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3598 :: Delaying macro expansion

• lotzz (orginal) [2018-03-02T22:40:22+01:00] view original

  So I am making just a small compile time RNG and having a few problems

  macro getRNGF*():float =
    let fh = high(uint32)
    let fr = getRNG()
    return fr.float / fh.float
  Run

  the getRNG proc is another macro that affects some static variables declared earlier, but the problem is that nim expands the macro and gives me a static value that doesn't change with each call.

  I will include the getRNG proc and the variables it affects

  static:
    var mz:uint32 = 36969
    var mw:uint32 = 18000
  
  macro getRNG*():uint32=
    mz =  (36969u32 * mz and high(uint32) + (mz shr 32))
    mw = (18000u32 * mw and high(uint32) + (mw shr 32))
    if mw == 0: mw = 18000
    if mz == 0: mz = 36969
    return (mz shl 16) + mw
  Run

  so my question is if there is anyway to delay macro expansion or some work around to make getRNG's return value not static

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• LeuGim (orginal) [2018-03-02T23:22:21+01:00] view original

  Make getRNG a template? (then you need to delete the return)

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• StasB (orginal) [2018-03-03T07:56:39+01:00] view original

  It looks like you want getRNG to be a compile-time function, so you should use the {.compileTime.} pragma. However, I'm not sure why you'd want a compile-time-only RNG implementation. You could (and should) implement it normally and instantiate it at compile time.

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• mratsim (orginal) [2018-03-03T12:00:48+01:00] view original

  You might want to check this compile-time string obfuscation thread.

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