Augmented Assignment, the Python Way (huge)

[Yhg1s]

BPO	400699
Nosy	@gvanrossum, @Yhg1s
Files	None: None

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/Yhg1s'
closed_at = <Date 2000-08-24.20:12:16.000>
created_at = <Date 2000-07-01.00:42:41.000>
labels = ['interpreter-core']
title = 'Augmented Assignment, the Python Way (huge)'
updated_at = <Date 2000-08-24.20:12:16.000>
user = 'https://github.com/Yhg1s'

bugs.python.org fields:

activity = <Date 2000-08-24.20:12:16.000>
actor = 'twouters'
assignee = 'twouters'
closed = True
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2000-07-01.00:42:41.000>
creator = 'twouters'
dependencies = []
files = ['2509']
hgrepos = []
issue_num = 400699
keywords = ['patch']
message_count = 10.0
messages = ['32981', '32982', '32983', '32984', '32985', '32986', '32987', '32988', '32989', '32990']
nosy_count = 3.0
nosy_names = ['gvanrossum', 'jhylton', 'twouters']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue400699'
versions = []

[Yhg1s]

No description provided.

[Yhg1s]

This patch adds augmented assignment (+=, **=, etc) to Python, in a manner which seems consistent with Guido and Tim's wishes (for as far as I know them.)

Guido has already stated this patch will not make it to Python 2.0, so the first to read this should probably set the state to 'postponed'. I'll try and keep this patch up to date none the less, for peer (or rather parent ;) reviewal.

The patch adds everything in one smack: Syntax, a new type of bytecode (2-argument), 9 new bytecodes, 13 new API calls, 11 new PyNumber_Methods members, 2 new PySequence_Methods members, and support for the new functionality in builtin types and supplied Python classes. Oh, and a test suite.

None the less, it isn't that intrusive a patch, and the simplicity of the implementation still boggles me. For more information, see http://www.xs4all.nl/~thomas/python/
Comments greatly appreciated! Contact me on thomas@xs4all.net (I'm not on python-dev)

[gvanrossum]

Cool! We'll look at this after 2.0 is released...

[jhylton]

This patch needs to be postponed until the PEP is written.

[gvanrossum]

Not ready to be checked in, but Thomas is working on it!
This will be in 2.0 after all...

[Yhg1s]

New version of the patch, that eliminates the need for 2-argument opcodes and the GETSET_* opcodes. Instead, INPLACE_* opcodes are used, that mirror the BINARY_* opcodes, and two new 'utility' opcodes: ROT_FOUR and DUP_TOPX (duplicates the top <x> items on the stack.)

The PEP documenting this implementation will follow soon.

[gvanrossum]

BDFL pronouncement: please use __iadd__, __imul__ etc.

[Yhg1s]

Up to date version that incorporates the BDFL-Pronouncement to use __iadd__ rather than __add_ab__. Also made PyNumber_InPlacePower() a three-argument function (since normal Power() is one, and we can't change this functions' prototype later, if we would want to.) The three argument InPlacePower() does the normal batch of coercions, so it's not terribly likely to remain an 'in-place' operation :-S

I'm working on docs, but on my laptop, not incorporated in this patch. Also, the testcase needs to be expanded a bit, and probably incorporated with the test_class testcase I added last week.

[gvanrossum]

Accepted. Please check it in. Then work on the docs.

Please send us the docs even if you don't get to finish them!!!

[Yhg1s]

This patch is being checked in right now. However, the patch as found here is not the same as the one being checked in: Guido suggested a better way to do the PyNumber_InPlace*() API functions, which also removes the biggest remaining issue from the PEP, and the patch going in implements that suggestion.