POV-Ray

The Persistence of Vision Raytracer (POV-Ray).

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Attached to Project: POV-Ray
Opened by Mike H - 2010-06-09
Last edited by Christoph Lipka - 2010-08-29

FS#122 - #ELSEIF statement

Request an #ELSEIF statement in POV SDL.

Closed by  Christoph Lipka
Sunday, 29 August 2010, 20:13 GMT
Reason for closing:  Fixed
Admin
Christoph Lipka commented on Saturday, 19 June 2010, 00:29 GMT

implemented with change #5021

Jim Holsenback commented on Saturday, 19 June 2010, 01:28 GMT

Isn't the current #switch implementation an elseif variant?

Admin
Christoph Lipka commented on Saturday, 19 June 2010, 02:20 GMT

The #switch directive is only designed for situations where all conditions are identity or range comparisons with one common expression; #elseif on the other hand is designed to help with the generic case where the #else branch is comprised of just another #if directive, as in: 

#if ( Foo != Bar )
  // A
#else
  #if ( Fnord = 42 )
    // B
  #else
    #if ( IsFoobar )
      // C
    #else
      // D
    #end
  #end
#end

With #elseif, this can be written much prettier as: 

#if ( Foo != Bar )
  // A
#elseif ( Fnord = 42 )
  // B
#elseif ( IsFoobar )
  // C
#else
  // D
#end

There is also a way to do this with #switch, but I wouldn't consider it very intuitive, and it also comes with some pitfalls.

Mike H commented on Sunday, 20 June 2010, 00:11 GMT

#switch also only compares against a single value. Further, in some languages you are limited to only string and number values (not sure how this applies to POV-Ray since there are no objects in the programming sense...).

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