Responding to [[http://irreal.org/blog/?p=6924][yesterday's post]], Sacha asks if I could post the code for
=jcs-insert-url= for others to use. I thought I'd already done that but
apparently not. That's probably because except for the part identical to
=jcs-get-link=, which I /did/ [[http://irreal.org/blog/?p=2895][write about]], it's pretty trivial. In any event,
here it is:
(defun jcs-insert-url ()
"Insert URL of current browser page into Emacs buffer."
The =jcs-retrieve-url= function does all the work, of course, and is
just the code that I abstracted out of =jcs-get-link= to actually
retrieve the URL from Safari:
(defun jcs-retrieve-url ()
"Retrieve the URL of the current Safari page as a string."
"osascript -e 'tell application \"Safari\" to return URL of document 1'")))
One obvious problem with all this is that it works only for macOS. Not to
despair, though, because in the comments to the original post, [[http://irreal.org/blog/?p=6924#comment-3732979999][Brad Collins
suggests a solution]] that uses [[https://github.com/xuchunyang/grab-x-link][grab-x-link]] to do the same thing for FireFox and
Chrome on other systems. Be sure to read Brad's comment because there is---or at
least was---an issue with the MELPA version.
Finally, Sacha took the part about looking for ways to make your workflow easier
seriously and came up with a bit of Elisp to [[http://sachachua.com/blog/2018/01/org-mode-inserting-a-function-definition/][insert a function definition at the
point]], regardless of where it's defined. That's very handy and I immediately
stole her code and used it to insert the two functions above. My old method was
to switch to =init.el=, find the function, copy it to the kill ring, switch back
to the original buffer, add the source block fences, and insert the code between
them. Sacha's code did all of that for me and I didn't even have to leave my
current buffer. That's splendid. If you find yourself having to add function
definitions to your text, be sure to read Sacha's post. It will save you a lot
** Calc for Programmers :IRREAL:
:CREATED: [2018-08-05 Sun 10:04]
After writing about Florian Adamsky's post on [[http://irreal.org/blog/?p=7040][acronyms in AUCTeX]], I snooped
around on his site and came across a [[https://florian.adamsky.it/2016/03/31/emacs-calc-for-programmers-and-cs.html][nice post]] on [[https://www.gnu.org/software/emacs/manual/html_node/calc/index.html][Emacs Calc]] from a programmer's
and computer scientist's point of view. As regular readers know, I've been
working to increase my calc-fu lately so I read the post with interest.
Adamsky demonstrates some of the Calc functions that are useful to programmers
and computer scientists. This includes such things as entering and displaying
numbers in various radixes and performing the standard logical operations on
(the usually binary representation of) numbers. He even shows how to add a new
“units” representation to Calc---in this case bits/bytes/bits per second.
Calc is a large subsystem and famously hard to master but worth the effort. It's
been described as a “poor man's Mathematica.” It's not nearly as powerful as
Mathematica, of course, but it's surprising how many things it can do. If you're
a programmer/computer scientist and an Emacs user you should spend a little time
investigating Calc. It really can make your life easier. An easy way to get
started is to read Adamsky's post. It covers only a small slice of Calc but will
give you an idea of its power.
** Parsing with ~org-element~ :IRREAL:
:CREATED: [2018-08-10 Fri 17:55]
@ -137,105 +63,6 @@ The relevant code:
'(("" "total:" ":=vsum(@2..@-1);T" "")))
** Emacs Lisp Byte-Code :IRREAL:
:CREATED: [2018-08-11 Sat 21:40]
Very few Emacs users---no matter how advanced---ever need to worry about the
specifics of the Elisp bytecode, or even, for that matter, that it
exists. Still, as guys like Chris Wellons [[http://nullprogram.com/blog/2014/01/04/][have shown]], it can sometimes be useful
to have a basic understanding of the bytecodes.
R Bernstein has put together a comprehensive, book-length [[http://rocky.github.io/elisp-bytecode.pdf][documentation on Elisp
bytecodes]]. After a short introduction, the documentation considers the bytecode
environment including the compiler, interpreter, and bytecode optimization. Then
there's a long section on the individual bytecode instructions.
Finally, there are sections on the changes in bytecodes between Emacs versions,
a table of opcodes, and a reference section. There's also a GitHub repository of
the [[https://github.com/rocky/elisp-bytecode][document source]].
As I said, you probably will never need this but if you do, you'll be /very/
glad to have Bernstein's documentation. It's another example of the vibrant
** Formatting Tables :IRREAL:
:CREATED: [2018-10-28 Sun 09:13]
If you're like me, you automatically think of the Org mode table editor (or
Orgtbl minor mode) when you think of tables in Emacs. It's hard to beat that
functionality and Orgtbl mode makes it available everywhere in Emacs, even if
you're not in an Org buffer. Sometimes, though, you'd like to have special
formatting for some or all of the table. That's where =delim-col= comes in.
=Delim-col= is /built-in/ Emacs functionality that allows you to do things like
adjust what string separates the columns, add a beginning or ending string to
each item, add an ending string for each row, and adjust the padding in the
table. It can be really handy for copying and pasting and then reformatting
tables from an external source.
I didn't know about =delim-col= until I read about it [[https://emacsnotes.wordpress.com/2018/09/24/delim-col-a-handy-tool-for-creating-pretty-tables-and-converting-those-to-different-table-formats/][over at Emacs Notes]], where
you'll find a good explanation of the facility and what it can do. The Emacs
Notes post also offers at bit of Elisp to make choosing the strings and
delimiters a bit easier. By default you have to set them using a series of
=setq= statements if you want something different from the built-in choices. The
Emacs Notes codes arranges for you to be prompted for the values.
You probably won't need the =delim-col= functionality very often but when you do
it's much easier than using something like a keyboard macro. Take a look at the
post and see if you don't agree.
** Org Mode Cookbook :IRREAL:
:CREATED: [2018-08-04 Sat 12:51]
Way back in 2014, I [[http://irreal.org/blog/?p=2575][posted]] about Eric Neilsen's excellent [[http://ehneilsen.net/notebook/orgExamples/org-examples.html][Emacs org-mode
examples and cookbook]]. I recently came across a reference to it and was reminded
what a great resource it is. It's easy to browse through and just read one or
two entries when you have time. In skimming through it, I learned---or perhaps
relearned---how to [[http://ehneilsen.net/notebook/orgExamples/org-examples.html#sec-10][insert in-line calculations in a document]].
As I wrote in the original post, Neilsen is a researcher and his cookbook is
oriented at using Org mode to produce documents of various types. Still, that
covers a lot of territory and there are many good examples of powerful Org mode
use cases in it. The Document has moved or, really, taken up a second
residence. It was originally hosted at [[http://fnal.gov/][Fermilab]], where Neilsen works, and it's
still there but it's also available at his own site. The two documents are
identical so it doesn't matter if you use the new link or the original one
pointing to FNAL.
If you're an Org user, especially if you use Org to produce documents,
you should take a look at Neilsen's cookbook and bookmark it for future
** How to paste then copy
:CREATED: [2018-08-11 Sat 21:47]
Question: how to set a mark such that all subsequent copy operations move their