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The following commit(s) were added to refs/heads/asf-site by this push:
new 6c80ad6 compound assignment operator overloading proposal (minor
tweaks)
6c80ad6 is described below
commit 6c80ad6a42f04f635474b5a2ae6b6a434e597c13
Author: Paul King <[email protected]>
AuthorDate: Sun Apr 12 18:53:52 2026 +1000
compound assignment operator overloading proposal (minor tweaks)
---
site/src/site/wiki/GEP-15.adoc | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/site/src/site/wiki/GEP-15.adoc b/site/src/site/wiki/GEP-15.adoc
index f03355d..3ccfb9a 100644
--- a/site/src/site/wiki/GEP-15.adoc
+++ b/site/src/site/wiki/GEP-15.adoc
@@ -95,10 +95,14 @@ When the compiler encounters `x += y`:
4. If `x` is `final` and no `plusAssign` exists, report a compile error
(in `@CompileStatic` mode).
-When both `plusAssign` and `plus` exist on the same type, `plusAssign`
-takes precedence. This is the pragmatic choice for Groovy since it lacks
-Kotlin's `val`/`var` distinction. If a class author defined `plusAssign`,
-they intended it to be used for `+=`.
+When both `plusAssign` and `plus` exist on the same
+type, `plusAssign` takes precedence.
+Languages like Kotlin apply an ambiguity resolution rule
+where the selection between `plusAssign` and `plus`
+depends on the mutability of the receiver (`val` vs `var`).
+This is not typical for Groovy method selection.
+If a class author defined `plusAssign`,
+they intend it to be used for `+=`.
=== Design considerations
@@ -155,7 +159,7 @@ bus.listeners <<= "listener1" // calls
listeners.leftShiftAssign("listener1")
In `@CompileStatic` mode, the type checker resolves `plusAssign` at
compile time using `findMethod()`. If found, it records the target method
on the expression via node metadata and the bytecode generator emits a
-direct method call -- no dup, no store-back.
+direct method call with no reassignment to the variable.
If not found, the existing desugaring to `x = x.plus(y)` applies.
@@ -163,7 +167,7 @@ If not found, the existing desugaring to `x = x.plus(y)`
applies.
In dynamic Groovy, the runtime checks for `plusAssign` via the Meta-Object
Protocol (MOP). If `respondsTo(target, "plusAssign", arg)` succeeds, it is
-called. Otherwise, the fallback to `plus` + reassignment applies.
+called. Otherwise, the fallback to `plus` with reassignment applies.
This requires a new runtime helper method (e.g., in `ScriptBytecodeAdapter`)
that encapsulates the try-assign-then-fallback logic.
