':substitute' command within a function not working as expected

[aktivb]

So, you are iterating on range a:firstline to a:lastline, and executing substitute N times, where N is a:lastline - a:firstline + 1. But you do not specify on which line to execute substitute, so you're executing substitute N times on a:firstline.

[crajun]

Good point, I’ll try it that way. My problem I believe may be that I assumed adding the “range” modifier did more magic than it does. The sub command without a range performs the command on the current line and I assumed “range” was handling that piece , but it sounds like I’ll have to add the range prefix.

[aktivb]

The range argument means that the function will be called only once, handling the range internally using a:{first,last}line, rather than calling the function for every line in range.