The following code generates this error:

Write(FileHandle <----ERROR
Parse Error: Expected 2 parameters but only 0 found.

#macro Write (File, Doodle)
  #write (File, Doodle)
#end

#fopen FileHandle "c:\\1.txt" write
Write(FileHandle,1)
#fclose FileHandle

While the following code generates this error:

Write(1, FileHandle <----ERROR
Parse Error: Expected 2 parameters but only 1 found.

#macro Write (Doodle, File)
  #write (File, Doodle)
#end

#fopen FileHandle "c:\\1.txt" write
Write(1, FileHandle)
#fclose FileHandle

My question is: can I pass file handles as parameters to macros, and
if yes, how?


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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Peter Popov wrote:
> 
> [...]
> 
> #fopen FileHandle "c:\\1.txt" write
> Write(1, FileHandle)
> #fclose FileHandle
> 
> My question is: can I pass file handles as parameters to macros, and
> if yes, how?
> 

I recently experienced the same problem and i think you can't.  File
handles are different from other identifiers. 

Christoph

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On Tue, 22 Apr 2003 10:55:51 +0200, Christoph Hormann
<chr### [at] gmxde> wrote:

>I recently experienced the same problem and i think you can't.  File
>handles are different from other identifiers. 

Then why can I #undef, #ifdef and #ifndef them? I mean, sure they are
not normal identifiers, you can't assign to them etc. but the fact
that you can't pass them to macros looks to me like an overlooking and
not a design feature.

The docs don't mention it anywhere. What they say is that a macro
parameter is either an RVALUE or an identifier. However, a file handle
*is* in a way an identifier as it a) uniquely identifies a file and b)
you can #ifdef, #ifndef and #undef it. So why the limitation?


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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On Tue, 22 Apr 2003 12:48:14 +0300, Peter Popov <pet### [at] vipbg> wrote:
> So why the limitation?

I have no idea but I imagine you can workaround it with passing it as string and
Parse_String() macro.

ABX

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Peter Popov wrote:
> 
> Then why can I #undef, #ifdef and #ifndef them? I mean, sure they are
> not normal identifiers, you can't assign to them etc. but the fact
> that you can't pass them to macros looks to me like an overlooking and
> not a design feature.

Dunno about #undef but the defined(FileHandle) function checks if the file
has reached the end while reading.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 28 Feb. 2003 _____./\/^>_*_<^\/\.______

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On Tue, 22 Apr 2003 11:53:36 +0200, ABX <abx### [at] abxartpl> wrote:

>I have no idea but I imagine you can workaround it with passing it as string and
>Parse_String() macro.

In this case the file handle should be global, which doesn't help
much.

I am rendering an animation. I read the data from a file, calculate an
iteration and write it back to the file. If the file is globally open
(the file handle is globally defined), it can only be open for reading
*or* writing/appending, which doesn't solve my case. The whole thing
is macro-based so the scene is just along the lines of

#include ...
#declare Object=Macro(Parameters)
camera... lights...

As you see, there's no way with this setup (and I *do* want it to be
like that because it's an include I'd like to release) that I can have
the file handle be global.

I consider this a genuine bug, not exactly along the lines of "it's
not working properly" but more like "there's an artificial limitation
which looks like it shouldn't be there".


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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In article <1ev9avov9b6hkd269fm74okpsdfq31kpg1@4ax.com> , Peter Popov 
<pet### [at] vipbg>  wrote:

> My question is: can I pass file handles as parameters to macros, and
> if yes, how?

No, because you cannot make copies of file handles for obvious reasons.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org

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On Tue, 22 Apr 2003 13:16:31 +0200, "Thorsten Froehlich"
<tho### [at] trfde> wrote:

>No, because you cannot make copies of file handles for obvious reasons.

But you can make references to them, right?


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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On Tue, 22 Apr 2003 13:16:16 +0300, Peter Popov <pet### [at] vipbg> wrote:
> > I have no idea but I imagine you can workaround it with passing it as string and
> > Parse_String() macro.
>
> In this case the file handle should be global, which doesn't help
> much.

You mean this working workaround does not help you ?

  #include "strings.inc"

  #macro Write(File_Handle)
    #write( Parse_String(File_Handle) , "test")
  #end

  #fopen ID1 "test1.txt" write
    Write("ID1")
  #fclose ID1
  #fopen ID2 "test2.txt" write
    Write("ID2")
  #fclose ID2

ABX

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On Tue, 22 Apr 2003 13:37:15 +0200, ABX <abx### [at] abxartpl> wrote:

>You mean this working workaround does not help you ?

I have to see. In your case it works. In my case, the file handle is
created within a macro which in turn has to pass it to other macros,
so I have to check the scope with which it is created.

In the meanwhile, I am already rendering with the ugliest workaround
possible -- I played parser and pasted the macro code with the
necessary parameters substituted, heh :)


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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