How to match the string in $(....) in python

Question

with open('templates/data.xml', 'r') as s:
    for line in s:
    line = line.rstrip() #removes trailing whitespace and '\n' chars

    if "\\$\\(" not in line:
        if ")" not in line:
                continue

    print(line)

    start = line.index("$(")    
    end = line.index(")")

    print(line[start+2:end])

I need to match the strings which are like $(hello). But now this even matches (hello).

Im really new to python. So what am i doing wrong here ?

Answer 1

Use the following regex:

\$\(([^)]+)\)

It matches $, followed by (, then anything until the last ), and catches the characters between the parenthesis.

Here we did escape the $, ( and ) since when you use a function that accepts a regex (like findall), you don't want $ to be treated as the special character $, but as the literal "$" (same holds for the ( and )). However, note that the inner parenthesis didn't get quoted since you want to capture the text between the outer parenthesis.

Note that you don't need to escape the special characters when you're not using regex.

Answer 2

You can do:

>>> import re
>>> escaper = re.compile(r'\$\((.*?)\)')
>>> escaper.findall("I like to say $(hello)")
['hello']