Nested assignments

[MichaReiser]

Rome's formatter breaks nested assignments onto a new line compared to Prettier that only prints the right-hand side expression on a new line. Playground

Input

// Fits
bifornCringerMoshedPerplex = bifornCringerMoshedPerplexSawder = arrayO = "test"

// Exceeding:
// One assignment
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.arrayOfNumber.m= "test"

// Two assignments
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.arrayOfNumber = ab = "test"

// More than two assignments and exceeding: Each assignment on their own line
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.array = p = ab = "tes"


bifornCringerMoshedPerplex = bifornCringerMoshedPerplexSawder = arrayOfNumb = a = "test"

Prettier

// Fits
bifornCringerMoshedPerplex = bifornCringerMoshedPerplexSawder = arrayO = "test";

// Exceeding:
// One assignment
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.arrayOfNumber.m =
	"test";

// Two assignments
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.arrayOfNumber = ab =
	"test";

// More than two assignments and exceeding: Each assignment on their own line
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.array =
	p =
	ab =
		"tes";

bifornCringerMoshedPerplex =
	bifornCringerMoshedPerplexSawder =
	arrayOfNumb =
	a =
		"test";

Rome

// Fits
bifornCringerMoshedPerplex = bifornCringerMoshedPerplexSawder = arrayO = "test";

// Exceeding:
// One assignment
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.arrayOfNumber.m =
	"test";

// Two assignments
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.arrayOfNumber =
	ab = "test";

// More than two assignments and exceeding: Each assignment on their own line
bifornCringerMoshedPerplex.bifornCringerMoshedPerplexSawder.array =
	p = ab = "tes";

bifornCringerMoshedPerplex =
	bifornCringerMoshedPerplexSawder = arrayOfNumb = a = "test";

Expected

Rome to match Prettier's output.

I'm not entirely sure if I figured out Prettier's heuristic. It could make sense to study prettier's source code before tackling this issue to confirm. But my understanding is that Prettier:

• Breaks between the assignment operator and the right-hand side expression
• Tries to fit up to two assignments on the same line (except if all of them fit).
• The right-hand side is indented one level deeper than the last assignment expression.
• 3+ assignments and exceeding line width: Each assignment on its own line.

[ematipico]

3+ assignments and exceeding line width: Each assignment on its own line.

And different indentation too 🤔

[MichaReiser]

3+ assignments and exceeding line width: Each assignment on its own line.

And different indentation too thinking

All assignment targets have the same indention (except the first one). The right hand side is indented one level deeper.

[ematipico]

I see two level of indentation. Is it a github rendering issue? It's the assigner that gets one more level of indentation.

[MichaReiser]

• .array: First assignment: No indention
• p & ab: Indented one level: These are all other assignment targets
• "test": The value that gets assigned to the assignment targets. Indented one level deeper.

[ematipico]

This requires understanding Prettier's heuristic.

[ematipico]

I will work on this one