[Python-ideas] Showing qualified names when a function call fails

[Chris Barker]

On Tue, Oct 25, 2016 at 6:58 AM, Chris Angelico <rosuav at gmail.com> wrote:

> >     >>> tuple(foo)
> >
> >     TypeError: 'int' object is not iterable
> >
> > No raiser, no value given. It's hard to find out what's the problem is.
> The
> > biggest issue here is that if you have a long line with tuple() in the
> > middle, yuou need to know the problem comes from tuple.
> >
> > Another problem is that many people don't know what iterable means.
> >
> > A better error message would be:
> >
> > TypeError: tuple() only accept iterables (any object you can use a for
> loop
> > on). But it received '1', which is of type <int>.
>
> -1 on this one. It doesn't really add very much - "iterable" is a good
> keyword that anyone can put into a search engine.


yes, that's OK -- and that is the spec of the tuple constructor, yes?


> Adding the repr of
> the object that was passed is nice if it's an integer, but less so if
> you passed in some huge object.
>

I'm not sure you need the repr of the object passed in -- the type is
usually sufficient. (for a TypeError -- for a ValueError, then the value IS
important, and a repr is nice.


> If your lines of code are so complicated that you can't pinpoint the
> cause of the TypeError, the solution is probably to break the line.


yes, but it would be nice not to have to -- maybe I'm just overdoing the
one-liners, but I VERY often have errors liek this on a line, and have to
go in and break the line by hand to find out where the error is actually
coming from.

SyntaxErrors make some effort to indicate WHERE in the line the Error is -
it would be great to get some help like that in these cases. Not sure how
possible it is though.

As I think about it, I tend to get this with indexing error, where a have a
fairly complex expression with multiple objects being indexed, and then a
get an IndexError and have no idea where the problem is.


> >    SyntaxError: bytes can only contain ASCII literal characters.
> >
> > This is not helpful to somebody unaware of the difference between text
> and
> > bytes.
>
> Someone unaware of the difference between text and bytes probably
> isn't messing with code that has b"..." strings in it.


or shouldn't be :-)




-- 

Christopher Barker, Ph.D.
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