Michael <mi************ @gmail.comwrote :
Thus, whenever I need to pass information to a function, I use default
arguments now. Is there any reason not to do this other than the fact
that it is a bit more typing?
You're giving your functions a signature that's different from the one
you expect it to be called with, and so making it impossible for the
Python runtime to diagnose certain errors on the caller's part.
For example, consider:
def makecounter_goo d():
counts = {}
def count(item):
result = counts[item] = 1 + counts.get(item , 0)
return result
return count
c = makecounter_goo d()
for i in range(3): print c(23)
def makecounter_hmm m():
counts = {}
def count(item, counts=counts):
result = counts[item] = 1 + counts.get(item , 0)
return result
return count
cc = makecounter_hmm m()
for i in range(3): print cc(23)
print cc(23, {})
print c(23, {})
Counters made by makecounter_goo d take exactly one argument, and
properly raise exceptions if incorrectly called with two; counters made
by makecounter_hmm m take two arguments (of which one is optional), and
thus hide some runtime call errors.
From "import this":
"""
Errors should never pass silently.
Unless explicitly silenced.
"""
The miniscule "optimizati on" of giving a function an argument it's not
_meant_ to have somewhat breaks this part of the "Zen of Python", and
thus I consider it somewhat unclean.
Alex
