How to handle Maths

1. We decided on strict maths going forward but there is general unease about forcing () around every calculation
2. I don’t think we want to change things massively or go back to the drawing board

See #1872

Possibility to add another case for calc which like font, with strict mode off, essentially turns strict mode on for a rule ? Too many exceptions in the future?

@seven-phases-max : Well, there’re a lot of other possibilities, e.g. ./ or require parens for division (e.g. 1/2->1/2 but (1/2)->0.5) etc… Also, the “special cases” (e.g. properties where x/y can appear as shorthand) are not so rare (starting at padding/margin and ending with background/border-radius and eventually there can be more) so we just can’t hardcode them all like it’s done for font (and because of that I think that the current font “workaround” is just a temporary and quite dirty kludge that ideally should be removed too).

[thany]

@matthew-dean Incidentally, this is how Sass resolves the problem, illustrated by this example:

That’s a brilliant solution without resorting to a different operator. If the expression is possibly valid CSS, leave it.

Personally, I think making developers try to remember in which cases math will occur based on the existence of magic expressions is kind of crazy-making

Disagree. It’s a simple set of rules, no different from any other sets of (crazy or not) rules you need to remember.

There are a few edge-cases where maths does occur without meaning to, but then you’ll just apply parentheses and you’re done.

[matthew-dean]

To simplify / restate the proposal - Math changes would be as follows

1. Addition and subtraction would only be calculated on like units. e.g. 1px + 2px = 3px, 1px + 1vh = 1px + 1vh
2. Division and multiplication would only be calculated with unit-less divisors/multipliers. e.g. 10px/2 = 5px, 10px/5px = 10px/5px
3. Value ratios without units would be treated similarly to # 2. e.g. 1/3 = 1/3
4. For simplification, expressions with partially invalid sub-expressions can be treated as an invalid math expression and output as-is. e.g. 1px + 2vh / 2 = 1px + 2vh / 2

This proposal solves the following (from this thread):

• font: 10px/5px and similar (ratio) syntax (no calculation)
• calc(100vh - 30px) (no calculation)
• lost-column: 1/3 and similar custom ratio syntax (no calculation)

At the same time, these changes would preserve 99% of typical Less math usage. As well, the existing unit() and convert() functions allow users to cast values into compatible units for math.