codebraid 0.1.0

Live code in Pandoc Markdown

Codebraid – live code in Pandoc Markdown

Codebraid is a Python command-line program that enables executable code in Pandoc Markdown documents. Using Codebraid can be as simple as adding a class to your code blocks, and then running codebraid rather than pandoc to convert your document from Markdown to another format. codebraid supports almost all of pandoc's options and passes them to pandoc internally.

Codebraid currently can run Python 3.5+ code. Support for Julia, R, Rust, and several other languages is nearly ready for release.

Development: https://github.com/gpoore/codebraid

View example HTML output, or download it

Simple example

Markdown source test.md:

```{.python .cb.run}
print('Hello from Python!')
print('$2^8 = {}$'.format(2**8))
```

Run codebraid (to save the output, add something like -o test_out.md, and add --overwrite if it already exists):

codebraid pandoc -f markdown -t markdown test.md

Output:

Hello from Python! $2^8 = 256$

Installation and requirements

Installation: python3 setup.py install (or on some Windows installations and Arch Linux, python setup.py install).

Requirements:

• Pandoc 2.4+
• Python 3.5+ with setuptools and bespon 0.3 (bespon installation is typically managed by setup.py)

By default, the python3 executable will be used to execute code. If it does not exist, python will be tried to account for Windows and Arch Linux. Future releases will allow specifying the executable on systems with multiple Python 3 installations.

Converting a document

Simply run codebraid pandoc <normal pandoc options>.

Caching

By default, code output is cached, and code is only re-executed when it is modified. The default cache location is a _codebraid directory in the directory with your markdown document. This can be modified using --cache-dir. Sharing a single cache location between multiple documents is not yet supported.

If you are working with external data that changes, you should run codebraid with --no-cache to prevent the cache from becoming out of sync with your data. Future releases will allow external dependencies to be specified so that caching will work correctly in these situations.

Code options

Classes

Code is made executable by adding a Codebraid class to its Pandoc attributes. For example, `code`{.python}` becomes `code`{.python .cb.run}`.

• .cb.expr — Evaluate an expression and interpret the result as Markdown. Only works with inline code.

• .cb.run — Run code and interpret any printed content (stdout) as Markdown. Also insert stderr verbatim (as code) if it exists.

• .cb.nb — Notebook mode. For inline code, this is equivalent to .cb.expr. For code blocks, this inserts the code verbatim, followed by the stdout verbatim. If stderr exists, it is also inserted verbatim.

Keyword arguments

Pandoc code attribute syntax allows keyword arguments of the form key=value, with spaces (not commas) separating subsequent keys. value can be unquoted if it contains only letters and some symbols; otherwise, double quotation marks "value" are required. For example,

{.python key1=value1 key2=value2}

Codebraid adds support for additional keyword arguments. In some cases, multiple keywords can be used for the same option. This is primarily for Pandoc compatibility.

• session={string} — By default, all code is executed in a single, shared session so that data and variables persist between code chunks. This allows code to be separated into multiple independent sessions.

• hide={expr, code, stdout, stderr, all} — Hide some or all of the elements that are displayed by default. Elements can be combined. For example, hide=stdout+stderr. Note that expr only applies to .cb.expr or .cb.nb with inline code.

• show={expr, code, stdout, stderr, none} — Override the elements that are displayed by default. expr only applies to .cb.expr or .cb.nb with inline code. Elements can be combined. For example, show=code+stdout. Each element displayed can optionally specify a format from raw, verbatim, or verbatim_or_empty. For example, show=code:verbatim+stdout:raw.

  • raw means interpreted as Markdown.
  • verbatim produces inline code or a code block, depending on context. Nothing is produced if there is no content (for example, nothing in stdout.)
  • verbatim_or_empty produces inline code containing a single non-breaking space or a code block containing a single empty line in the event that there is no content. It is useful when a placeholder is desired, or a visual confirmation that there is indeed no output.

  The default format for all commands is verbatim, except for .cb.expr and inline .cb.nb, which default to raw.

• line_numbers/numberLines/number-lines/number_lines={true, false} — Number code lines in code blocks.

• first_number/startFrom/start-from/start_from={integer or next} — Specify the first line number for code when line numbers are displayed. next means continue from the last code in the current session.