Daniel Bohrer: "Slides"

2016-10-14T20:07:31Z

"Slides"

Neue Seite

<pre>

____ _ _ __ __ _
/ ___| ___ _ __ ___ __ _ _ __ | |_(_) ___ | \/ | __ _ _ __| | ___ _ _ __
\___ \ / _ \ '_ ` _ \ / _` | '_ \| __| |/ __| | |\/| |/ _` | '__| |/ / | | | '_ \
___) | __/ | | | | | (_| | | | | |_| | (__ | | | | (_| | | | <| |_| | |_) |
|____/ \___|_| |_| |_|\__,_|_| |_|\__|_|\___| |_| |_|\__,_|_| |_|\_\\__,_| .__/
|_|
with the M4 macro processor

</pre>
= M4 =

* Kernighan & Ritchie, 1977
* part of almost every Unix/Linux distribution
* Heavily used in GNU <code>autotools</code>
* Simple mechanism:
** define macros
** when macro token is found in input, replace token with definition
** write input to output

= Example 1: Hello World(?) =

<pre>$ cat 01-helloworld.m4
define(HELLO, Ohai)dnl
HELLO world.</pre>
<pre>$ m4 01-helloworld.m4
Ohai world.</pre>
Notes:

* <code>dnl</code>: Discard to Next Line
** "comments"
** prevents unwanted whitespace in output

= Example 2 =

<pre>$ cat 02-more-hello.m4
define(Nice, Happy)dnl
define(HELLO, Nice to meet you)dnl
HELLO World.</pre>
<pre>$ m4 02-more-hello.m4
Happy to meet you World.</pre>
What happened?

= Example 2: step by step =

{|
!width="50%"| Input
!width="50%"| Macro definitions
|-
|
<pre>> define(Nice, Happy)dnl
define(HELLO, Nice to meet you)dnl
HELLO World.</pre>
|

|}

{|
!width="50%"| Input
!width="50%"| Macro definitions
|-
|
<pre>>
define(HELLO, Nice to meet you)dnl
HELLO World.</pre>
|
# Nice → Happy
|}

{|
!width="50%"| Input
!width="50%"| Macro definitions
|-
|
<pre>
> define(HELLO, Nice to meet you)dnl
HELLO World.</pre>
|
# Nice → Happy
|}

{|
!width="50%"| Input
!width="50%"| Macro definitions
|-
|
<pre>
> define(HELLO, Happy to meet you)dnl
HELLO World.</pre>
|
# Nice → Happy
|}

{|
!width="50%"| Input
!width="50%"| Macro definitions
|-
|
<pre>
>
HELLO World.</pre>
|
# Nice → Happy
# HELLO → Happy to meet you
|}

{|
!width="50%"| Input
!width="50%"| Macro definitions
|-
|
<pre>

> HELLO World.</pre>
|
# Nice → Happy
# HELLO → Happy to meet you
|}

{|
!width="50%"| Input
!width="50%"| Macro definitions
|-
|
<pre>

> Happy to meet you World.</pre>
|
# Nice → Happy
# HELLO → Happy to meet you
|}

= Expansion Rules (1) =

# Macro expansion is recursive
#* macros inside of macros are evaluated first (unless quoted)
#* <code>define</code> is a macro itself

But maybe we don't want that.

= Quoting =

Quoting prevents unwanted macro replacement

<pre>$ cat 03-quoting.m4
define(`Nice', `Happy')dnl
define(`HELLO', ``Nice' to meet you')dnl
HELLO World.

$ m4 02-quoting.m4
Nice to meet you World.</pre>

= Parametric Macros =

<pre>$ cat 04-params.m4
define(`HEADING', `<h1 id="$1">$2</h1>')dnl
define(`PARA', `<p id="$1">$2</p>')dnl
define(`ITALIC', `<i>$1</i>')dnl
dnl
HEADING(title, `This is the title')
PARA(first_para, This is rendered as text. Parameters can even span
multiple lines. If you include commas`,' be sure to include quotes.)
PARA(second_para, This is normal text. ITALIC(This is italic.))</pre>
<pre>$ m4 04-params.m4
<h1 id="title">This is the title</h1>
<p id="first_para">This is rendered as text. Parameters can even span
multiple lines. If you include commas, be sure to include quotes.</p>
<p id="second_para">This is normal text. <i>This is italic.</i></p></pre>

