Add rule-empty-line-before rule

[jeddy3]

Closes #2229

I’ll update the rule to use the new empty line utils (to ignore shared-line comments) in v8.

[hudochenkov]

Good job!

With new rule it won't be possible to enforce this style:

a {
    display: block;
    
    span {
    }
    strong {
    }
}
a {
    span {
    }
    strong {
    }
}

There should be no empty lines before a rule, except if it's inside a block and after non-rule. I can enforce this style with:

{
    "rules": {
        "rule-non-nested-empty-line-before": ["never", {
            "ignore": ["after-comment"]
        }],
        "rule-nested-empty-line-before": ["always", {
            "except": ["first-nested", "after-rule"],
            "ignore": ["after-comment"]
        }]
    }
}

How about new option except: ["inside-block-and-after-non-rule"]?

Then I would be able enforce this style with:

{
    "rules": {
        "rule-empty-line-before": ["never", {
            "except": ["inside-block-and-after-non-rule"],
            "ignore": ["after-comment"]
        }]
    }
}

[hudochenkov]

Do you think it's a good idea delete links to docs? These rules still in stylelint, despite the fact they are deprecated. When user will see a deprecation message, she may want to read what this rule for. But it will be very difficult to find.

[jeddy3]

Good point.

Can you create a PR that adds them back in for the other 13 deprecated rules? Please append "(deprecated)." to the end of the description.

[hudochenkov]

Will do today.

[hudochenkov]

Why it's explicitly for a single-line comment?

[jeddy3]

This rule mimics the options from the previous two rules. Only the rule-nested... had the after single line comment exception, as there was a specific request for that functionality.

[jeddy3]

With new rule it won't be possible to enforce this style:

@hudochenkov Thanks for the feedback.

How about new option except: ["inside-block-and-after-non-rule"]?

We don't have the concept of non-things as the recommend approach is to set the primary option to the most common occurrence and then invert it using except options. So, instead of "never" and except: ["after-non-rule"], the recommendation is to use "always" and except: ["after-rule"].

I've added except: ["after-rule"].

I think that covers off a few use-cases. I suggest we roll with what we have and then wait for requests for more idiosyncratic code styles.

[hudochenkov]

Could you add tests for nested rules either, please? New option affects both non-nested and nested rules.

[jeddy3]

Done

[hudochenkov]

except: ["after-rule"] makes sense. Thank you!

[hudochenkov]

Nicely done!

[hudochenkov]

Will do today.

[davidtheclark]

👍 I think the multi-line examples should be improved; otherwise looks good.

[davidtheclark]

I think these are confusing examples. Multi-line rules typically manifest as multiple lines of declarations — that's what people will recognize. Let's do that.

[jeddy3]

Done, or did you mean actually put a declaration inside the block?

[hudochenkov]

@jeddy3 As a user I would have better understanding if there would be declarations.

[jeddy3]

Thing is, "multi-line" doesn't necessarily mean multiple declarations.

This is multi-line:

a {
  color: red;
}

i.e. the rule spans multiple lines.

Perhaps a single declaration is the clearest?

[hudochenkov]

From a user perspective your example with a single declaration isn't always a multi-line rule :) User might assume that this is single-line rule.

In fact you're right, of course.

[davidtheclark]

@jeddy3 You're right: that seems fine to me, too.

[jeddy3]

@davidtheclark I'm around this evening and can finish the release (woohoo!), if you're about to review stylelint/stylelint-config-standard#60 and feedback on the example changes here.

FYI:

• stylelint-config-standard
• stylelint.io
• stylelint-demo

Are all ready-to-go against this branch.

[jeddy3]

Changlog:

• Deprecated: 15 rules (#2197, #2285 & #2309).
  - rule-nested-empty-line-before and rule-non-nested-empty-line-before. Use the new rule-empty-line-before rule instead.