[Python-Dev] repeated keyword arguments

[Scott Dial]

Scott Dial wrote:
> The regression is purely in the way an argument list is reduced to a 
> dictionary.

To further elaborate:

Python 2.4:
 >>> import dis
 >>> dis.dis(compile('f(a=3, b=1, a=4)', '', 'eval'))
Traceback (most recent call last):
   File "<stdin>", line 1, in ?
SyntaxError: duplicate keyword argument

Python 2.5:
 >>> import dis
 >>> dis.dis(compile('f(a=3, b=1, a=4)', '', 'eval'))
   1           0 LOAD_NAME                0 (f)
               3 LOAD_CONST               0 ('a')
               6 LOAD_CONST               1 (3)
               9 LOAD_CONST               2 ('b')
              12 LOAD_CONST               3 (1)
              15 LOAD_CONST               0 ('a')
              18 LOAD_CONST               4 (4)
              21 CALL_FUNCTION          768
              24 RETURN_VALUE

The old compiler checked for this, but the AST-based compiler just 
blindly compiles the entire keyword argument sequence.

-Scott

-- 
Scott Dial
scott at scottdial.com
scodial at cs.indiana.edu