Issue 25836: Documentation of MAKE_FUNCTION/MAKE_CLOSURE_EXTENDED_ARG is misleading (original) (raw)

Issue25836

Created on 2015-12-11 04:13 by freakboy3742, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (3)
msg256189 - (view)	Author: Russell Keith-Magee (freakboy3742) *	Date: 2015-12-11 04:13
Refs Issue16554, Issue13026, Issue14349, and probably others. The documentation for the interpretation of the argc argument to MAKE_FUNCTION in Doc/library/dis.rst is incorrect. As of 13 August 2015, the docs say: """ Pushes a new function object on the stack. From bottom to top, the consumed stack must consist of: * ``argc & 0xFF`` default argument objects in positional order * ``(argc >> 8) & 0xFF`` pairs of name and default argument, with the name just below the object on the stack, for keyword-only parameters * ``(argc >> 16) & 0x7FFF`` parameter annotation objects * a tuple listing the parameter names for the annotations (only if there are ony annotation objects) * the code associated with the function (at TOS1) * the :term:`qualified name` of the function (at TOS) """ However, this doesn't capture the fact that: * if there are annotations, the number of default arguments returned by `argc & 0xFF` must be reduced by `(argc >> 16) & 0x7FFF` * The value `(argc >> 16) & 0x7FFF` for the number of annotations *includes* the "extra" entry for the tuple describing which arguments the annotations apply to. This means that `(argc >> 16) & 0x7FFF` will be either 0, or 2+; it can't be 1 (because if you have one annotation, you must also have a tuple describing which arguments is annotated).
msg256632 - (view)	Author: Russell Keith-Magee (freakboy3742) *	Date: 2015-12-18 01:42
It turns out I wasn't completely correct. As per my second point, the interpretation of annotations needs be clarified, but my first point about default_args including the annotation count is incorrect. My error was made because of the documentation for EXTENDED_ARG. The current text implies that you need to combine the argument value of the EXTENDED_ARG opcode with the argument value for the previous opcode. However if you're using dis.Bytecode() to extract bytecodes, that composition is done for you - you can effectively ignore the EXTENDED_ARG opcode.
msg314238 - (view)	Author: Serhiy Storchaka (serhiy.storchaka) *	Date: 2018-03-22 09:19
MAKE_FUNCTION was changed in 3.6, and its documentation was changed accordingly. 3.5 is now in security-only fixes stage.