(Mostly) fix format strings for Py 3.6 to % substitutions

fixfmtstr.py

import re

def lines(fname='awssg.py'):
	with open(fname,'r') as fd:
		for line in fd.readlines():
			if "f'" in line:
				yield line

def fmt_str(line):
	ex = r'f\'(.*)\''
	yield from re.finditer(ex, line)

def fix_line(l):
	m, = fmt_str(l)
	a, b, c = l[:m.start()], l[m.start()+2:m.end()-1], l[m.end():]
	return a + fix_fstr(b) + c

def fix_fstr(ts):
	nl = ''
	i = 0
	args = []
	for m in re.finditer(r'{(.*?)}', ts):
		nl = nl + ts[i:m.start()] + '%s'
		i = m.end()
		args.append(m.group()[1:-1])
	nl = nl + ts[i:]
	return '(%r %% (%s))' % (nl, ', '.join(args))

def fix_file(fname):
	new_lines = []
	with open(fname, 'r') as fd:
		for line in fd.readlines():
			if "f'" in line:
				line = fix_line(line)
			new_lines.append(line)
	with open(fname, 'w') as fd:
		for line in new_lines:
			fd.write(line)
	print('%d lines written' % (len(new_lines)))

Oops indented with \ts, oh well..