[Dev-luatex] REQ: Please tell comp.text.tex why LuaTeX chose embed rather than extend.
jfine at pytex.org
Mon May 25 12:26:20 CEST 2009
Hans Hagen wrote:
>> In Python I can write
>> import pyscopg
>> and then I have a module that allows me to connect to a Postgres
>> database, and add, change and delete records. In other words I have
>> imported into Python a database extension.
> connect ... so the database itself runs indepently (and has a
> comunication channel to a certain amount of clients)
Yes, Hans. Pyscopg is a Python extension (probably written in C) that
can be imported as a module and which allows a Python script to connect
to a database (via a database server, of course).
>> But all this is a little off the topic of embed and extend. Postgres
>> can embed Python, and one can extend Python using Postgres. This is
>> the dual example, and it helps show us what embed is good for, and
>> what extend is good for.
> so, in your example its not even embedded or extended that we're talking
> of but connecting;
No, Hans, and my apologies for not being sufficiently clear in my
1. Pyscopg is a Python extension.
2. Postgres has an API that allows it to be used as a service.
3. Pysocpg is a Python extension that can connect to a Postgres database.
So it is 'extending Python (with a connection to a database)'.
> well, it is no secret that luatex provides sockets so
> you can start a luatex session, connect to it, send some text, and get
> back whatever you want, in the sense that you can serialize for instance
> a node list, (which in itself is not that useful as it lacks resources)
Yes, I agree. One can write Lua code that would allow LuaTeX to
function as a server, and some additional work would be required to make
that service useful. Or, because the C-libraries (used also by Lua)
support sockets, one could write an extension of TeX that functions as a
server. Each approach has its advantages and problems.
To return the dual-example provided by Postgres. I could, as you
suggest, write Lua code that allows LuaTeX to provide typesetting as a
service, via a socket interface. Here, I would be using Lua as an
embedded language in the typesetting program. It is akin to using a
"stored procedure" in a database program.
I could then wrap the API provided by LuaTeX (plus the code just
mentioned) in a module that could be imported, say, by Ruby. This would
be an example of extending a dynamic language (with a connection to a
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