Improved alignParameters handling should be opt-in

[jkinkead]

alignParameters handling was expanded in the daniel-trinh fork to include aligning equals signs and default values.

This should possibly be hidden behind an option per #142 .

[jkinkead]

Should this be milestone 1.0, @sschaef / @fommil ? It's an improvement to an existing opt-in feature, but I notice that @jrudolph disabled alignParameters in akka/akka#19936 , probably for this reason.

[jkinkead]

To visualize what I'm talking about, here's an example from akka:

diff --git a/akka-actor/src/main/scala/akka/routing/ConsistentHashing.scala b/akka-actor/src/main/scala/akka/routing/ConsistentHashing.scala
index 1139fc1..e0ba2b1 100644
--- a/akka-actor/src/main/scala/akka/routing/ConsistentHashing.scala
+++ b/akka-actor/src/main/scala/akka/routing/ConsistentHashing.scala
@@ -135,9 +135,9 @@ object ConsistentHashingRoutingLogic {
  */
 @SerialVersionUID(1L)
 final case class ConsistentHashingRoutingLogic(
-  system: ActorSystem,
-  virtualNodesFactor: Int = 0,
-  hashMapping: ConsistentHashingRouter.ConsistentHashMapping = ConsistentHashingRouter.emptyConsistentHashMapping)
+  system:             ActorSystem,
+  virtualNodesFactor: Int                                           = 0,
+  hashMapping:        ConsistentHashingRouter.ConsistentHashMapping = ConsistentHashingRouter.emptyConsistentHashMapping)
   extends RoutingLogic {

   import ConsistentHashingRouter._

Note that the types are aligned as are the default values. This is a new addition to the alignParameters setting - previously, it left-justified all arguments, but left the types & defaults alone.

[fommil]

I really like alignment but haven't used it yet.

[jkinkead]

It's more that you can no longer opt-in to formatting like:

// Int is not aligned with String.
def foo(arg1: Int,
        arg2HasALongName: String): Unit

This is the kind of alignment that v0.1.4 does. Akka disabled alignParameters in the PR I referenced, likely because of this issue.

[jkinkead]

Attached is the full Akka diff with all of the new settings from PR #205 . Note that virtually all of these are either arrow renaming changes or the new align parameters setting. FYI @jrudolph if you're interested in comparing with your PR.

akkadiff.txt

[fommil]

😄 wow, we're actually getting near 1.0

[jrudolph]

I tried your branch with .setPreference(FirstParameterOnNewline, Preserve) but it helps only a little because of these kind of changes:

   def validate[T1, T2](value1: RequestVal[T1],
-                       value2: RequestVal[T2],
-                       check: Function2[T1, T2, JBoolean],
-                       errorMsg: String,
-                       innerRoute: Route, moreInnerRoutes: Route*): Route =
+    value2: RequestVal[T2],
+    check: Function2[T1, T2, JBoolean],
+    errorMsg: String,
+    innerRoute: Route, moreInnerRoutes: Route*): Route =

So, the first line is now preserved but the indentation of the others still changes.

[jkinkead]

@jrudolph - It looks like you left the .setPreference(AlignParameters, false) change in. Try setting that back to true. :)

[jrudolph]

Setting it to true does more than we need:

-  def validate[T1, T2](value1: RequestVal[T1],
-                       value2: RequestVal[T2],
-                       check: Function2[T1, T2, JBoolean],
-                       errorMsg: String,
+  def validate[T1, T2](value1:     RequestVal[T1],
+                       value2:     RequestVal[T2],
+                       check:      Function2[T1, T2, JBoolean],
+                       errorMsg:   String,

[jkinkead]

Precisely. That's what this bug intends to address: The additional alignment of the types & default values in method signatures should be behind a preference, instead of the default behavior of alignParameters.

So, it sounds like this should be milestone 1.0 - @fommil / @sschaef ? I'd tag it myself, but I don't have permissions. :)

[fommil]

we should probably get you added

[jkinkead]

FYI https://github.com/jkinkead/scalariform/tree/align_parameter_types_tmp has a fix. It's very simple, but it's dependent on #205 .

[jrudolph]

@jkinkead thanks, makes sense. If I get to it I'll try your branch.

[jrudolph]

Cool, your new switch works nicely. What's now left over for Akka is

• RARROW
• implicit parameter list formatting (you seem to have a suggestion in implicit argument lists #180)
• it seems to delete lines from block comments, e.g. here https://github.com/akka/akka/pull/19936/files#diff-a09ffa60a39c454ac5f877fda4826a03L21

[jkinkead]

Awesome, that list aligns with my observations as well. :)

• RARROW is tracked in rewriteArrowSymbols shouldn't reformat -> #209 . I'd like some confirmation that people are OK just removing the formatting, instead of hiding it behind a flag (it's dangerous).
• Implicit auto-formatting I can move to a flag.
• Third issue is a regression, fixed in Fix comment formatter to retain blank lines in multiline comments. #208 .