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Diffstat (limited to 'src/library/scala/reflect/api/Trees.scala')
| -rw-r--r-- | src/library/scala/reflect/api/Trees.scala | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/src/library/scala/reflect/api/Trees.scala b/src/library/scala/reflect/api/Trees.scala index 8c13ae5da7..de01c0b862 100644 --- a/src/library/scala/reflect/api/Trees.scala +++ b/src/library/scala/reflect/api/Trees.scala @@ -94,8 +94,22 @@ trait Trees /*extends reflect.generic.Trees*/ { self: Universe => */ def setType(tp: Type): this.type = { rawtpe = tp; this } - /** Like `setType`, but if this is a previously empty TypeTree - * that fact is remembered so that resetType will snap back. + /** Like `setType`, but if this is a previously empty TypeTree that + * fact is remembered so that resetAllAttrs will snap back. + * + * @PP: Attempting to elaborate on the above, I find: If defineType + * is called on a TypeTree whose type field is null or NoType, + * this is recorded as "wasEmpty = true". That value is used in + * ResetAttrsTraverser, which nulls out the type field of TypeTrees + * for which wasEmpty is true, leaving the others alone. + * + * resetAllAttrs is used in situations where some speculative + * typing of a tree takes place, fails, and the tree needs to be + * returned to its former state to try again. So according to me: + * using `defineType` instead of `setType` is how you communicate + * that the type being set does not depend on any previous state, + * and therefore should be abandoned if the current line of type + * inquiry doesn't work out. */ def defineType(tp: Type): this.type = setType(tp) |