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type Xxx = enum
error
value
type
Result[T, E] = object
when T is void:
when E is void:
oResultPrivate*: bool
else:
case oResultPrivate*: bool
of false:
eResultPrivate*: E
of true:
discard
else:
when E is void:
case oResultPrivate*: bool
of false:
discard
of true:
vResultPrivate*: T
else:
case oResultPrivate*: bool
of false:
eResultPrivate*: E
of true:
vResultPrivate*: T
template valueOr[T: not void, E](self: Result[T, E], def: untyped): untyped =
let s = (self) # TODO avoid copy
case s.oResultPrivate
of true:
s.vResultPrivate
of false:
when E isnot void:
template error: untyped {.used, inject.} = s.eResultPrivate
def
proc f(): Result[int, cstring] =
Result[int, cstring](oResultPrivate: false, eResultPrivate: "f")
proc g(T: type): string =
let x = f().valueOr:
return $error #[tt.Warning
^ a new symbol 'error' has been injected during instantiation of g, however 'error' [enumField declared in tmacroinjectedsymwarning.nim(2, 3)] captured at the proc declaration will be used instead; either enable --experimental:genericsOpenSym to use the injected symbol or `bind` this captured symbol explicitly [GenericsIgnoredInjection]]#
"ok"
discard g(int)
|