plac/doc/emacs-integration.txt

..
  
  Multiline support and Emacs integration
  
  plac_ is optimized for the simplest use case and by default it provide
  support for simple command-line languages where a command take
  a single line. This is the simplest case: it is easy to keep
  track of the line number and to print it in the error message, if
  there is some error in a plac_ script. Starting from release 0.7
  plac_ is beginning to support multiline input: it is now possible
  to define command-line languages with commands spanning multiple
  lines. The topical use case is the implementation of a tool 
  to interact with a relational database: the tool must be able to send
  complex SQL queries spanning multiple lines to the backend.
  To support multiline input the ``Interpreter`` class provides
  a method ``multiline(stdin=sys.stdin, terminator=';', verbose=False)``
  which reads input from ``stdin`` until the terminator character
  (by default a semicolon) is reached.
  
  Since the Python readline module does not expose the
  multiline functionality of the underlying C library (which is there),
  plac_ multiline mode does not have readline functionality.  This is
  not a big deal really, because if you are writing multiple line
  commands you don't really want to type them at the command-line. It is
  much better to use a real editor to type them, and to call plac_ from
  the editor. Since I use Emacs I will give the recipe to integrate
  Emacs with plac_: something equivalent can be done for vi and for
  other editors/IDEs.
  
  The multiline mode can be enabled by invoking the plac_ runner with
  the ``-m`` option. Since the multiline mode is intended for use with
  Emacs in inferior mode, it does not print any prompt. Here is an example
  of usage::
  
   $ plac -m ishelve2.py
   set a 1;
   setting a=1
   show a;
   a = 1
  
  To integrate plac_ with Emacs, enters the following lines in your
  .emacs:
  
  .. include:: plac.el
     :literal: