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a16f126614
refs #23091, especially post merge comments
Unsure if `experimental` and `bind` are the perfect constructs to use
but they seem to get the job done here. Symbol nodes do not get marked
`nfOpenSym` if the `bind` statement is used for their symbol, and
`nfOpenSym` nodes do not get replaced by new local symbols if the
experimental switch is not enabled in the local context (meaning it also
works with `push experimental`). However this incurs a warning as the
fact that the node is marked `nfOpenSym` means we did not `bind` it, so
we might want to do that or turn on the experimental switch if we didn't
intend to bind it.
The experimental switch name is arbitrary and could be changed.
---------
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
(cherry picked from commit 4b1a841707)
51 lines
1.4 KiB
Nim
51 lines
1.4 KiB
Nim
type Xxx = enum
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error
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value
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type
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Result[T, E] = object
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when T is void:
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when E is void:
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oResultPrivate*: bool
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else:
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case oResultPrivate*: bool
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of false:
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eResultPrivate*: E
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of true:
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discard
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else:
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when E is void:
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case oResultPrivate*: bool
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of false:
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discard
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of true:
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vResultPrivate*: T
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else:
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case oResultPrivate*: bool
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of false:
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eResultPrivate*: E
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of true:
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vResultPrivate*: T
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template valueOr[T: not void, E](self: Result[T, E], def: untyped): untyped =
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let s = (self) # TODO avoid copy
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case s.oResultPrivate
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of true:
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s.vResultPrivate
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of false:
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when E isnot void:
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template error: untyped {.used, inject.} = s.eResultPrivate
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def
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proc f(): Result[int, cstring] =
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Result[int, cstring](oResultPrivate: false, eResultPrivate: "f")
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proc g(T: type): string =
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let x = f().valueOr:
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return $error #[tt.Warning
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^ 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]]#
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"ok"
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discard g(int)
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