Better implicit array typing

[ventor3000]

Feature request.

The following code, which implicitly tells Nimrod that vars test and test2 are TAnimalArray:s does not work. Implicit casting of the elements in array to TAnimal should be done.

type
TAnimal=object
PAnimal=ref TObject

TDog=object of TAnimal
PDog=ref TDog

TCat=object of TAnimal
PCat=ref TCat

TAnimalArray=array[0..2,PAnimal]

proc newDog():PDog = new(result)

proc newCat():PCat = new(result)

proc test(a:openarray[PAnimal])=
echo("dummy")

test(newDog(),newCat()) #does not work

var myarray:TAnimalArray=[newDog(),newCat(),newDog()] #does not work

var myarray2:TAnimalArray=[newDog(),newDog(),newDog()] #does not work either

[AdrianV]

+1
It is annoying to cast back to PAnimal every time

[reactormonk]

Nicely formatted:

type
  TAnimal=object {.inheritable.}
  PAnimal=ref TObject

  TDog=object of TAnimal
  PDog=ref TDog

  TCat=object of TAnimal
  PCat=ref TCat

  TAnimalArray=array[0..2,PAnimal]

proc newDog():PDog = new(result)
proc newCat():PCat = new(result)
proc test(a:openarray[PAnimal])=
  echo("dummy")

test(newDog(),newCat()) #does not work
var myarray:TAnimalArray=[newDog(),newCat(),newDog()] #does not work
var myarray2:TAnimalArray=[newDog(),newDog(),newDog()] #does not work either

Yep, implement covariance :-P