Make "def width" a private API; expose isWidthKnown instead (#257)

* Make "def width" a private API; expose isWidthKnown instead

Resolves #256.

Since width was used to determine whether getWidth would succeed, I added

    def isWidthKnown: Boolean

but another option would be to expose something like

    def widthOption: Option[Int]

...thoughts?

* Document getWidth/isWidthKnown

* Add widthOption for more idiomatic Scala manipulation of widths

1 files changed, 3 insertions, 2 deletions

diff --git a/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala b/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
index f2774a8d..15643ac8 100644
--- a/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
+++ b/chiselFrontend/src/main/scala/chisel3/core/Aggregate.scala
@@ -16,7 +16,7 @@ import chisel3.internal.sourceinfo.{SourceInfo, DeprecatedSourceInfo, VecTransfo
   */
 sealed abstract class Aggregate(dirArg: Direction) extends Data(dirArg) {
   private[core] def cloneTypeWidth(width: Width): this.type = cloneType
-  def width: Width = flatten.map(_.width).reduce(_ + _)
+  private[core] def width: Width = flatten.map(_.width).reduce(_ + _)
 }
 
 object Vec {
@@ -373,5 +373,6 @@ class Bundle extends Aggregate(NO_DIR) {
 }
 
 private[core] object Bundle {
-  val keywords = List("flip", "asInput", "asOutput", "cloneType", "toBits")
+  val keywords = List("flip", "asInput", "asOutput", "cloneType", "toBits",
+                      "widthOption")
 }