Well, I think it’s interesting anyway..

So today I was trying to express the idea “do something to all these files, unless the filename matches the list of things we don’t care about”. I have to do a BUNCH of find-and-replace kinda stuff in the next week on a couple thousand webpages, so my plan is to write a little script to make sure I don’t miss anything. Sometimes the script will turn up a false positive that I know I want to ignore..

EDIT – The following snippet doesn’t do quite what I thought it did.. more later..

There are at least three distinct and reasonable ways to do this in Python:

# skip if name matches any of these
ignore = ["thing1", "thing2"]
 
# Iterate over the strings, see if a substring matches
# This is reasonably clear, but it seems long and requires a flag
for filepath in dirwalk(path):
    found = False
    for item in ignore:
        if filepath.find(item) > 0:
            found = True
            break
    if found:
        continue
    # do stuff..
 
# The next two ways build a list of matches
# If there are any matches then skip this file
 
# This is a more functional style
for filepath in dirwalk(path):
    if filter(lambda item: filepath.find(item) != -1, ignore):
        continue
    # do stuff..
 
# Another way to do the same thing
for filepath in dirwalk(path):
    if [item for item in ignore if filepath.find(item) != -1]:
        continue
    # do stuff..

Interestingly, the last two use the same number of characters. I’m not sure which I prefer. While I suspect the final one would be considered the most Pythonic, I do have a soft spot for lambda. Eh, maybe someday when I’m not lazy I will see which is the fastest.. though that doesn’t really matter for my purposes.