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Add optional recursive arg to distinctBase (v2) (#18659)

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* Add optional recursive arg to distinctBase
* Add docs and examples

Co-authored-by: ALANVF <alan.invents@gmail.com>
This commit is contained in:
Timothee Cour 2021-08-08 23:51:39 -07:00 • committed by GitHub
commit 8ce782d463
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4 changed files with 18 additions and 10 deletions
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17
lib/pure/typetraits.nim
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@ -110,25 +110,32 @@ template pointerBase*[T](_: typedesc[ptr T | ref T]): typedesc =
assert (var s = "abc"; s[0].addr).typeof.pointerBase is char
T
proc distinctBase*(T: typedesc): typedesc {.magic: "TypeTrait".} =
proc distinctBase*(T: typedesc, recursive: static bool = true): typedesc {.magic: "TypeTrait".} =
## Returns the base type for distinct types, or the type itself otherwise.
## If `recursive` is false, only the immediate distinct base will be returned.
##
## **See also:**
## * `distinctBase template <#distinctBase.t,T>`_
## * `distinctBase template <#distinctBase.t,T,static[bool]>`_
runnableExamples:
type MyInt = distinct int
type MyOtherInt = distinct MyInt
doAssert distinctBase(MyInt) is int
doAssert distinctBase(MyOtherInt) is int
doAssert distinctBase(MyOtherInt, false) is MyInt
doAssert distinctBase(int) is int
since (1, 1):
template distinctBase*[T](a: T): untyped =
## Overload of `distinctBase <#distinctBase,typedesc>`_ for values.
template distinctBase*[T](a: T, recursive: static bool = true): untyped =
## Overload of `distinctBase <#distinctBase,typedesc,static[bool]>`_ for values.
runnableExamples:
type MyInt = distinct int
type MyOtherInt = distinct MyInt
doAssert 12.MyInt.distinctBase == 12
doAssert 12.MyOtherInt.distinctBase == 12
doAssert 12.MyOtherInt.distinctBase(false) is MyInt
doAssert 12.distinctBase == 12
when T is distinct:
distinctBase(typeof(a))(a)
distinctBase(typeof(a), recursive)(a)
else: # avoids hint ConvFromXtoItselfNotNeeded
a