[Python-ideas] String interpolation again.

Masklinn masklinn at masklinn.net
Fri Jul 23 16:14:59 CEST 2010

On 2010-07-23, at 16:09 , Mike Meyer wrote:
>>> In python, that would be making
>>> str.__add__ (and friends) do the conversion.
>> You'd run into the issues of writing `a + "foo"` with `a` defining a custom `__add__`, which would not perform string concatenation, as per Python's operator resolution order.
> That's what the "and friends" is for. str.__radd__ is one of the
> friends. If the type of a refused to do the add, then str.__radd__
> would get it, and could do the conversion and concatenation.
> Of course, if the type of a did the add in some way *other* than via
> the conversion and concatenation, then that's what would happen. Which
> is one of the reasons this type of implicit conversion isn't right for
> Python.

Right. Because otherwise it should not be very hard (which doesn't mean it would be smart) to remove the type error from str.__add__ and str.__radd__ and just str() the argument if it isn't already a string.

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