Question

I’m just learning python, and seem to be making a trivial mistake. With this code, the use of the constructor to Patterns gets and error.

” cit_ref = Patterns( patstring, 3)
TypeError: this constructor takes no arguments”

import re

class Patterns:
    """A simple struct to hold our regex """
def __init__(self, pat, bodynumArg=2):
    self.pat = pat
    self.bodynum = bodynumArg
    self.reg = re.compile(self.pat, re.M+re.S)

patstring = r'<((us-)?references-cited)>(.*?)</\1>'
cit_ref = Patterns( patstring, 3)

Answer 1

You just need to indent your __init__ function so that it is under class Patterns. Like this:

import re

class Patterns:
    """A simple struct to hold our regex """
    def __init__(self, pat, bodynumArg=2):
        self.pat = pat
        self.bodynum = bodynumArg
        self.reg = re.compile(self.pat, re.M+re.S)

patstring = r'<((us-)?references-cited)>(.*?)</\1>'
cit_ref = Patterns( patstring, 3)

In Python, indents do basically the same thing that brackets/braces do in other languages- they delimit code, so you have to be careful with your indentation.