The command 'once' is not doing what is expected

• 05/23/2018 at 10:17 AM #71154
  Vagus_Lux

  Please try out following lines

  Defparam DRAWONLASTBARONLY = TRUE M1 = Barindex once M2 = M1 DRAWTEXT("M1=#M1#", BarIndex[1], 0.1) DRAWTEXT("M2=#M2#", BarIndex[1], -0.1) Return

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  Defparam DRAWONLASTBARONLY = TRUE M1 = Barindex once M2 = M1 DRAWTEXT("M1=#M1#", BarIndex[1], 0.1) DRAWTEXT("M2=#M2#", BarIndex[1], -0.1) Return

  I would expect that M2 is getting the value of M1 but the value stays zero!

  

  Vagus_Lux

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  05/23/2018 at 10:26 AM #71158
  robertogozzi

  It DOES do what it is expected from it!

  That’s because ONCE is executed only ONCE; when you launch that code BARINDEX=0, so will be M1 and, finally… M2, which will NEVER be executed again (while M1 continues growing).

  

  robertogozzi

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  05/23/2018 at 12:39 PM #71168
  Vagus_Lux

  Thanks for your prompt answer. Could you please help me to understand the following:

  M1 = barindex if barindex >2 then once M2 = M1 endif return M2

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  M1 = barindex if barindex >2 then once M2 = M1 endif return M2

  It still returns zero!

  

  Vagus_Lux

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  05/23/2018 at 1:14 PM #71175
  Vonasi

  Not sure why it does not pick up the value but you do not really need the once. This code will fix the value as you want it. The Once is not necessary if you use an =

  if barindex = 3 then M2 = Barindex endif return M2 as "M2", barindex as "BarIndex"

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  if barindex = 3 then M2 = Barindex endif   return M2 as "M2", barindex as "BarIndex"

  p.s. – it is preferred if you use the ‘Insert PRT Code’ button when posting code in the forums. I’ve tidied up your posts for you!

  1 user thanked author for this post.

  Nicolas

  

  Vonasi

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  05/23/2018 at 2:13 PM #71182
  robertogozzi

  ONCE is read by the system ONCE at launch time, so your code could be written as

  M1 = barindex if barindex >2 then //once M2 = M1 endif return M2

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  M1 = barindex if barindex >2 then    //once M2 = M1 endif return M2

  When BarIndex is ZERO the IF…ENDIF block will be skipped, later, when executed, line 3 will be skipped because of the ONCE keyword.

   

  

  robertogozzi

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  05/23/2018 at 2:15 PM #71183
  Vagus_Lux

  Thanks for your alternative code. You are right there are often many ways around. My sample code had to discover the missfunction of the command ‘once’ just in principle and my hope is to get it working in future. It was thought as a request to the programmer. I obvioused that the missfunction is limited to barindex but it works fine with other values.

  

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  05/23/2018 at 2:17 PM #71185
  Vonasi

  robertogozzi wrote:

  ONCE is read by the system ONCE at launch time

  Which so obviously why it does not work at BarIndex 3! I must be tired….

  

  Vonasi

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  05/23/2018 at 2:27 PM #71187
  Vagus_Lux

  Do I get it right that ONCE is executed just one time in the very first loop of a program? So that it is not useful to use ONCE it in a later loop independent on its position? Thanks for your support to getting a better understanding.

   

  

  Vagus_Lux

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  05/23/2018 at 2:31 PM #71188
  robertogozzi

  ONCE is used to initialize a variable (PRT doeas not tell between variables and constants), as soon as the code is launched, after that it will simply be ignored, no matter where you write it.

   

   

  

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  05/23/2018 at 2:47 PM #71190
  Vagus_Lux

  So it is no missfunction it was just my misunderstanding of the comand ONCE.
  Thank so much for your patience!

  

  Vagus_Lux

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