[Python-3000] removing destructuring del

[Neal Norwitz]

On Fri, Feb 22, 2008 at 7:44 AM, Guido van Rossum <guido at python.org> wrote:

[... del (tuple, of, variables), etc deleted]

>
>  >  I also think
>  >
>  >    del a,
>  >
>  >  should not be legal ("SyntaxError: trailing comma not allowed without
>  >  surrounding parentheses"?), but that's getting into my own personal
>  >  preferences.
>
>  These all make sense to me, but at the same time it seems such a minor
>  issue that I'm not sure we should bother. It would probably end up
>  being more custom syntax -- right now it just uses exprlist in the
>  grammar and is limited to assignment targets by the compiler.

What bothers me more is assert of a tuple.  It does the wrong thing
from what newbies expect.  pychecker warns about this, but the version
of pylint in use at Google doesn't warn about this.  I wonder if we
should add a warning?

The code I recently saw was:
  assert (something_short,
               'Some long assertion string that needs its own line')

The original code that pylint warned about was:
  assert something_short, \
               'Some long assertion string that needs its own line'

Index: Python/compile.c
===================================================================
--- Python/compile.c    (revision 61058)
+++ Python/compile.c    (working copy)
@@ -2056,6 +2056,9 @@
                if (assertion_error == NULL)
                        return 0;
        }
+       if (s->v.Assert.test->kind == Tuple_kind) {
+               printf("got a tuple\n");
+       }
        VISIT(c, expr, s->v.Assert.test);
        end = compiler_new_block(c);
        if (end == NULL)

Seems to do the trick.  Maybe this should be turned into a real patch
with using PyErr_Warn()?

n