diff options
| -rw-r--r-- | lib/system.nim | 33 |
1 files changed, 25 insertions, 8 deletions
diff --git a/lib/system.nim b/lib/system.nim index d036e8428..371611f70 100644 --- a/lib/system.nim +++ b/lib/system.nim @@ -904,14 +904,31 @@ template disarm*(x: typed) = ## experimental API! x = nil -proc `of`*[T, S](x: typedesc[T], y: typedesc[S]): bool {.magic: "Of", noSideEffect.} -proc `of`*[T, S](x: T, y: typedesc[S]): bool {.magic: "Of", noSideEffect.} -proc `of`*[T, S](x: T, y: S): bool {.magic: "Of", noSideEffect.} - ## Checks if `x` has a type of `y`. - ## - ## .. code-block:: Nim - ## assert(FloatingPointDefect of Exception) - ## assert(DivByZeroDefect of Exception) +proc `of`*[T, S](x: T, y: typedesc[S]): bool {.magic: "Of", noSideEffect.} = + ## Checks if `x` is an instance of `y`. + runnableExamples: + type + Base = ref object of RootObj + Sub1 = ref object of Base + Sub2 = ref object of Base + Unrelated = ref object + + var base: Base = Sub1() # downcast + doAssert base of Base # generates `CondTrue` (statically true) + doAssert base of Sub1 + doAssert base isnot Sub1 + doAssert not (base of Sub2) + + base = Sub2() # re-assign + doAssert base of Sub2 + doAssert Sub2(base) != nil # upcast + doAssertRaises(ObjectConversionDefect): discard Sub1(base) + + var sub1 = Sub1() + doAssert sub1 of Base + doAssert sub1.Base of Sub1 + + doAssert not compiles(base of Unrelated) proc cmp*[T](x, y: T): int = ## Generic compare proc. |