[Python-Dev] unsubscriptable vs object does not support indexing (original) (raw)

Dino Viehland dinov at microsoft.com
Wed Sep 23 02:23:56 CEST 2009

Is there a reason or a rule by which CPython reports different error message for different failures to subscript?

For example:

set()[2] Traceback (most recent call last): File "", line 1, in TypeError: 'set' object does not support indexing class c(object): pass ... c()[2] Traceback (most recent call last): File "", line 1, in TypeError: 'c' object does not support indexing

But compare this to:

[].append[42] Traceback (most recent call last): File "", line 1, in TypeError: 'builtin_function_or_method' object is unsubscriptable (lambda: 42)[42] Traceback (most recent call last): File "", line 1, in TypeError: 'function' object is unsubscriptable property()[42] Traceback (most recent call last): File "", line 1, in TypeError: 'property' object is unsubscriptable

IronPython had a bug report that we were getting this wrong for set objects and that "does not support indexing" was also a clearer error message. I'm wondering if there's some reason why the different error messages occur which I'm missing. Otherwise I could switch to using the more clear message or start marking types which should report the unsubscriptable error. Does anyone have any insights into this? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20090923/dbb5efab/attachment.htm>

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