Merge pull request #9806 from guggero/formatting-list-initializations

docs: document formatting for slice definitions

docs/development_guidelines.md

@@ -230,9 +230,13 @@ value, err := bar(
 )
 ```
 
-As long as the visual symmetry of the opening and closing parentheses is
+As long as the visual symmetry of the opening and closing parentheses (or curly
-preserved, arguments that would otherwise introduce a new level of indentation
+braces) is preserved, arguments that would otherwise introduce a new level of
-are allowed to be written in a more compact form.
+indentation are allowed to be written in a more compact form.
+Visual symmetry here means that when two or more opening parentheses or curly
+braces are on the same line, then they must also be closed on the same line.
+And the closing line needs to have the same indentation level as the opening
+line.
 
 Example with inline struct creation:
 
@@ -254,6 +258,13 @@ Example with inline struct creation:
 	})
 ```
 
+**WRONG**
+```go
+	response, err := node.AddInvoice(ctx, &lnrpc.Invoice{
+		Memo:      "invoice",
+		ValueMsat: int64(oneUnitMilliSat - 1)})
+```
+
 Example with nested function call:
 
 **ACCEPTABLE**:
@@ -448,6 +459,65 @@ func foo(a, b, c,
 }
 ```
 
+### Inline slice definitions
+
+In Go a list of slices can be initialized with values directly, using curly
+braces. Whenever possible, the more verbose/indented style should be used for
+better readability and easier git diff handling. Because that results in more
+levels of code indentation, the more compact version is allowed in situations
+where the remaining space would otherwise be too restricted, resulting in too
+long lines (or excessive use of the `// nolint: ll` directive).
+
+**ACCEPTABLE**
+```go
+	testCases := []testCase{{
+		name: "spend exactly all",
+		coins: []wallet.Coin{{
+			TxOut: wire.TxOut{
+				PkScript: p2wkhScript,
+				Value:    1 * btcutil.SatoshiPerBitcoin,
+			},
+		}},
+	}, {
+		name: "spend more",
+		coins: []wallet.Coin{{
+			TxOut: wire.TxOut{
+				PkScript: p2wkhScript,
+				Value:    1 * btcutil.SatoshiPerBitcoin,
+			},
+		}},
+	}}
+```
+
+**PREFERRED**
+```go
+	coin := btcutil.SatoshiPerBitcoin
+	testCases := []testCase{
+		{
+			name: "spend exactly all",
+			coins: []wallet.Coin{
+				{
+					TxOut: wire.TxOut{
+						PkScript: p2wkhScript,
+						Value:    1 * coin,
+					},
+				},
+			},
+		},
+		{
+			name: "spend more",
+			coins: []wallet.Coin{
+				{
+					TxOut: wire.TxOut{
+						PkScript: p2wkhScript,
+						Value:    1 * coin,
+					},
+				},
+			},
+		},
+	}
+```
+
 ## Recommended settings for your editor
 
 To make it easier to follow the rules outlined above, we recommend setting up