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5954 :: Can't pass varargs to echo

• DeletedUser (orginal) [2020-02-20T07:51:25+01:00] view original

  I can't tell if this is a bug or if there is a way to change this so it works.

  echo @["a", "b", "c"] # expected, prints @["a", "b", "c"]
  echo(varargs[string](@["a", "b", "c"])) # prints ["a", "b", "c"]
  Run

  This also doesn't cut it:

  proc a(x: varargs[string, `$`]) = echo x
  
  a "a", "b", "c" # prints ["a", "b", "c"]
  Run

  Is this a limitation of the varargs[string, `$`] type? I saw there was a PR that fixed overloading for these types but I don't think I saw anything mentioned about passing varargs between each other. Is there an issue open for this on the Nim github?

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• gemath (orginal) [2020-02-20T11:54:17+01:00] view original

  Since echo takes a varargs[typed] parameter and these are the only exception to the "take a varargs parameter which already is an openarray as the list of args itself" rule, I don't see how to do this. A single parameter passed to echo will always be interpreted as the first of the varargs, not as the list of varargs. Btw, if varargs serves just as an annotation to proc params, a conversion like varargs[T](x) shouldn't even be allowed.

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• Araq (orginal) [2020-02-20T15:41:36+01:00] view original

  Like this:

  import macros
  
  template a(x: varargs[typed, `$`]) = unpackVarargs(echo, x)
  
  a "a", "b", "c"
  Run

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