simpleblog 0.9.6

Description:

simpleblog 0.9.6

Simpleblog is a simple Python blogging system. I use it to write
and publish my own blog at http://blog.peterdonis.com. I wrote
it because I couldn’t find an existing blogging system that made
it sufficiently easy to write, format, and publish my blog.
My chief goal with simpleblog is for the system to stay out
of my way; I want to be able to add features easily, but other
than when I’m actually doing that, I want simpleblog to “just
work”, so I don’t even have to think about it at all. That way
I can think about what I’m writing instead. With the existing
systems I’ve tried, I have ended up spending too much time
figuring out the internals of the system in order to get things
the way I want them. Admittedly, I have not tried many existing
systems; but what I have read about the ones I haven’t tried
has not encouraged me that any of them would work any better
for me. So here we are.
If you just want to start using simpleblog, without digging
into its internal details, then once you’ve installed it, you can
copy the contents of one of the example blogs to a directory of
your choice, and start writing your blog there. The layout of
the example blogs, and the files in them, will give you a start.
Before writing any entries, you will want to at least edit the
blog.json or blog.yaml file to customize your blog’s
metadata, and the template files in the templates
subdirectory, which give extremely plain HTML pages by default.
Note that in order to use simpleblog, you will need to have
installed plib.stdlib (my library of useful Python stuff,
which is used in a number of places in simpleblog). It is
available at http://pypi.org/project/plib.stdlib. If you
want to use YAML instead of JSON for your config and blog
metadata files (I certainly find YAML much easier to type since
I hate typing delimiters, as you will know if you read my blog),
you will also need to have installed PyYAML, the YAML parsing
library for Python (which in my opinion should be in the Python
standard library).
Note: simpleblog works with Python 2. If you are using Python
3, see https://pypi.org/project/simpleblog3.

Simpleblog’s Architecture
The structure of simpleblog is simple (no, that wasn’t intended
to be humor, it’s just the way it naturally came out). There
are five core object types: the config, the blog, pages, containers,
and entries. The config lets you define or customize the internal
behavior of the code, and all the other objects have a reference
to it. The other object types fall into a simple hierarchy:

The blog contains one or more pages, plus metadata which can be
specified in a separate file from the config file; the default
filenames are blog.yaml (or blog.json) and config.yaml
(or config.json), but other filenames can be passed on the
command line to the simpleblog-run script–see below;
Each page wraps a “source”, which can be either a single entry,
or a container;
A container contains one or more entries that have something in
common;
An entry is the actual content.

It’s important to note that the above is all that the core
objects implement, and it is completely general. Everything
specific, such as what actual “sources” there are, which entries
are in which containers, etc., is all defined in extensions.
(Strictly speaking, there is one default container in every blog,
which simply contains all its entries, and every blog has an
index page, which uses that container as its “source”, plus a
page for every individual entry. But that’s all that is in
the blog by default. Of course, that by itself is enough to
have a simple blog, which is part of the point.)

Templates
Simpleblog uses Python’s built-in string templating and formatting
to render entries and pages. The example blogs illustrate the
basics of how this works. This is one area where I do not have
any items on my To Do list; the various fancy templating engines
out there have their uses for highly dynamic web applications,
but for a simple blog they are, in my opinion, extreme overkill.
But the extension mechanism is there for anyone who disagrees
and wants to use their favorite templating engine.


Extensions
Extensions allow pretty much every behavior of the four blog
object types–everything above except the config–to be changed,
and even allow new behaviors to be added. (I say “pretty much”
only because I can’t be absolutely positive I have allowed for
every possibility; but that’s my goal.) This is done with a
simple (yes, you’ll see that word cropping up a lot…) but
powerful mechanism. You write a Python module that contains a
subclass of the BlogExtension class, and implements your
desired changed or added behaviors, and add its name to the
list of extensions in your config file. That’s it. Or, of
course, you can use one of the extensions that come with
simpleblog, listed below. I use all of them for my blog. They
give good examples of how the extension mechanism can be used.
(Note: Strictly speaking, since extension names will be looked
up as Python module names, they must be valid identifiers,
which means they can’t include hyphens. However, simpleblog
allows you to use hyphens when referring to extensions, as in
the render-markdown extension; it converts the hyphens to
underscores before looking up the module name. Command names
are handled the same way–see below.)

