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Macros in rest2web

Using Macros

About macros

Macros allow you to use a shorthand for often-used text or HTML.

As a simple example, let's say that I use a certain link a lot. I don't want to type it over and over again. I can define a macro foo to include this link every time I type {foo}:

foo = 'My link'

In this case, the "macro definition" is simply a string that contains the HTML we want to substitute. We can use more sophisticated macros, though.

Let's assume that I use acronyms a lot, and I'm getting tired of having to type that tag again and again. It would be nice if I could type something like {acronym;IMO;In My Opinion}

which expands to IMO. (Move your mouse over the "IMO" to see the effect. Not all browsers may support this.)

To achieve this, we define a simple Python function:

def acronym(acronym, meaning):
    return '<acronym title="%s">%s</acronym>' % (
           meaning, acronym)

{acronym;IMO;In My Opinion} is equivalent to the function call acronym("IMO", "In My Opinion").

These macros can also be used to do more complex things, like insert pictures, include whole files etc.

Where are macros defined?

In the rest2web config file you can specify a path to a macros module. This can have any name - but it should be a module that Python can import. Basically that means the filename has to end in '.py' [1].

So, to get started, here's what you need to do:

  • Create a file called macros.py. You probably want to start with a copy of the example one.
  • Add definitions to it. (It helps if you know some Python, of course, but even without that you can enter simple string macros of the form name = 'text'.)
  • Put the location of this file in the rest2web config file for your site.

Things you should know

  • If you don't want to use macros then set macros = "" in the config file. If you do this, rest2web won't attempt any macro conversions.
  • Macros are string-based. If a macro's return value isn't a string, then it's turned into one (if at all possible).
  • Arguments for a function call are strings too; {foobar;42} is the function call foobar("42"), not foobar(42). If you want a different type, you'll have to explicitly convert in inside your function.
  • Functions with no arguments are called by their name: {baz} is equivalent to baz(), if baz is a callable object. If not, then the value is taken.
  • If a macro name isn't found, it is left alone. In fact, this piece of documentation exists as it is because of this rule. Text like {knarf} would be replaced' if it was a macro. Since we didn't define a macro knarf, it is left alone and shows up in text with curly braces and all.
  • If an error occurs in a macro (function call), it is left alone as well. So are macros containing newlines.
  • If you want to include a semicolon (;) or a curly brace in your arguments, you're out of luck. There are currently no ways to do this. You can always define escape sequences in your functions of course.
  • Ditto if you want to suppress a macro call that would normally be substituted. other than the {curlyl}, and {curlyr}, macros. See The Example Macros below.
  • Macros map to Python objects. Usually you'll want to use strings or functions, but other objects are possible as well.
  • If you define a function you can also give it a shorter name. For example, to give our smiley function the shorter name sm, I included the line sm = smiley after the function definition.

The Order

Macros are resolved after the pages has been processed by docutils [2]. This means your macros should return html for direct inclusion in the final page.

They are resolved before the page is passed to the template engine. This means that dynamic values like <% path_to_root %> output by macros will be resolved.

Filepaths

Before the macros are run, the current directory is changed to be the same as the macros file. This means all file paths supplied to macros should be relative to this file.

Modules

The modules directory in the rest2web distribution includes various Python modules used by the macros. If you aren't using macros then you don't need this directory. Credits for all the modules here are in the Credits section below.

This directory is put in the Python search path. If you move them elsewhere you should make sure they are on the sys.path. If you don't know what I'm on about then leave them where they are Very Happy

Advanced Macros

As well as the normal macros discussed above, there is a more advanced system of macros as well. This allows you to apply a macro to a whole chunk of text. Unlike the simple macros, these macros can be nested to apply several effects to passages.

The advanced macros work by enclosing a passage of text between a {+macro} and a {-macro}. The macro is applied to all the text between the + and the -. In this case it would be applied to and a.

You can also nest them So you can do things like :

{+second}{+first} The text {-second}{-first}

{+whole} Some text {+part} a bit in the middle {-part} more text{-whole}

These macros aren't the same as normal macros though. Here's the idea. While a regular macro {f;x;y} translates to a function call f("x", "y"), the + and - versions use a class definition. A simple example :

class rot13(textmacros.BaseMacro):
     def open(self, text):
         return text.encode("rot13")

Once this is defined, in your macros file (or just imported into it), you can use it as follows :

The solution is {+rot13}not for your eyes{-rot13}.

Upon execution, this will convert the text between the rot13 tags. This becomes :

The solution is abg sbe lbhe rlrf.

In your class the +tag corresponds to the class's open(text) method, the -tag to the close() method.