= Expansion Rules (2) =

# Quoted text is simply stripped of the quotes
# Macro expansion is recursive
#* macros inside of macros are evaluated first (unless quoted)
#** inner macros can generate more parameters for outer macros
# Leading whitespace of parameters is removed
# The expansion of a macro is always re-evaluated
#* read: "strip one layer of quoting, or expand again"

Rule of thumb:

* One quoting level per parentheses.

= You probably noticed =

M4 macros are a great way to build semantic markup.

* Semantics:
** Wikipedia: “the linguistic, and also philosophical study of meaning”
** more than only formatting
** ideally machine-readable

= For example =

* Write your meeting minutes in Markdown, using a “public macro interface” for e.g.:
** votes
** resolutions
** TODOs
* Write an M4 library for each output
** define the “public macro interface” accordingly
* Use the markup with multiple M4 “libraries” to convert your minutes to:
** human-readable formats like Markdown
*** with consistent formatting
*** via pandoc: HTML, ReST, LaTeX, PDF, …
** machine-readable formats like JSON, CSV, XML, …

See: https://github.com/rohieb/minutes-m4rkup

= example.m4rkdown =

<pre>MEETING_MINUTES(Board meeting, 2016-09-01, 20:00,
[Adam Ant, Henrietta Horse, Beatrice Bull], [Ephraim Elephant], [Adam Ant])

We talked about things for a while.

* RESOLUTION(Resolution 2016-00, VOTE_ADOPTED(3,0,0), World Domination)
* TODO(T2016-03, Adam Ant, Build Doomsday Machine)
* Recent TODOs:
* TODO(T2016-02, , Try out LAZZZORs from Evil Corp., [
* They make nice, cheap LAZZZORS
* LAZZZORS are needed for Doomsday Machine])
* DONE(T2016-01, Beatrice Bull, Buy some space rockets)
END(21:00)</pre>

= example.markdown =

<pre>Board meeting 2016-09-01
========================

* Starting time: 20:00
* Attending: Adam Ant, Henrietta Horse, Beatrice Bull
* Absent: Ephraim Elephant
* Minute taker: Adam Ant

We talked about things for a while.

* __Resolution 2016-00 ✔ (3|0|0):__ World Domination
* __TODO Adam Ant:__ Build Doomsday Machine
* Recent TODOs:
* __TODO:__ Try out LAZZZORs from Evil Corp..
* They make nice, cheap LAZZZORS
* LAZZZORS are needed for Doomsday Machine
* ~~__DONE Beatrice Bull:__ Buy some space rockets~~
* Ending at 21:00</pre>

= example.json =

<pre>{
"metadata": { "type": "Board meeting","date": "2016-09-01", "start_time": "20:00",
"attendants": "Adam Ant, Henrietta Horse, Beatrice Bull",
"absentees": "Ephraim Elephant", "keeper_of_minutes": "Adam Ant"
},
"content": [
{ "type": "resolution", "public": true, "ref": "Resolution 2016-00",
"vote": { "approved": true, "pro": 3, "contra": 0, "abstain": 0 },
"text": "World Domination", "allocated_money": "", "notes": ""
},
{ "type": "todo", "public": true, "done": false, "ref": "T2016-03",
"assigned": "Adam Ant", "text": "Build Doomsday Machine",
"notes": "" },
{ "type": "todo", "public": true, "done": false, "ref": "T2016-02",
"assigned": "", "text": "Try out LAZZZORs from Evil Corp.", "notes":"
* They make nice, cheap LAZZZORS
* LAZZZORS are needed for Doomsday Machine"
},
{ "type": "todo", "public": true, "done": true, "ref": "T2016-01",
"assigned": "Beatrice Bull", "text": "Buy some space rockets", "notes": ""
}
],
"end_time": "21:00"
}</pre>

Benutzer:Daniel Bohrer/Semantic M4rkup - Versionsgeschichte

Daniel Bohrer: "Slides"