The archives extension adds containers for entries that
were published during specific time periods–years, months,
and/or days, depending on the config settings–and adds
archive pages to the blog for each container.
The categories extension allows you to classify entries
by category, and adds a container and an index page for each
category.
The copyright extension automatically generates copyright
metadata based on the starting and ending year of blog entries.
The feed extension generates feeds for your blog’s index
page. Both RSS 2.0 and Atom feeds are supported. This extension
also supports archived feeds per RFC 5005 (this only works for
Atom feeds since the RSS spec does not appear to support
this), which lets you limit the size of your syndication
feed file by archiving old entries.
The folding extension allows your entries to have “short”
versions that can appear in index pages, with links to the
entry page that shows the entire entry (including the part
“below the fold”).
The grouping extension allows entries on index pages to
be grouped, so that group headers and footers can appear in
addition to the entries themselves. The default is to group
by date, which goes along with the default sorting of entries
in all containers, which is reverse chronological; but these
can be changed by config settings (of course they should both
be changed consistently).
The indexes extension adds index pages to your blog that
give links to all entries in either alphabetical (by title),
chronological, or “key” (meaning the unique key assigned to
each entry) order.
The links extension allows you to add links to the previous
and next entries in your blog’s containers to each entry. By
default it only does this on single-entry pages, but this can
be configured; also, which links actually appear on the page
is controlled by a template you provide.
The localize extension is currently experimental; all it
does is add a “locale” config setting if certain other config
settings are present. More localization functionality is
on the To Do list; currently simpleblog is only tested with
English ASCII text.
The paginate extension allows splitting sources with many
entries into multiple pages.
The quote extension adds quoted versions of all URLS
found in the blog’s metadata. I added this because I link to
the W3C HTML validator for my blog’s index page, which wants
quoted URLs, and this was an easy way to avoid having to type
them into my blog metadata by hand. :)
The render-markdown extension allows your entry source
to be plain text using Markdown syntax; the extension then
renders it into HTML. (Without any extension changing the
rendering, simpleblog just uses your entry source unchanged
as its rendered HTML.) There are config options to specify
the output format for Markdown (the default is HTML 4) and
to “pretty print” the output.
The tags extension allows you to add tags to your entries,
and adds a container and index page for each tag. This extension
uses the caching mechanism for entry metadata (see below).
The timestamps extension uses the caching mechanism to
store immutable file timestamps. (Without any extension, an
entry’s timestamp is the last modified time of its source
file, but this means if you make any change at all to an entry
once it is published, its time stamp changes, which may change
where it appears in index pages.)
The timezone extension makes entry timestamps timezone-aware
(without this extension they are “naive” datetime objects).
The timezone_name config setting lets you explicitly declare
your blog’s timezone; otherwise your system’s local time zone
setting will be used (note, however, that the utc_timestamps
config setting can force the timezone to UTC; see notes in the
change log). This extension requires the pytz library.
The title extension allows you to specify a title for each
entry in the entry’s source file. (Without any extension, the
title of an entry is the same as its relative file name or URL
path, which is probably not what you want.) It also supports
very simple italics and bold formatting in the title.

Note that in some cases the order in which extensions are declared
in your config file matters. The order in which extensions are
listed in the config determines the order in which they are loaded,
which determines the order in which they get to process whatever
data they are processing, which can obviously make a difference
if multiple extensions process the same data. The cases you are
most likely to encounter are extensions that process the raw
entry source data (the title, tags, and folding
extensions all do, and the ordering that is known to work is the
order in which I just gave them), and extensions that add sources
in the form of new containers (the archives, categories,
and tags extensions) vs. extensions that need to know all the
containers in the blog (the links extension is the key one,
and needs to be loaded after the ones listed just now).


Entry Metadata Caching
Entry metadata is often useful for putting entries into containers
and ordering them properly. It is nice to be able to do this without
having to actually ask the filesystem for any data on individual
entries, by either statting or opening and reading the entry source
files. Simpleblog provides a caching mechanism for entry metadata
to make this simple. Just use the cached decorator on any
property that represents metadata you want cached, and provide the
name of the file the cache should be stored in.


Commands
All of the above is nice, but in order to actually use it, you have
to have some kind of front end. The simpleblog-run script provides
one. If run without any command at all, the script simply puts you
into the Python interactive shell, with the simpleblog package
loaded; I find this extremely useful for testing and debugging. But
the script can also be enhanced with commands, by a mechanism similar
to the extension mechanism.
(Note: As with extension names, hyphens in command names are converted
to underscores before looking up the module, so you can use hyphens,
as is done below, if you find them easier to type, as I do.)

The publish command publishes your statically rendered blog via
SSH to a remote host that will serve it. By default it uses the
rsync command, but a config setting allows you to change the
command name (though it must be a command that uses the same
command-line syntax as rsync, such as scp). You can also
configure the command options and the SSH user, the remote hostname,
and the path on the remote host to publish to.
The render-static command renders static versions of all the
pages in your blog. A config setting controls the directory that
the files are rendered to. For my blog, this is currently sufficient,
since I publish it as static files.
The serve-local command serves your statically rendered blog on
localhost for testing. You can use command-line options to change
the host name (or IP address) and port used (the defaults are
localhost on port 8000), for example to allow testing on a LAN.
Since the built-in Python SimpleHTTPServer is used, it is not
recommended to try to serve your blog to the Internet using this
command.

For quick help on usage, use the --help option to the simpleblog-run
script. If a command name is provided, help specific to that command will
be shown; otherwise, general help will be shown.


User-Defined Commands and Extensions
Simpleblog supports defining your own commands or extensions,
separate from the ones supplied with simpleblog itself. All you
have to do is set the command_dir or extension_dir config
and supply Python modules that match the command or extension name
you want to use. The command and extension loading mechanism will
look in your user-defined directories first, so you can even define a
command or extension with the same name as a pre-packaged one, and it
will take precedence.



To Do
Add fancier example blogs to show how the various extensions work.
Add documentation other than this README file, both for users and
for developers.
Add support for comments while still allowing the blog to be
statically generated.