Note that if you are using docutils to process your text then it will be processed by docutils before it is processed by the macro. If you want to bypass this, and pass the text to your macro only, then you need to use the .. raw:: html directive. e.g. :

.. raw:: html

    {+rot13}
    this text will *not* be processed as reST
    {-rot13}

The Example Macros

The macros.py that comes with rest2web contains several useful macros. Feel free to experiment with this file. You can modify the macros in it, or use them as examples to create your own.

curlyl and curlyr

These two macros perform simple substitution. They are a way of including curly left hand brackets and curly right hand brackets in your pages. They are also have the shorter forms cl and cr.

For example, to include {example} in your page - without it being interpreted as a macro - you can write {curlyl}example{curlyr} or {cl}example{cr}.

This came in very handy when creating this page Laughing

smiley

This is one of the nicest macros. It uses a modified version of smiley.py by Mark Andrews to put smilies onto your site. You will need to modify macros.py with the right path to the smilies directory (on disk) and the right path to the smiley images (on your site). You can use sm as a shorter alias for smiley.

Examples :

{smiley;:-)} becomes Smile

{sm;:roll:} becomes Rolling Eyes

It will read standard smiley packages like the ones used by phpbb. Download more from the stylesdb site.

You can see a full list of all of the smilies from the example set in the Smilies Page.

acronym

We`ve seen this in the first example. {acronym;acronym;meaning} produces acronym. You can also use {acro;acronym;meaning}.

As an added bonus there are a few standard acronyms that can be called without the acronym definition. These are :

# a dictionary of standard acronyms
# keys should be lowercase
acronyms = {
    'wysiwyg' : 'What You See Is What You Get',
    'html' : 'HyperText Markup Language',
    'xml' : 'eXtensible Markup Language',
    'xhtml' : 'eXtensible HyperText Markup Language',
        }

So you can do {acro;WYSIWYG}, which becomes WYSIWYG Cool . Feel free to add your own of course.

emoticon

This is another shorthand way of including images in your pages. It's useful for putting emoticons inline with text - hence the name. Unlike the smiley macro it doesn't need to read anything of disk. It assumes the files you are including are all 'gif's and located in the <% path_to_root %>images/ directory of your website. These are hardwired into the emoticon function - so you can edit them there if you want to.

Warning

Including images without specifying a size may slow down the browser rendering of your pages. You could make all your images the same size and hardwire the sizes into the 'img' tag that this macro creates. Alternatively you could do something clever with the PIL by Frederik Lundh - and have it work out the sizes and insert them for you.

Examples :

{emoticon;eyeballz} becomes emoticon:eyeballz

{emo;noise} becomes emoticon:noise

You can use emo as a shorter alias for emoticon.

include

This macro is very simple. Give it a filepath (relative to the macro module) and it will include the contents of that file into this page. The optional 'escape' parameter allows you to escape whitespace. This will insert files as they are - without having to use the '<pre>' tag, which breaks my layout - have I mentioned that before ? Wink

For example <tt>{include;rest2web.ini;True}</tt> escapes the rest2web.ini file and inserts it into the page :

# Attempt to use psyco ?
psyco = True

# pause after building ?
pause = True

# the root directory
start_directory = 'docs'

# the directory to generate files in
target_directory = 'docs_html'

# directory to compare against (defaults to target_directory)
compare_directory = ''

# file to log output to (if any)
log_file = 'log.txt'

# file containing macros (if any)
macros = 'macros.py'

# Enter DEBUG mode ?
# (Interactive interpreter prompt in each page namespace)
DEBUG = False

You can use inc as a shorter alias for include.

To include HTML files (without escaping), use {include;some_file.html}.

colorize

This macro takes a file and applies Python syntax highlighting to it. You need the right rules in your CSS file for the coloring to be visible. See the rules that start py in test.css.

{colorize;docs/example_function.txt} becomes :

#
# syntax coloring
try:
    import colorize as col
except ImportError:
    def colorize(filename):
        raise ImportError, 'Importing colorize.py failed.'

else:
    def colorize(filename):
        """
        format a python script as html
        Using the appropriate css it will be nicely colored.

        Needs the colorize.py module.
        """

        fullname = os.path.join(filename)
        f = open(fullname, 'r')
        data = f.read()
        f.close()

        p = col.Parser(data)
        p.format(None, None)
        src = p.getvalue()
        return src.replace('\n', '<br />\n').replace('  ', '&nbsp;&nbsp;')
        # to avoid having to use <pre>..

You can use col as a shorter alias for colorize.

