POV-Ray : Newsgroups : povray.newusers : Ignorance rules! : Re: Ignorance rules! Server Time
24 Jun 2021 07:36:48 EDT (-0400)
  Re: Ignorance rules!  
From: Bald Eagle
Date: 22 Jun 2020 17:05:06
Message: <web.5ef11bf3ea0d75eafb0b41570@news.povray.org>
Cousin Ricky <ric### [at] yahoocom> wrote:
> One just has to keep in mind POV-Ray's scope leakage
> problems[2] when choosing names:
>
>    - Once a macro is defined, its name cannot be reused as a global or
>      local identifier--though it can be reused as a macro formal
>      parameter.
>    - Once a function is defined, its name cannot be reused as a global
>      or local identifier--though it can be reused as a macro formal
>      parameter.
>    - Once *any* identifier is declared, it cannot be reused as a macro
>      name.
>    - Once *any* identifier is declared, it cannot be reused as a
>      function name.
>    - Once *any* identifier is declared, it cannot be reused as a
>      function formal parameter.  (If you were unlucky, math.inc 3.5
>      would bomb out for this very reason.  Precautions were taken
>      starting with math.inc 3.6; for an example, you can take a look
>      at function adj_range2().)

These things are good to know.
Scope can get pretty tricky and anxiety-inducing when I'm using things like
nested loops inside of macros, etc.
I'm never really sure when my identifier is valid/retains its value and when it
gets "released".
One day, when i get other things out of my hair, I'll probably try to write an
example scene that does all sorts of identifier backflips and other other
calisthenics.


> [1] I hadn't yet discovered f_sqr() and sgn() from math.inc,

I'm not sure why things like sgn() aren't in the source code.  It drives me
crazy when certain things I'd consider central to the operation of a lot of code
aren't written in the source code, and need to rely on include files...

And we don't really have very many proper matrix handling macros - which I kind
of found surprising for a 3D graphics package.

Thanks for you summary of the scope issues - these should make their way into
the official documentation.


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