(Code contributed by Jiwon Seo.)
The documentation portion of the patch is being re-worked and will be
checked-in soon. Likewise, PEP 289 will be updated to reflect Guido's
rationale for the design decisions on binding behavior (as described in
in his patch comments and in discussions on python-dev).
The test file, test_genexps.py, is written in doctest format and is
meant to exercise all aspects of the the patch. Further additions are
welcome from everyone. Please stress test this new feature as much as
possible before the alpha release.
The old syntax suggested that a trailing comma was OK inside backticks,
but in fact (due to ideosyncrasies of pgen) it was not. Fix the grammar
to avoid the ambiguity. Fred: you may want to update the refman.
"for <var> in <testlist> may no longer be a single test followed by
a comma. This solves SF bug #431886. Note that if the testlist
contains more than one test, a trailing comma is still allowed, for
maximum backward compatibility; but this example is not:
[(x, y) for x in range(10), for y in range(10)]
^
The fix involved creating a new nonterminal 'testlist_safe' whose
definition doesn't allow the trailing comma if there's only one test:
testlist_safe: test [(',' test)+ [',']]
This introduces:
- A new operator // that means floor division (the kind of division
where 1/2 is 0).
- The "future division" statement ("from __future__ import division)
which changes the meaning of the / operator to implement "true
division" (where 1/2 is 0.5).
- New overloadable operators __truediv__ and __floordiv__.
- New slots in the PyNumberMethods struct for true and floor division,
new abstract APIs for them, new opcodes, and so on.
I emphasize that without the future division statement, the semantics
of / will remain unchanged until Python 3.0.
Not yet implemented are warnings (default off) when / is used with int
or long arguments.
This has been on display since 7/31 as SF patch #443474.
Flames to /dev/null.
eval_code2(): Implement new bytecodes PRINT_ITEM_TO and
PRINT_NEWLINE_TO, as per accepted SF patch #100970.
Also update graminit.c based on related Grammar/Grammar changes.
name as n'. By doing some twists and turns, "as" is not a reserved word.
There is a slight change in semantics for 'from module import name' (it will
now honour the 'global' keyword) but only in cases that are explicitly
undocumented.
executive summary:
Instead of typing 'apply(f, args, kwargs)' you can type 'f(*arg, **kwargs)'.
Some file-by-file details follow.
Grammar/Grammar:
simplify varargslist, replacing '*' '*' with '**'
add * & ** options to arglist
Include/opcode.h & Lib/dis.py:
define three new opcodes
CALL_FUNCTION_VAR
CALL_FUNCTION_KW
CALL_FUNCTION_VAR_KW
Python/ceval.c:
extend TypeError "keyword parameter redefined" message to include
the name of the offending keyword
reindent CALL_FUNCTION using four spaces
add handling of sequences and dictionaries using extend calls
fix function import_from to use PyErr_Format
* funcobject.c (func_repr): don't call getstringvalue(None) for anonymous
functions.
* bltinmodule.c: removed lambda (which is now a built-in function);
removed implied lambda for string arg to filter/map/reduce.
* Grammar, graminit.[ch], compile.[ch]: replaced lambda as built-in
function by lambda as grammar entity: instead of "lambda('x: x+1')" you
write "lambda x: x+1".
* Xtmodule.c (checkargdict): return 0, not NULL, for error.
* PROTO.h, mymalloc.h: added #ifdefs for TURBOC and GNUC.
* allobjects.h: added #include "rangeobject.h"
* Grammar: added lambda_input; relaxed syntax for exec.
* bltinmodule.c: added bagof, map, reduce, lambda, xrange.
* tupleobject.[ch]: added resizetuple().
* rangeobject.[ch]: new object type to speed up range operations (not
convinced this is needed!!!)
* Grammar: add exec statement; allow testlist in expr statement.
* ceval.c, compile.c, opcode.h: support exec statement;
avoid optimizing locals when it is used
* fileobject.{c,h}: add getfilename() internal function.
Added $(SYSDEF) to its build rule in Makefile.
* cgensupport.[ch], modsupport.[ch]: removed some old stuff. Also
changed files that still used it... And made several things static
that weren't but should have been... And other minor cleanups...
* listobject.[ch]: add external interfaces {set,get}listslice
* socketmodule.c: fix bugs in new send() argument parsing.
* sunaudiodevmodule.c: added flush() and close().
(1) dictionaries/mappings now have attributes values() and items() as
well as keys(); at the C level, use the new function mappinggetnext()
to iterate over a dictionary.
(2) "class C(): ..." is now illegal; you must write "class C: ...".
(3) Class objects now know their own name (finally!); and minor
improvements to the way how classes, functions and methods are
represented as strings.
(4) Added an "access" statement and semantics. (This is still
experimental -- as long as you don't use the keyword 'access' nothing
should be changed.)
Raymond Hettinger
Martin v. Löwis
Guido van Rossum
Tim Peters
Thomas Wouters
Skip Montanaro
Barry Warsaw
Jeremy Hylton