Question

I have this RoR code as follows;

1. error_regex = /\|FileName.exe\|((dlg|frm|cls).*?)/
2. error_regex.match(backtrace)
3. if !error_regex.nil?
4.    file_name = error_regex[1].sub!(/\.zip/, '')
5.    file_name
6. end

So my question is, whats happening on line 3 here.
I have basically zero RoR experience, so looking at this code I read it as
If error_regex.nil is not nil then continue

but whats the ? for
couldn’t I just do

if !error_regex.nil

The regex are all fine, I am just trying to get my head around this syntax.

Answer 1

The question mark is used to indicate that the method, by convention, returns a boolean. Similar examples are include? for Arrays, (returns true if the array has the given element in it), empty? for Strings (returns true if the string == ""), and zero? for Integers (returns true if the int is zero).

So it’s not Rails specific – it’s Ruby-specific.