notorious pass by reference vs pass by value biting me in the backside
here. Proceeding in order.
I need to scan a list of strings. If one of the elements matches the
beginning of a search keyword, that element needs to snap to the front
of the list.
I achieved that this way:
for i in range(len(mylist)):
if(mylist[i].startswith(key)):
mylist = [mylist[i]] + mylist[:i] + mylist[i+1:]
Since I need this code in multiple places, I placed it inside a function
def bringOrderStringToFront(mylist, key):
for i in range(len(mylist)):
if(mylist[i].startswith(key)):
mylist = [mylist[i]] + mylist[:i] + mylist[i+1:]
and called it this way:
if orderstring:
bringOrderStringToFront(Tokens, orderstring)
right?
Nope, wrong! contrary to what I thought I had understood about how
parameters are passed in Python, the function is acting on a copy(!) and
my original list is unchanged.
I fixed it this way:
def bringOrderStringToFront(mylist, key):
for i in range(len(mylist)):
if(mylist[i].startswith(key)):
mylist = [mylist[i]] + mylist[:i] + mylist[i+1:]
return(mylist)
and:
if orderstring:
Tokens = bringOrderStringToFront(Tokens, orderstring)
but I'm left with a sour taste of not understanding what I was doing
wrong. Can anyone elaborate? what's the pythonista way to do it right?
Thanks
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