Op 12-03-14 10:51, Ian Kelly schreef: > On Wed, Mar 12, 2014 at 3:39 AM, Antoon Pardon > <antoon.par...@rece.vub.ac.be> wrote: >> The documentation is wrong at that point as the following code illustrates. > Either way it still has to do a getitem and a setitem, but if you have > a more nested structure then the extra getitems are not repeated. For > example, using your logdict class:
Sure, but the documentation doesn't say for sufficiently nested structures some evaluations are not repeated. Take the following example. | tab['key'] = [1] | tab['key'] += [2] Now let us rewrite that second statment in two different ways. | tab['key'] = tab['key'] + [2] or | tmp = tab['key'] | tmp += [2] Now which of these two rewritings is closer to the augmented concatenation? A natural reading of the documentation would conclude the second one, because in that case we only need to evaluate tab['key'] once as righthand sided. However it turns out the augmented concantenation is closer to the first rewriting here, evaluating tab['key'] twice once a lefthand sided and once as right hand sided, which IMO will surprise people that rely on the documentation. -- Antoon Pardon -- https://mail.python.org/mailman/listinfo/python-list
