Message2309

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user_id=61408

if we eagerly coerce then (at least for instances), for
example changing half_cmp to test:

        if (o1.__class__ != o2.__class__ || o1 instanceof
PyInstance
            || o2 instanceof PyInstance) {

the output becomes:
log: [] coerce((),C()): (<__main__.C instance 1>,
<__main__.C instance 2>)
log: ['C_coerce', 'D_eq'] cmp(C(),C()): 0
log: ['D_eq'] cmp(C(),D()): 0
log: ['D_eq'] cmp(D(),C()): 0
log: ['D_eq'] cmp(D(),D()): 0
log: ['C_coerce', 'D_eq'] C()==C(): 1
log: ['D_eq'] C()==D(): 1
log: ['D_eq'] D()==C(): 1
log: ['D_eq'] D()==D(): 1

[yep, also builtin coerce need fixing]

notice the 0 because 
  return o1._cmp(o2); 
tries __eq__.

I'm tempted to go with something like this [not tested]:

        int half = this.__cmp__(other)
        if (half != -2)
        {
            return half;
        }
        if (!(this instanceof PyInstance) {
           half = other.__cmp__(this);
          if (half != -2)
          {
              return -half;
          }
        }

pushing the coercion logic down the PyObject subclasses like
we do for all the other bin ops, and having
PyInstance.__cmp__ doing everything necessary for that case
like instance_compare
in CPython does. I may try this on the newstyle branch.

Thanks.