`object-curly-newline`: new option request

I’m on eslint v2.13.1.

The multiline: true option is excellent: it lets me require that when newlines exist, every property must be on its own line.

Combining it with minProperties is half useful, however: when it’s set to, say, 3, that means that any objects with 3 or more properties must be split onto multiple lines, which is great! Unfortunately, this also means that objects with less than 3 properties must not be split onto multiple lines.

What I’d like instead is something like { multiline: true, maxPropertiesBeforeForcedNewline: 2 } which says that if there are > 2 properties, the object must be multiline, but if there are <= 2, the object may be single or multi, provided that it’s consistent with the multiline: true option.

[mysticatea]

Thank you for this issue.

Maybe similar to #6369. I think this is reasonable.

What do you think either option?

/*eslint object-curly-newline: [error, {either: true}]*/

// ✘ BAD
var obj = {a: 1
}
var obj = {
    a: 1}

// ✔ GOOD
var obj = {a: 1}
var obj = {
    a: 1
}

• "always" - requires line breaks always.
• "never" - disallows line breaks.
• {multiline: true} (default) - requires line breaks if there are line breaks inside properties or between properties. Otherwise, disallows line breaks.
• {minProperties: <integer>} - requires line breaks if the number of properties is more than the given integer. Otherwise, disallows line breaks.
• {either: true} - requires line breaks (of both braces) if either brace has a line break.

multiline and minProperties and either can be combined.

• {multiline: true, minProperties: <integer>, either: true} - requires line breaks if there are line breaks inside properties or between properties, or if the number of properties is more than the given integer, or if either brace has a line break. Otherwise, disallows line breaks.

If either option is enabled, this rule never disallows line breaks.

[ljharb]

What rule do you want to change? object-curly-newline

Does this change cause the rule to produce more or fewer warnings? Fewer.

How will the change be implemented? (New option, new default behavior, etc.)? New option: consistent. When true, it requires that either both curly braces, or neither, directly enclose newlines.

Please provide some example code that this change will affect:

cat temp

var one = { a: 1 };

var two = { a: 1, b: 2 };

var three = { a: 1, b: 2, c: 3 };

var oneM = {
  a: 1
};

var twoM = {
  a: 1,
  b: 2
};

var threeM = {
  a: 1,
  b: 2,
  c: 3
};

var wat = { a: 1
};

var wat2 = {
a: 1 };

var wat3 = { a: 1,
  b: 2,
  c: 3 };

What does the rule currently do for this code?

cat temp | ./node_modules/.bin/eslint --stdin --no-eslintrc --rule='object-curly-newline:[2, {"minProperties": 3, "multiline": true}]'

<text>
   5:13  error  Expected a line break after this opening brace   object-curly-newline
   5:32  error  Expected a line break before this closing brace  object-curly-newline
   7:12  error  Unexpected line break after this opening brace   object-curly-newline
   9:1   error  Unexpected line break before this closing brace  object-curly-newline
  23:1   error  Unexpected line break before this closing brace  object-curly-newline
  25:12  error  Unexpected line break after this opening brace   object-curly-newline
  28:12  error  Expected a line break after this opening brace   object-curly-newline
  30:8   error  Expected a line break before this closing brace  object-curly-newline

✖ 8 problems (8 errors, 0 warnings)

What will the rule do after it’s changed?

cat temp | ./node_modules/.bin/eslint --stdin --no-eslintrc --rule='object-curly-newline:[2, {"minProperties": 3, "multiline": true, "consistent": true}]'

<text>
   5:13  error  Expected a line break after this opening brace   object-curly-newline
   5:32  error  Expected a line break before this closing brace  object-curly-newline
  23:1   error  Unexpected line break before this closing brace  object-curly-newline
  25:12  error  Unexpected line break after this opening brace   object-curly-newline
  28:12  error  Expected a line break after this opening brace   object-curly-newline
  30:8   error  Expected a line break before this closing brace  object-curly-newline

✖ 6 problems (6 errors, 0 warnings)

Perhaps a better alternative is actually fixing minProperties to mean “min properties to force multiline”, instead of meaning “number of properties that determines whether it must be multiline or single-line”, but that gets into the require/disallow complexity.