On 10/10/2013 06:41 PM, Terry Reedy wrote:
On 10/10/2013 9:33 AM, Ethan Furman wrote:
On 10/10/2013 12:43 AM, Terry Reedy wrote:
On 10/10/2013 2:45 AM, Chris Angelico wrote:
first_element = some_list[0] # Oops, may crash
some_list[0:1] always works, and sometimes is usable, but you still
cannot index the slice.
Not if some_list is None, False, or another non-indexable type.
Did you really not understand that some_list is intended to be a list? Just
like my_string, for instance, would be a
string? Chris's statement further specifies some_list as a list that is
expected to not be empty, but might be -- so one
has to guard against the possibility.
I understood it just fine. I'm also aware that at some point, in some program,
it will be None (and it won't be a bug ;).
The trick of slicing instead of indexing in this context is not obvious to
everyone learning Python. Most other
languages only have indexing. I learned the trick years ago when someone posted
it on this list.
It's a good trick, I use it myself.
--
~Ethan~
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