Question

I don’t understand the following part of the Python docs:

http://docs.python.org/reference/expressions.html#slicings

Is this referring to list slicing ( x=[1,2,3,4]; x[0:2] )..? Particularly the parts referring to ellipsis..

slice_item       ::=  expression | proper_slice | ellipsis 

The conversion of a slice item that is an expression is that expression. The conversion of an ellipsis slice item is the built-in Ellipsis object.

Answer 1

Defining simple test class that just prints what is being passed:

>>> class TestGetitem(object): ...   def __getitem__(self, item): ...     print type(item), item ...  >>> t = TestGetitem() 

Expression example:

>>> t[1] <type 'int'> 1 >>> t[3-2] <type 'int'> 1 >>> t['test'] <type 'str'> test >>> t[t] <class '__main__.TestGetitem'> <__main__.TestGetitem object at 0xb7e9bc4c> 

Slice example:

>>> t[1:2] <type 'slice'> slice(1, 2, None) >>> t[1:'this':t] <type 'slice'> slice(1, 'this', <__main__.TestGetitem object at 0xb7e9bc4c>) 

Ellipsis example:

>>> t[...] <type 'ellipsis'> Ellipsis 

Tuple with ellipsis and slice:

>>> t[...,1:] <type 'tuple'> (Ellipsis, slice(1, None, None))