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Object addTrait should require at least one argument.

This reduces confusion about the behavior of "Foo addTrait".
If someone really wants to add nil as a trait to Foo,
it should be done explicitly.

Reviewed by jer.
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1 parent e23b786 commit 615152203980852600cdc96546e221752cf10641 @soc soc committed Feb 27, 2012
Showing with 6 additions and 0 deletions.
  1. +2 −0 libs/iovm/io/
  2. +4 −0 libs/iovm/tests/correctness/
@@ -1,5 +1,7 @@
//doc Object addTrait Takes another object, whose slots will be copied into the receiver. Optionally takes a second argument, a Map object containing string -> string pairs, holding conflicting slot names and names to rename them to. I.e., if you have two objects A and B, both have a slot named foo, you issue A addTrait(B, Map clone atPut("foo", "newFoo")) the value of B foo will be placed in A newFoo.
Object addTrait := method(obj,
+ if(call message arguments size == 0,
+ Exception raise("addTrait requires at least one argument"))
resolutions := call evalArgAt(1)
if(resolutions isNil, resolutions = Map clone)
@@ -21,4 +21,8 @@ TraitsTest := UnitTest clone do(
assertEquals(42, B fooFromA)
assertEquals(23, B foo)
+ testMissingArguments := method(
+ assertRaisesException(A addTrait)
+ )

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