[Python-Dev] list += string??
dave at boost-consulting.com
Thu Aug 26 16:58:26 CEST 2004
Tim Peters <tim.peters at gmail.com> writes:
> [David Abrahams]
>> I just discovered the following behavior:
>> C:\Documents and Settings\dave>python
>> Python 2.3 (#46, Aug 25 2003, 18:37:29) [MSC v.1200 32 bit (Intel)] on win32
>> Type "help", "copyright", "credits" or "license" for more information.
>> >>> prefix = ['foo', 'bar', 'baz']
>> >>> prefix += 'bomb' # meant to write prefix += [ 'bomb' ]
>> >>> prefix
>> ['foo', 'bar', 'baz', 'b', 'o', 'm', 'b']
>> Is it new and/or intentional? I would have expected an error from the
>> +=. I was very surprised when my error "passed silently".
> It was new when the iterator protocol was introduced. It wasn't
> explicitly intended that you get surprises for strings specifically,
> but it was explicitly intended that
> list += whatever
> work like
> and that whatever can be any iterable object.
I figured as much.
> Since strings are iterable objects, it's no more or less surprising
> than that 'for ch in "bomb"' works too <wink>.
I want my ,= operator!
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