Edgecase | Typesetting: Code

The basic way to display code when writing an article is to enclose it within a

code

element. This is for code / data snippets and for the names of variables or tools. The

code

element will distinguish these visually from the surrounding text.

Example:

The <code>curl</code> tool can be used to download a webpage, like so:
<code>curl http://edgecase.net/articles/0</code>

This will be rendered as:

The

curl

tool can be used to download a webpage, like so:

curl http://edgecase.net/articles/0

When writing, it is often easier to use

code_lines

instead, which can have a newline before and after the enclosed item, making the result easier to read and check.

Example:

The <code>curl</code> tool can be used to download a webpage, like so:
<code_lines>
curl http://edgecase.net/articles/0
</code_lines>

This will be rendered as:

The

curl

tool can be used to download a webpage, like so:

curl http://edgecase.net/articles/0

The more complex way to display code is to use a

lined_code

element. This is designed to format a block of code (or an entire code file) for a web page in a readable way that can be manually copied / downloaded by the reader. The code itself should not be altered in any way, but simply copied into a new

lined_code

element, into the line just after the

data_lines

element.

Example:

<lined_code>
<code_title>Hello World in Python</code_title>
<language>python_2.7.13</language>
<line_numbers>yes</line_numbers>
<link>
<type>asset</type>
<filename>hello_world.py</filename>
<text>[download this code]</text>
<sha256>a73a174cc9d68c2351153c7f2324690b80c9b58b46a7fef605ee9b5f3be12ed6</sha256>
</link>
<data_lines>
#!/opt/local/bin/python

print "hello world"
</data_lines>
</lined_code>

Note: The asset link used here does not actually work. It is just an example.

This will be rendered as:

Hello World in Python

[download this code]

	#!/opt/local/bin/python

	print "hello world"

To avoid displaying line numbers, don't include the

line_numbers

element.

The

link

element is optional. If it is used, the code must be saved in a file and included as an asset of the article. This is for when the code is designed as a building block that will be used in the future. If it is just an example, made for illustration, there is no need to make it into an asset.

The

title

and

language

elements are also both optional.

If the

line_numbers

element exists and contains "yes", there is another optional element that can be included:

<first_line_number>21</first_line_number>

This is for ensuring that the correct line numbers are used when displaying an excerpt of a code file.

Example:

<lined_code> <line_numbers>yes</line_numbers> <first_line_number>21</first_line_number> <data_lines> n = g.order() secret = randrange( 1, n ) pubkey = Public_key( g, g * secret ) privkey = Private_key( pubkey, secret ) </data_lines> </lined_code>

This will be rendered as:

	n = g.order()
	secret = randrange( 1, n )
	pubkey = Public_key( g, g * secret )
	privkey = Private_key( pubkey, secret )

Here are several longer examples:

parse.asd

<lined_code> <code_title>parse.asd</code_title> <language>Common_Lisp</language> <data_lines> (asdf:defsystem :parse :description "" :author "" :license "" :version "" :serial t :components ((:file "packages") (:file "error") (:file "scope") (:file "parse"))) </data_lines> </lined_code>

This will be rendered as:

parse.asd

(asdf:defsystem :parse

  :description ""

  :author ""

  :license ""

  :version ""

  :serial t

  :components

    ((:file "packages")

     (:file "error")

     (:file "scope")

     (:file "parse")))

packages.lisp

<lined_code> <code_title>packages.lisp</code_title> <language>Common_Lisp</language> <line_numbers>yes</line_numbers> <data_lines> (defpackage :parse (:use :cl) (:export *root-scope* *active-scope* scope-error scope scope-name parent grandparent great-grandparent errors empty-p has-errors-p add-error close-scope execute-command print-scope content-scope content append-content container-scope children open-child keyword-scope parse)) </data_lines> </lined_code>

This will be rendered as:

packages.lisp

	(defpackage :parse
	(:use :cl)
	(:export
	root-scope
	active-scope
	scope-error
	scope
	scope-name
	parent
	grandparent
	great-grandparent
	errors
	empty-p
	has-errors-p
	add-error
	close-scope
	execute-command
	print-scope
	content-scope
	content
	append-content
	container-scope
	children
	open-child
	keyword-scope
	parse))

error.lisp

Note: The asset link used here does not actually work. It is just an example.

<lined_code> <code_title>error.lisp</code_title> <language>Common_Lisp</language> <line_numbers>yes</line_numbers> <link> <type>asset</type> <filename>error.lisp</filename> <text>[download this code]</text> <sha256>a73a174cc9d68c2351153c7f2324690b80c9b58b46a7fef605ee9b5f3be12ed6</sha256> </link> <data_lines> (in-package :parse) (defclass scope-error () ((value :initarg :value :initform nil :accessor value))) (defclass no-function-error (scope-error) ((name :initarg :name :reader name) (command :initarg :command :reader command))) (defmethod initialize-instance :after ((no-function-error no-function-error) &key) (setf (value no-function-error) (format nil "No function for command \"~A\" in scope ~A" (command no-function-error) (name no-function-error)))) (defun make-no-function-error (name command) (make-instance (quote no-function-error) :name name :command command)) </data_lines> </lined_code>

This will be rendered as:

error.lisp

[download this code]

	(in-package :parse)

	(defclass scope-error ()
	((value
	:initarg :value
	:initform nil
	:accessor value)))

	(defclass no-function-error (scope-error)
	((name
	:initarg :name
	:reader name)
	(command
	:initarg :command
	:reader command)))

	(defmethod initialize-instance
	:after ((no-function-error no-function-error) &key)
	(setf
	(value no-function-error)
	(format nil "No function for command \"~A\" in scope ~A"
	(command no-function-error)
	(name no-function-error))))

	(defun make-no-function-error (name command)
	(make-instance (quote no-function-error)
	:name name
	:command command))