I recently saw a reference to "exotic signatures" and the fact they had been deprecated in 2.6 (and removed in 3.0). The example given is
def exotic_signature((x, y)=(1,2)): return x+y
What makes this an "exotic" signature?
views:
251answers:
3
+5
A:
What's exotic is that x and y represent a single function argument that is unpacked into two values... x and y. It's equivalent to:
def func(n):
x, y = n
...
Both functions require a single argument (list or tuple) that contains two elements.
FogleBird
2009-05-19 17:31:20
I'm pretty sure that's the exact example that Hank Gay saw "exotic signatures" used. A single example is not a very good demonstration of what a term encompasses.
Daniel Lew
2009-05-19 17:34:02
Yes, I did Google. That was the reference. It's not clear to me what makes that signature "exotic".
Hank Gay
2009-05-19 17:34:30
I thought the example made it straight-forward. (I had never heard the term myself) I edited my answer with more detail.
FogleBird
2009-05-19 17:40:19
Thanks. Swapped my vote.
Hank Gay
2009-05-19 17:41:17
That's interesting^^ What Python calls exotic is done in functional programming languages all day long (passing + decomposing patterns and tupels in arguments). These do even use currying to make their function signatures more confusing ;-)
Dario
2009-05-19 17:44:33
@Dario: currying is available in Python too, see functools.partial at http://docs.python.org/library/functools.html#functools.partial . And btw, a person calling them "exotic" does not mean that Python documentation calls them "exotic".
ΤΖΩΤΖΙΟΥ
2009-05-21 08:01:33
+5
A:
More information about tuple parameter unpacking (and why it is removed) here: http://www.python.org/dev/peps/pep-3113/
truppo
2009-05-19 17:41:57
+1
A:
Here's a slightly more complex example. Let's say you're doing some kind of graphics programming and you've got a list of points.
points = [(1,2), (-3,1), (4,-2), (-1,5), (3,3)]
and you want to know how far away they are from the origin. You might define a function like this:
def magnitude((x,y)):
return (x**2 + y**2)**0.5
and then you can find the distances of your points from (0,0) as:
map(magnitude, points)
...well, at least, you could in python 2.x :-)
John Fouhy
2009-05-19 22:11:11