This Emacs package provides a mechanism for REPLs (or comint buffers, in Emacs parlance) to display graphics and other types of special content.
The main motivation behind this package is to display plots in the Python shell. However, it does more than that.
First, it is not constrained to graphics, and can display other “MIME attachments” such as HTML and LaTeX content. In fact, the Python backend of the package implements IPython’s rich display interface. A use-case beyond the displaying of graphics would be to render dataframes as HTML tables; this opens up the possibility of typographical improvements over the usual pure-text representation. You can also easily define rich representations for your own classes.
Second, the package defines a flexible communication protocol between
Emacs and the inferior process, and, consequently, can be extended to
other comint types. Currently, besides Python, there is support for
the regular (Unix) shell. In this case, a special command, mimecat,
is provided to display content. Again, this works for images, HTML,
LaTeX snippets, etc.
To start enjoying comint-mime, simply call M-x comint-mime-setup
from a supported buffer (which, at the moment, are the M-x shell and
M-x run-python buffers). To apply this permanently, add that same
function to the appropriate mode hook:
(add-hook 'shell-mode-hook 'comint-mime-setup)
(add-hook 'inferior-python-mode-hook 'comint-mime-setup)Note that for Python it is important to use the IPython
interpreter. It can be configured to have the same look-and-feel as
the classic python program as follows.
(when (executable-find "ipython3")
(setq python-shell-interpreter "ipython3"
python-shell-interpreter-args "--simple-prompt --classic"))To add support for new MIME types, see comint-mime-renderer-alist.
To add support for new comints, an entry should be added to
comint-mime-setup-function-alist. This function should arrange for
the inferior process to emit an escape sequence whenever some MIME
content is to be displayed.
The escape sequence has the following shape:
ESC ] 5 1 5 1 ; header LF payload ESC \
Here, header is a JSON object containing, at least, the entry
type, which should be the name of a MIME type. Other header entries
can be passed; the interpretation is up to the rendering function.
The payload can be either the content of the attachment, encoded in
base64 (which is decoded before being passed to the selected
renderer), or a file:// URL (whose content is read and passed to the
renderer), or yet a tmpfile:// URL, which indicates that the file
should be deleted after it is read.
Note that it can take considerable time to insert large amounts of data in a comint buffer, specially if it contains long lines. Consider using a temporary file for large data transfers.
- It should be possible to support at least Matplotlib in the standard Python interpreter.
- Improve the HTML rendering for numeric tables
Discussions, suggestions and code contributions are welcome! Since this package is part of GNU ELPA, contributions require a copyright assignment to the FSF.