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7060 :: Is this possible? Default iterator fields.

• bartimus (orginal) [2020-11-09T19:24:56+01:00] view original

  So, I used nim back before v1, so it has been awhile. I recently started looking at it again now that it has matured a lot.

  running through my default language learning program, I ran into this question:

  Background I have two objects:

  1. person object
  2. family object

  
  type
      Person* = object
          name: string
          age: int
          sex: Sex
  
  type
      Family* = object
          members: seq[Person]
          name: string
  Run

  the family object contains a sequence of persons, these are in a separate file, and members is not exposed. I would like to be able to run the following code in another file:

  
  for person in family:
      echo(person.name)
  
  Run

  I understand i can just make the members field public, but I would like to know if there is another way of doing this. Like overwriting the 'in' operator and exposing that or is there a way to set the Family object to use the member field as the iterator? I wrote this to add a member to the family, so it looks like the flexibility is there, just don't know how to implement it.

  
  proc `+`*(f: var Family, p: Person) =
      f.members.add(p)
  Run

  Thanks.

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• bartimus (orginal) [2020-11-09T19:44:15+01:00] view original

  nvm - i wasn't using the iterator items*

  
  iterator items*(f: Family): Person =
      var i = 0
      while i < f.members.len:
          yield f.members[i]
          inc i
  Run

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• xigoi (orginal) [2020-11-09T20:42:53+01:00] view original

  You can simplify this:

  iterator items*(f: Family): Person =
      for member in f.members:
          yield member
  Run

  Unfortunately, Nim doesn't have an equivalent of Python's yield from and the aliasing PR didn't get accepted, so this is the best you can do.

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• bartimus (orginal) [2020-11-10T15:48:59+01:00] view original

  oh sweet! even easier. Much appreciated

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