To use the colorize macro, you need the right definitions in your CSS. Something like :

.pysrc {
    border: #c0c0ff 2px dotted;  padding:10px;
    font-weight: normal; background: #e0e0ff; margin: 20px;
    padding:10px;
}

.pykeyword {
    font-weight: bold;
    color: orange;
}
.pystring {
    color: green
}
.pycomment {
    color: red
}
.pynumber {
    color:purple;
}
.pyoperator {
    color:purple;
}
.pytext {
    color:black;
}
.pyerror {
    font-wieght: bold;
    color: red;
}

Change the color definitions to alter the appearance.

+/- coloring

This is the only example of an advanced macro included. It does the same job as the colorize macro, but instead of passing it a filename - it works on the text it encloses. This :

.. raw:: html

    {+coloring}
    class coloring:
        """A Macro for coloring chunks of text."""
        def open(self, data):
            p = color.Parser(data)
            p.format(None, None)
            src = p.getvalue()
            src = src.replace('\n', '<br />\n')
            return src.replace('  ', '&nbsp;&nbsp;')

        def close(self, *args):
            pass
    {-coloring}

Becomes :

class coloring:
    """A Macro for coloring chunks of text."""
    def open(self, data):
        p = color.Parser(data)
        p.format(None, None)
        src = p.getvalue()
        return src.replace('\n', '<br />\n').replace('  ', '&nbsp;&nbsp;')

    def close(self, *args):
        pass

small

This macro puts the enclosed text between <small>.... </small> tags. This is a feature missing from docutils.

<cl}small;Some text that we would like to make smaller} becomes Some text that we would like to make smaller.

name

This macro inserts a named anchor tag. This means you can link to the tag using the name you provide.

{name;anchor} would insert the following HTML - <a name="anchor" id="anchor"></a>.

You link to it using the HTML - <a href="#anchor">Link to Anchor</a>.

title

This is a shortcut for inserting headlines. You pass in the text and the size (which defaults to an h3 headline).

{title;A Headline} becomes :

.. raw:: html

A Headline

{title;Another Headline;1} becomes :

.. raw:: html

Another Headline

Including Macros in ReST Pages

Macros are just treated as ordinary text by docutils. That means that they must fit into the reST syntax. If they don't, then you should escape them using the raw role or the raw directive.

The Raw Role

The raw role can only be used if it is declared at the start of the document. You must include the following declaration :

.. role:: raw-html(raw)
    :format: html

From then on you can pass anything through docutils untouched, like this : :raw-html:`{small;Something to be made small}`

In the above example it's not very useful. However, macros return HTML. If you tried to include HTML in your macro - docutils would escape the < tags, and they would be included as text (or break your macro).

So {small;<em>Something to be made small</em>} doesn't work in reST documents. Try it if you don't believe me. Smile

Instead you can do :raw-html:`{small;<em>Something to be made small</em>}`, which does work.

The Raw Directive

If you use the Advanced Macros then you almost certainly want to include a passage of text to transform it. That transformation will be done after docutils has seen the text. Usually you will want the macro to transform your text verbatim - and have docutils leave it alone. In this case you need to use the raw directive.

The classic example of this is the Python source coloring macro :

.. raw:: html

    {+coloring}

    section = sections['section-name']
    pages = section['pages']

    {-coloring}

If you didn't include the raw directive, docutils would do strange things to the chunk of code - and the macro wouldn't be able to process it.

Paragraphs

Docutils treats macros as ordinary text. That means if it comes across one on its own it will treat it as a paragraph. That may not be what you intend.

For example - the {title} macro is used to create headlines. If you put this in your document on it's own, then docutils will encase it in paragraph tags. The following :

{title;Some Heading}

Produces this HTML :

<p><h3>Some Heading</h3></p>

This is neither valid, nor what you intended. The way round it, is to use the raw directive :

.. raw:: html

    {title;Some Heading}

Credits

The example macro file uses various Python modules. These are included in the modules directory that comes with the rest2web distribution. If you don't use the macros, you don't need this folder.

The various modules come from the following people and places :

  • A lot of the text in this page comes from the document Firedrop macros by Hans Nowak
  • The macros module [3] comes from Firedrop by Hans Nowak
  • The smilies use smiley.py by Mark Andrews.
  • smiley.py depends on path.py by Jason Orendorff.
  • smiley.py uses smiley sets that follow the phpbb convention, you can download alternative sets from stylesdb.
  • The smiley set included with rest2web is by a gentleman called Spider.
  • The colorize macro uses a module called colorize.py. It originated as part of the MoinMoin project. The version we use is the one from the Python Cookbook.

Footnotes

[1]And the filename must only consist of alphanumerics and the underscore character. It should start with a letter, not a number, and is case sensitive, got all that ? Question
[2]Assuming the page is in reST format of course.
[3]textmacros.py - in the rest2web folder.

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Page last modified Thu Mar 30 17:04:24 2006.


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