd' floating point 8
|
| NOTE: The 'u' typecode corresponds to Python's unicode character. On
| narrow builds this is 2-bytes on wide builds this is 4-bytes.
|
| NOTE: The 'q' and 'Q' type codes are only available if the platform
| C compiler used to build Python supports 'long long', or, on Windows,
| '__int64'.
|
| Methods:
|
| append() -- append a new item to the end of the array
| buffer_info() -- return information giving the current memory info
| byteswap() -- byteswap all the items of the array
| count() -- return number of occurrences of an object
| extend() -- extend array by appending multiple elements from an iterable
| fromfile() -- read items from a file object
| fromlist() -- append items from the list
| frombytes() -- append items from the string
| index() -- return index of first occurrence of an object
| insert() -- insert a new item into the array at a provided position
| pop() -- remove and return item (default last)
| remove() -- remove first occurrence of an object
| reverse() -- reverse the order of the items in the array
| tofile() -- write all items to a file object
| tolist() -- return the array converted to an ordinary list
| tobytes() -- return the array converted to a string
|
| Attributes:
|
| typecode -- the typecode character used to create the array
| itemsize -- the length in bytes of one array item
|
| Methods defined here:
|
| __add__(self, value, /)
| Return self+value.
|
| __contains__(self, key, /)
| Return key in self.
|
| __copy__(self, /)
| Return a copy of the array.
|
| __deepcopy__(self, unused, /)
| Return a copy of the array.
|
| __delitem__(self, key, /)
| Delete self[key].
|
| __eq__(self, value, /)
| Return self==value.
|
| __ge__(self, value, /)
| Return self>=value.
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __getitem__(self, key, /)
| Return self[key].
|
| __gt__(self, value, /)
| Return self>value.
|
| __iadd__(self, value, /)
| Implement self+=value.
|
| __imul__(self, value, /)
| Implement self*=value.
|
| __iter__(self, /)
| Implement iter(self).
|
| __le__(self, value, /)
| Return self<=value.
|
| __len__(self, /)
| Return len(self).
|
| __lt__(self, value, /)
| Return self<value.
|
| __mul__(self, value, /)
| Return self*value.
|
| __ne__(self, value, /)
| Return self!=value.
|
| __reduce_ex__(self, value, /)
| Return state information for pickling.
|
| __repr__(self, /)
| Return repr(self).
|
| __rmul__(self, value, /)
| Return value*self.
|
| __setitem__(self, key, value, /)
| Set self[key] to value.
|
| __sizeof__(self, /)
| Size of the array in memory, in bytes.
|
| append(self, v, /)
| Append new value v to the end of the array.
|
| buffer_info(self, /)
| Return a tuple (address, length) giving the current memory address and the length in items of the buffer used to hold array's contents.
|
| The length should be multiplied by the itemsize attribute to calculate
| the buffer length in bytes.
|
| byteswap(self, /)
| Byteswap all items of the array.
|
| If the items in the array are not 1, 2, 4, or 8 bytes in size, RuntimeError is
| raised.
|
| count(self, v, /)
| Return number of occurrences of v in the array.
|
| extend(self, bb, /)
| Append items to the end of the array.
|
| frombytes(self, buffer, /)
| Appends items from the string, interpreting it as an array of machine values, as if it had been read from a file using the fromfile() method).
|
| fromfile(self, f, n, /)
| Read n objects from the file object f and append them to the end of the array.
|
| fromlist(self, list, /)
| Append items to array from list.
|
| fromunicode(self, ustr, /)
| Extends this array with data from the unicode string ustr.
|
| The array must be a unicode type array; otherwise a ValueError is raised.
| Use array.frombytes(ustr.encode(...)) to append Unicode data to an array of
| some other type.
|
| index(self, v, /)
| Return index of first occurrence of v in the array.
|
| insert(self, i, v, /)
| Insert a new item v into the array before position i.
|
| pop(self, i=-1, /)
| Return the i-th element and delete it from the array.
|
| i defaults to -1.
| i defaults to -1.
|
| remove(self, v, /)
| Remove the first occurrence of v in the array.
|
| reverse(self, /)
| Reverse the order of the items in the array.
|
| tobytes(self, /)
| Convert the array to an array of machine values and return the bytes representation.
|
| tofile(self, f, /)
| Write all items (as machine values) to the file object f.
|
| tolist(self, /)
| Convert array to an ordinary list with the same items.
|
| tounicode(self, /)
| Extends this array with data from the unicode string ustr.
|
| Convert the array to a unicode string. The array must be a unicode type array;
| otherwise a ValueError is raised. Use array.tobytes().decode() to obtain a
| unicode string from an array of some other type.
|
| ----------------------------------------------------------------------
| Static methods defined here:
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| itemsize
| the size, in bytes, of one array item
|
| typecode
| the typecode character used to create the array
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| __hash__ = None
Does this help?
Footnotes
-
The following examples were run with CPython 3.9, but CPython 3.10 should yield similar results. ↩
Reacted by Snowapril, Jeong, YunWon and Sion Kang Snowapril commented on Jul 15, 2022 fanninpm commented on Jul 15, 2022 @qingshi163 implemented __reduce__ for array.array in #3064. I'm a little surprised that this discrepancy wasn't caught at the time.
@maong0927 Thanks for bringing this to our attention. As @Snowapril points out, the fix seems simple. Reacted by Snowapril and Hera youknowone commented on Jul 15, 2022 well, working is better than broken. I think we are going on correct way including #3064 youknowone commented on Dec 25, 2025 we now have separated reduce_ex
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