One liners

[Roy Smith]

In article <52a287cb$0$30003$c3e8da3$5496439d at news.astraweb.com>,
 Steven D'Aprano <steve+comp.lang.python at pearwood.info> wrote:

> The ternary if is slightly unusual and unfamiliar

It's only unusual an unfamiliar if you're not used to using it :-)  
Coming from a C/C++ background, I always found the lack of a ternary 
expression rather limiting.  There was much rejoicing in these parts 
when it was added to the language relatively recently.  I use them a lot.

On the other hand, I found list comprehensions to be mind-bogglingly 
confusing when I first saw them (read: slightly unusual and unfamiliar).  
It took me a long time to warm up to the concept.  Now I love them.

> As for readability, I accept that ternary if is unusual compared to other 
> languages, but it's still quite readable in small doses. If you start 
> chaining them:
> 
> result = a if condition else b if flag else c if predicate else d 
> 
> you probably shouldn't.

That I agree with (and it's just as true in C as it is in Python).

Just for fun, I took a look through the Songza code base.  66 kloc of 
non-whitespace Python.  I found 192 ternary expressions.  Here's a few 
of the more bizarre ones (none of which I consider remotely readable):

--------------------------------------------------
extracols = sorted(set.union(*(set(t.data.keys()) for t in tracks))) if 
tracks else []
--------------------------------------------------
c2s = compids2songs(set(targets.keys()) | 
set.union(*map(set,targets.itervalues())),self.docmap,self.logger) if 
targets else {}
--------------------------------------------------
code = 2 if (pmp3,paac)==(mmp3,maac) else 3 if any(x is None for x in 
(pmp3,paac,mmp3,maac)) else 4
--------------------------------------------------

Anybody else have some fun ternary abuse examples?