SGMLS::Output - Stack-based Output Procedures

       Copyright 1994 and 1995 by David Megginson, "dmeggins@aix1.uottawa.ca".  Distributed under the terms of
       the Gnu General Public License (version 2, 1991) -- see the file "COPYING" which is included in the
       SGMLS.pm distribution.

       This library allows redirectable, stack-based output to files, pipes, handles, strings, or nul.  It is
       especially useful for packages like SGMLS, since handlers for individual SGML elements can temporarily
       change and restore the default output destination.  It is also particularly useful for capturing the
       contents of an element (and its sub-elements) in a string.

       Example:

         sgmls('<title>', sub{ push_output('string'); });
         sgmls('</title>', sub{ $title = pop_output(); });

       In between, anything sent to output (such as CDATA) will be accumulated in the string returned from
       pop_output().

       Example:

         sgmls('<tei.header>', sub { push_output('nul'); });
         sgmls('</tei.header>', sub { pop_output(); });

       All output will be ignored until the header has finished.

       SGMLS::Output - Stack-based Output Procedures

       SGMLS.

perl v5.36.0                                       2022-10-13                                        Output(3pm)

         use SGMLS::Output;

       To print a string to the current output destination:

         output($data);

       To push a new output level to the filehandle DATA:

         push_output('handle',DATA);

       To push a new output level to the file "foo.data" (which will be opened and closed automatically):

         push_output('file','foo.data');

       To push a new output level to a pipe to the shell command "sort":

         push_output('pipe','sort');

       To push a new output level appending to the file "foo.data":

         push_output('append','foo.data');

       To push a new output level to an empty string:

         push_output('string');

       To push a new output level appending to the string "David is ":

         push_output('string',"David is ");

       To push a new output level to The Great Beyond:

         push_output('nul');

       To revert to the previous output level:

         pop_output();

       To revert to the previous output level, returning the contents of an output string:

         $data = pop_output();