POV-Ray : Newsgroups : povray.advanced-users : Undefined variables Server Time: 17 Dec 2018 00:35:05 GMT
  Undefined variables (Message 1 to 6 of 6)  
From: Mike Horvath
Subject: Undefined variables
Date: 5 Feb 2018 22:46:55
Message: <5a78dedf$1@news.povray.org>
I am trying to create a macro:

   #macro BlurredReflection(InPigment, InFinish, InNormal)
     ...
   #end

But I don't want to *always* pass a value to the macro. Is there a way 
to pass a "null" or "nil" value to the macro, and then check for it 
using a conditional statement?

Thanks.

Mike


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From: Alain
Subject: Re: Undefined variables
Date: 5 Feb 2018 22:58:31
Message: <5a78e197$1@news.povray.org>
Le 18-02-05 à 17:47, Mike Horvath a écrit :
> I am trying to create a macro:
> 
>    #macro BlurredReflection(InPigment, InFinish, InNormal)
>      ...
>    #end
> 
> But I don't want to *always* pass a value to the macro. Is there a way 
> to pass a "null" or "nil" value to the macro, and then check for it 
> using a conditional statement?
> 
> Thanks.
> 
> Mike

Not any that I'm aware of.
What you can do is define the macro with only a single, or no, parameter 
and use some global variable and #if statements to assign defaut values 
it any variable is not already defined.


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From: Bald Eagle
Subject: Re: Undefined variables
Date: 5 Feb 2018 23:10:00
Message: <web.5a78e3f58fda426b5cafe28e0@news.povray.org>
Mike Horvath <mik### [at] gmailcom> wrote:

> But I don't want to *always* pass a value to the macro. Is there a way
> to pass a "null" or "nil" value to the macro, and then check for it
> using a conditional statement?

I know what you mean.
I just came up with this idea 5 sec ago:

What if you "always" pass a vector to the macro - one that is reset to default
"null" values, and then you can re-#declare the vector before  calling the macro
with the vector as an argument.

That way the vector need not always have the same number of components, but it's
always ONE vector.


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From: dick balaska
Subject: Re: Undefined variables
Date: 6 Feb 2018 01:46:40
Message: <5a790900$1@news.povray.org>
On 02/05/2018 05:47 PM, Mike Horvath wrote:
> I am trying to create a macro:
> 
>    #macro BlurredReflection(InPigment, InFinish, InNormal)
>      ...
>    #end
> 
> But I don't want to *always* pass a value to the macro. Is there a way 
> to pass a "null" or "nil" value to the macro, and then check for it 
> using a conditional statement?
> 
> Thanks.
> 
> Mike

There are optional parameters, which may help you out.
http://news.povray.org/povray.beta-test/thread/%3Cweb.58d3f1da55c5eb5fc437ac910%40news.povray.org%3E/

I had a similar need, but I ended up not using optionals, because the 
caller still needs to be aware of the missing parameters via comma 
count; i.e. BlurredReflection(Red,,)

I ended up just creating a mostly duplicate, different named macro with 
the optional parameter.
#macro BlurredReflection(InPigment, Infinish) #end
#macro BlurredReflectionWithNormal(InPigment, InFinish, InNormal) #end

-- 
dik
Rendered 920576 of 921600 pixels (99%)


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From: clipka
Subject: Re: Undefined variables
Date: 6 Feb 2018 13:10:18
Message: <5a79a93a$1@news.povray.org>
Am 05.02.2018 um 23:47 schrieb Mike Horvath:
> I am trying to create a macro:
> 
>   #macro BlurredReflection(InPigment, InFinish, InNormal)
>     ...
>   #end
> 
> But I don't want to *always* pass a value to the macro. Is there a way
> to pass a "null" or "nil" value to the macro, and then check for it
> using a conditional statement?

In the new versions, you can use e.g.

    #macro Fnord(A, optional B, C)
      #ifdef(local.B)
        #debug "Got a value for B.\n"
      #else
        #debug "B was left empty.\n"
      #endif
    #end

    Fnord(A,,C)


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From: Mike Horvath
Subject: Re: Undefined variables
Date: 6 Feb 2018 13:16:54
Message: <5a79aac6$1@news.povray.org>
On 2/6/2018 8:10 AM, clipka wrote:
> Am 05.02.2018 um 23:47 schrieb Mike Horvath:
>> I am trying to create a macro:
>>
>>    #macro BlurredReflection(InPigment, InFinish, InNormal)
>>      ...
>>    #end
>>
>> But I don't want to *always* pass a value to the macro. Is there a way
>> to pass a "null" or "nil" value to the macro, and then check for it
>> using a conditional statement?
> 
> In the new versions, you can use e.g.
> 
>      #macro Fnord(A, optional B, C)
>        #ifdef(local.B)
>          #debug "Got a value for B.\n"
>        #else
>          #debug "B was left empty.\n"
>        #endif
>      #end
> 
>      Fnord(A,,C)
> 

Interesting, thanks.


Mike


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