Terry J. Reedy <[email protected]> added the comment:
Stephen is right; this sort of guess-the-bug heuristic is out of scope for the
CPython interpreter. I believe you grossly under estimate the difficulty of
such a this. Consider that idea rejected.
What *is* disconcerting is the exact form of the error message for this
particular code pattern:
Traceback (most recent call last):
File "<pyshell#0>", line 3, in <module>
(4, 5, 6)
TypeError: 'tuple' object is not callable
Uh... There was no attempt to call the tuple (4,5,6), which was misinterpreted
as a () call operator with 3 args. What might be a reasonable request is to
print a size-limited representation of the object that is not callable but was
attempted to be called. Truncated representations would be generally useful for
traceback messages. I believe we already have them for unittest error messages.
A useful document for someone (or some people) to write would be 'How to
interpret exception messages'. That could start with a catalog of messages and
possible causes. 'type' would be used to stand for any specific type.
The section on TypeErrors would have an heading
'type' object is not callable
followed by an explanation
There are two general reasons for this message. The first is that you
intentionally write "expression(args)" with the intent that expression evaluate
to a callable, but it does not. The second is that you accidentally omit a
comma in a sequence and write "expression (tuple_members)". Note that the error
is triggered by the "(args)" call operator and its line is the one printed. So
if "expression" is on the preceeding line, it will not appear in the traceback.
This can happen with either type of error.
In the meanwhile, the above is a start for a faq entry.
----------
nosy: +terry.reedy
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<http://bugs.python.org/issue15248>
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