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8133 :: [tables] ref object with "not nil" does not have default value

• aleclarson (orginal) [2021-06-19T18:54:10+02:00] view original

  The following example does not compile.

  • How do I fix it?
  • Why isn't data initialized by default?

  {.experimental: "notnil".}
  
  type FooObj = object
    foo: int
  
  type Foo = ref FooObj not nil
  
  var tbl: Table[string, Foo]
  #    ^ The Table[system.string, Foo not nil] not nil type doesn't have a default value. The following fields must be initialized: data.
  
  tbl["a"] = Foo(foo: 1)
  Run

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• ynfle (orginal) [2021-06-19T22:47:48+02:00] view original

  Try this: https://play.nim-lang.org/#ix=3qub. There are 2 possible solutions in there

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• ElegantBeef (orginal) [2021-06-19T23:18:05+02:00] view original

  Don't use newTable unless you want a ref table, you can just do var tbl = initTable[string, Foo](). I think the reason this is required is the not nil notation does not check compiler magic, and as such it doesnt know that data is actually initialized.

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• xigoi (orginal) [2021-06-19T23:19:37+02:00] view original

  Be aware that tblOption1 is a ref Table, not a Table. The new proc does a heap allocation.

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