Support for `\newenvironment` wrapping another environment about pylatexenc HOT 3 OPEN

Thanks! I have tested the master branch and can confirm that the parsing error is gone. :)

I also noticed that now (and also with my proposed workaround) the resulting node representation is kind of screwed up and subsequent latex code is still regarded as belonging to the \newenvironment command. Do to coincidence, this does not bother me in my special use case, so I am happy as soon as I can parse the file without exceptions.

I guess in general it is still desirable to be able to parse \newenvironment properly and represent \begin and \end commands in the arguments in some reasonable way.

FYI: My use case is a LaTeX to text script that supports all the special macros I usually use and can handle includes with the standalone package. That includes some hacks to throw away the preambles from imported documents and lots of special formatters for custom commands. So in this case, I do not want \newcommand definitions to be parsed and applied like latexpp does, but I am perfectly happy with having a parsed node list that I can transform as needed.

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Hi and thanks for the report. There are two points to unpack here.

First, you're seeing an error mainly because pylatexenc does not really support the \newcommand/\newenvironment family of commands (see my comment in issue 48). It attempts to parse the arguments to \newenvironment like LaTeX blocks of text; it doesn't record in any way the new command or new environment for future parsing. In most cases you might not see any errors in tolerant parsing mode, but what really happens is that the \newcommand/\newenvironment instruction gets ignored (it gets parsed as a simple macro node and then converted to empty text), and then later in the document custom macros are handled using the default behavior for unknown macros or environments (which might or might not give you the desired behavior). I have plans for better support of \newcommand/\newenvironment commands, but they haven't been fully implemented yet. I've written some (experimental) code in my other project latexpp that expands some commands defined by \newcommand/\newenvironment. Depending on your use case, you might be able to reuse some code from https://github.com/phfaist/latexpp/blob/master/latexpp/fixes/newcommand.py for your purposes.

On the other hand, the additional exception you're seeing ("AttributeError: 'LatexWalkerEndOfStream' object has no attribute 'open_contexts'") is a bug and I'll look to fix it. Thanks for reporting.

from pylatexenc.

My latest commit should fix the weird chained exception that you reported. I'm leaving the issue open as an enhancement to enable \newenvironment wrapping another environment. This should be support once I get the \newcommand family of friends supported. (See also #48.) Thanks for reporting!

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