wiki/cards/org-mode.org

Anki: Org mode

• org-babel
  • Front
  • Back
• org-babel modes
  • Front
  • Back
• Creating files with Org mode
  • Front
  • Back
• Dynamic content with Org mode
  • Front
  • Back
• Asciidoctor-styled callouts
  • Front
  • Back

org-babel

Front

What makes Org mode popular for reproducible research?

Back

org-babel, the library that enables superpowers for Org mode source code blocks.

Among the list of features, org-babel makes the following things easier for creating lab notebooks.

• Execute the source code block and print results.
• Create files from source code blocks, making it possible to create an entire computational report with a single Org mode document.
• Metaprogramming with noweb-inspired system making dynamic content possible.
• Individual control over source code blocks with sessions, export options, and variables.
• Pass values between different source code blocks even in different programming languages.

org-babel modes

Front

How to make org-babel pass values between different source code blocks?

Back

First, configure org-babel to work in functional mode (i.e., :results value) in a source code block. With functional mode, it will return values which will be handled by org-babel.

#+name: num
#+begin_src python  :results value
return 53
#+end_src

The value cannot be passed unless it has a name that others can reference yet so add a name property to the source code block (i.e., #+name: ${NAME}).

Now here's a different source code block written in a different language. To pass a value, you have to configure with :var ${VARNAME}=${NAME}.

#+begin_src ruby  :var num=num  :results output
print(num)
#+end_src

Creating files with Org mode

Front

How to create files with Org mode source code blocks?

Back

The :tangle option enables extracting code blocks into files. Accepted values include yes, no, or a relative path to the Org document where the file will be written.

Dynamic content with Org mode

Front

Is creating dynamic content possible? If so, how?

Back

Yes!

With source code blocks and the noweb option enabled, you can make meta-programming in Org. You can declare a function by assigning a name on the code block (i.e., #+name: ${FUNC_NAME}).

Here's an example of a source code block with a default argument.

#+name: greeting
#+header:  :var name="World"
#+begin_src sh
echo "Hello ${name}"
#+end_src

You can then call the function in different ways:

• For calling it inline, call_${FUNC_NAME}().
• For creating a block, #+call: ${FUNC_NAME}().
• For invoking inside a code block, <<${FUNC_NAME}()>>, but you have to enable noweb (e.g., :noweb yes).

You can then pass header arguments by appending in square brackets ([]) before invoking it — e.g., call_greeting[:results replaces](), #+call: greeting[:results replace](), <<greeting[:results replace]()>>.

Asciidoctor-styled callouts

Front

Are callouts possible? If so, how?

Back

Surprisingly, yes! It is just hidden on the documentation. Specifically, on the Literal examples section of the Org mode manual.

Here's an example to do it.

#+begin_src python
print("Hello world") # (ref:hello)
print(2 + 5)         # (ref:num)
#+end_src

In [[(hello)][line 1]], we have printed the traditional "Hello world" program.
In [[(num)][the second line]], we've done a simple arithmetic and printed it into the console.

To create Asciidoctor-styled callouts, create a reference inside of the code block and refer to it (i.e., (${ref})).