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Active Forums => QB64 Discussion => Topic started by: stoneskipper on October 02, 2018, 09:53:15 pm

Title: LCAP / UCAP -- Suggested QB64 Commands. Thoughts?
Post by: stoneskipper on October 02, 2018, 09:53:15 pm

Looking for opinions/feedback on the usefulness of the following code implementation -- a shorthand for longer blocks of implicit code, commonly encountered:
__________

LCAP & UCAP

Cap/limit a variable's min/max value. Possibly referencing the current/floating val of another variable, or else fixed with option parameter, eg., "F". Capped variable values are assessed/adjusted only during assignment. Hypothetical examples:

LCAP X (-4.5)               '  IF X < -4.5 then X = -4.5
 X = 2 - 10
  print X
>> -4.5
- - - - - - - - - -

UCAP X (A + 5): LCAP Y (X)      '  IF X > A + 5 then X = [Current Value of A] + 5
 A = 4: X = 10: Y = 4            ' & IF Y < X then Y = [Current Value of X]
  print X; Y
>> 9   9
 A = 3
  print X; Y
>> 9   9
 X = X: Y = -Y               ' X / Y retain value until reassigned/reassessed
 print X; Y
>> 8   8
- - - - - - - - - -

UCAP X (A + 5), F: LCAP Y (X)      '  X-Max locks at 1st assigned value vs. A (unless eg.,  _FREECAP), Y can float
 A = 4: X = 10: Y = 4
  print X; Y
>> 9   9
 A = 3
  print X; Y
>> 9   9
 X = X: Y = -Y
 print X; Y
>> 9   9
- - - - - - - - - -

UCAP X (A + 5): LCAP Y (X), F      '  Y-Min locks at 1st assigned val vs. X, X can float
 A = 4: X = 10: Y = 4
  print X; Y
>> 9   9
 A = 3
  print X; Y
>> 9   9
 X = X: Y = -Y
 print X; Y
>> 8   9

Title: Re: LCAP / UCAP -- Suggested QB64 Commands. Thoughts?
Post by: FellippeHeitor on October 02, 2018, 10:13:13 pm

I don't know how I feel about it.

Title: Re: LCAP / UCAP -- Suggested QB64 Commands. Thoughts?
Post by: stoneskipper on October 03, 2018, 09:16:19 pm

... Any arguments, personal or abstract, either for or against, beyond the ambiguous feeling?

Title: Re: LCAP / UCAP -- Suggested QB64 Commands. Thoughts?
Post by: bplus on October 03, 2018, 09:27:22 pm

This reminds me of two functions max and min that are used say to keep x and y inbounds of screen.

rightSide = 800
x = x + 10
x = min( x, rightSide)  'want x to be always to left of right border
>> x never goes beyond right border

Actually can write those two lines as:
x = min(x+10, rightSide)

Sorry I keep adding stuff:
Modulus is used like this.

Title: Re: LCAP / UCAP -- Suggested QB64 Commands. Thoughts?
Post by: codeguy on October 03, 2018, 10:21:38 pm

I use a similar function, but it wraps to a value between min and Max (inclusive) as part of a HashTable calculation and does not use MOD.

Code: [Select]

Function keepinrange#(x as double, min as double, max as double)
If max > min then
  y# = x
  Do
    If y# < min then
       y# = y# - min + max
    Elseif y# > max then
       y# = y# - max + min
    Else
      keepinrange# = y#
      Exit function
    End if
  Loop
Else
    keepinrange# = min
End if


Title: Re: LCAP / UCAP -- Suggested QB64 Commands. Thoughts?
Post by: FellippeHeitor on October 03, 2018, 10:36:27 pm

We've all had to cap a value either to a lower or upper boundary. A custom function for that is a breeze to write.

What I don't feel strongly about is having a value being constantly monitored and capped in the background by an external force (one that isn't explicitly coded by the user).

Title: Re: LCAP / UCAP -- Suggested QB64 Commands. Thoughts?
Post by: codeguy on October 03, 2018, 10:40:38 pm

I agree with Felipe. Don't add overhead monitoring and capping values to a range. One simple per-need call is all that's necessary and adds zero cpu overhead except when explicitly called.

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