So, I thought I had a brainwave....

I generally don't bother with FH type filehandles, but open $FH, ...., and use $FH instead.

Problem is handling STDERR etc. the same way.

Simple approach is to simply do:

  $STDERR = *STDERR{IO} ;

at some early stage, and use $STDERR thereafter. I do this in a module along with my other favourite bits and pieces, and export $STDERR et al.

I just read that exporting variables is a Bad Thing. So I tried another approach. I tried creating a STDERR subroutine, which returns *STDERR. Stripping down to the basics, and adding a little test stuff, this looks something like:

  use strict ;
  use warnings ;

  sub STDERR { *STDERR } ;

  p(STDERR, "---Hello world: '", STDERR, "'\n") ;

  print STDERR "+++STDERR: '", STDERR, "'\n" ;

  sub p { my ($H, @p) = @_ ; print $H "//[$H] ", @p ; } ;
[download]

and the result is, STDERR:

  //[*main::STDERR] ---Hello world: '*main::STDERR'

and, STDOUT:

  *main::STDERR

Which indicates that STDERR() is doing what was hoped for. So far so good. The sad part is that STDERR is no longer working as a filehandle ! At least as far as print is concerned.

What's really odd is that the parser appears to have accepted the print STDERR as a filehandle -- for if not, there would have been a lot of compile time complaints about possible missing operator ! However, something clearly goes wrong -- and there are no errors or warnings raised. Quite independently of whether this trick "should" work, the current behaviour looks like a failure of diagnostics at least.

FWIW, it occurred to me that sub STDERR ought to look like a constant, thus:

  use strict ;
  use warnings ;

  sub STDERR () { *STDERR } ;

  p(STDERR, "---Hello world: '", STDERR, "'\n") ;

  print STDERR "+++STDERR: '", STDERR, "'\n" ;

  sub p { my ($H, @p) = @_ ; print $H "//[$H] ", @p ; } ;
[download]

but Perl throws up all over that, as follows:

  String found where operator expected at tst.pl line 8, near "STDERR 
+"+++STDERR: '""
        (Do you need to predeclare STDERR?)
  syntax error at tst.pl line 8, near "STDERR "+++STDERR: '""
  Execution of tst.pl aborted due to compilation errors.
[download]

...which seems to indicate that I'm upsetting something !

Wadya think ?

Chris

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