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1136 :: Update a seq value in place

• kuba (orginal) [2015-04-16T00:07:37+02:00] view original

  Hi there,

  I'd like to update a particular entry in a sequence which is stored as a value of a table, but get the following error:

  "Error: for a 'var' type a variable needs to be passed"
  Run

  Can somebody please explain what the error message stands for?

  Thank you.

  import Tables
  var aaa = initTable[int,seq[int]]()
  var bbb : seq[int] = @[0,1,2,3,4]
  aaa[1]=bbb
  aaa[1].add(5)          #) Error: for a 'var' type a variable needs to be passed
  Run

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• Renesac (orginal) [2015-04-16T00:18:54+02:00] view original

  You need to use aaa.mget(1) to get a mutable parameter for add(). Add is defined as something like "proc add(a: var seq[T], b: T)". Notice the "var" that requires a reference to the value so it can be updated in place.

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• def (orginal) [2015-04-16T00:38:23+02:00] view original

  There is a PR that overloads [] with var parameter, but it breaks much existing code because of a change in semantics, so I'm not sure what to do here: https://github.com/Araq/Nim/pull/2435

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• kuba (orginal) [2015-04-16T01:07:08+02:00] view original

  Cheers that's very valuable.

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