What do list comprehensions do that generator expressions don't?

[Mark English]

> Date: Mon, 25 Apr 2005 08:51:17 -0500
> From: Mike Meyer <mwm at mired.org>

> Which means that the real rule should be always use generator
expressions,
> unless you *know* the expression will always fit in memory.

> Which leads to the obvious question of why the exception.
<code>
>>> l = [(1, 2), ('a', 'b'), (3, 2), (23, 32)]
>>> l
[(1, 2), ('a', 'b'), (3, 2), (23, 32)]
</code>
This screen dump of the object is quite useful to me.

<code>
>>> r = reversed(l)
>>> r
<listreverseiterator object at 0x009D2B90>
</code>
This screen dump of the object is less useful to me.

>From a pure programming point of view it's not a sufficient reason to
keep list comprehensions, especially as the interpreter shell could be
massaged into giving more output, but right here right now it's a lot
easier to read the former than the latter IMHO.

(That is assuming I'm right in assuming functions like "reversed" are
generator expressions).

Mark



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