Extending the Translator

In an earlier section is was seen how the capabilities of L^ATEX2HTML can be extended to cope with L^ATEX commands defined in packages and style-files. This is in addition to defining simple macros and environments, using \newcommand and \newenvironment. The problem however, is that writing such extensions for packages requires an understanding of Perl programming and of the way the processing in L^ATEX2HTML is organised.

The default behaviour for unrecognised commands is for their arguments to remain in the HTML text, whereas the commands themselves are passed on to L^ATEX, in an attempt to generate an image. This is far from ideal, for it is quite likely to lead to an error in L^ATEX due to not having appropriate arguments for the command.

Currently there are several related mechanisms whereby a user can ask for particular commands and their arguments to be either

• ignored (via: &ignore_commands);
• passed on to L^ATEX for processing as an image
  (via: &process_commands_in_tex);
• passed to L^ATEX for processing as an image, as if an environment
  (via: &process_commands_inline_in_tex);
• passed on to L^ATEX, setting parameters to be used in subsequent images
  (via: &process_commands_nowrap_in_tex);
• processed as ``order-sensitive'', as if an environment rather than a command
  (via: &process_commands_wrap_deferred);

The string beginning &.... is the name of the Perl subroutine that controls how the L^ATEX commands are to be subsequently treated during processing by L^ATEX2HTML. Towards the end of the latex2html script, one finds a list of L^ATEX commands to be handled by each of these subroutines. These lists even include some common TEX commands.

Analogous lists occur in most of the package extension files. In many cases the commands are for fine-tuning the layout on a printed page. They should simply be ignored; but any parameters must not be allowed to cause unwanted characters to appear on the HTML pages. Customised extensions using these mechanisms may be included in the $LATEX2HTMLDIR/latex2html.config file, or in a personal $HOME/.latex2html-init initialisation file, as described next.