[chaley]

Originally Posted by DrChiper

The reason I didn't use intermediate vars is because I noticed that the formatter stops processing/evaluating in case of a nil situation, so this seems to be fastest way to process. But as always, correct me if I'm wrong

This is called "shortcutting". If the formatter can determine that a "then" or "else" clause cannot be evaluated then it skips it. The same thing happens with "and" and "or" expressions. For example, given the expression

'1' || print('foo')

will never print 'foo' because the result of the || is true no matter what the right-hand side does. On the other hand

'1' && print('foo')

will always print 'foo' because both the left-hand and the right-hand must be true for the expression to be true.

program:
	if (field('title')!=transliterate(field('title')))
	then
		if (field('#subtitle')!=transliterate(field('#subtitle')))
		then
			'true1, true2'
		else
			'true1'
		fi
	else
		if (field('#subtitle')!=transliterate(field('#subtitle')))
		then
			'true2'
		else
			'false'
		fi
	fi

It returns true1 for title, true2 for subtitle, or false when neither contains non-ASCII chars.

FWIW and perhaps doing premature optimization: this will be a bit faster because a) local variables are faster than field lookups, and b) switch_if is faster than a series of ifs.

program:
# These two lines depend on evaluation being left to right so the
# variable is set before use.
	title_neq = (t = $title) != transliterate(t);
	authors_neq = (a = $authors) != transliterate(a);

# This code works because given two booleans the "truth table" has four entries.
# The order of evaluation is important. As it is we can avoid extra tests because
# if the first test isn't true then one or both of title_neq and authors_neq 
# must be false. That is why the second and third line don't need to check the
# other variable. The switch_if function does shortcutting.

	switch_if(
		title_neq && authors_neq, 'true1, true2',
		title_neq, 'true1',
		authors_neq, 'true2',
		'false')

The switch_if's arguments can be reordered if one pathway, probably resulting in 'false', is the most common. For example:

program:
	title_neq = (t = $title) != transliterate(t);
	authors_neq = (a = $authors) != transliterate(a);

	switch_if(
# True if both are false
		!(title_neq || authors_neq), 'false',
# True if both are true
		title_neq && authors_neq, 'true1, true2',
# Here, one but not both of title_neq and authors_neq is true.
		title_neq, 'true1',
# title_neq was false so authors_neq must be true.
		'true2')