Make post's date output configurable via _config.yml, closes #164

A new config variable 'date_format' is introduced in _config.yml.
It can either be set to "ordinal" to use the current format or it
can be given a string complying to strftime() format identifiers.

.themes/classic/source/_includes/post/date.html

@@ -1,10 +1,11 @@
 {% capture date %}{{ page.date }}{{ post.date }}{% endcapture %}
+{% capture date_formatted %}{{ page.date_formatted }}{{ post.date_formatted }}{% endcapture %}
 {% capture has_date %}{{ date | size }}{% endcapture %}
 {% capture updated %}{{ page.updated }}{{ post.updated }}{% endcapture %}
 {% capture was_updated %}{{ updated | size }}{% endcapture %}
 
 {% if has_date != '0' %}
-  {% capture time %}<time datetime="{{ date | datetime | date_to_xmlschema }}" pubdate {% if updated %} data-updated="true" {% endif %}>{{ date | ordinalize }}</time>{% endcapture %}
+  {% capture time %}<time datetime="{{ date | datetime | date_to_xmlschema }}" pubdate {% if updated %} data-updated="true" {% endif %}>{{ date_formatted }}</time>{% endcapture %}
 {% endif %}
 
 {% if was_updated != '0' %}

_config.yml

@@ -8,6 +8,11 @@ subtitle: A blogging framework for hackers.
 author: Your Name
 simple_search: http://google.com/search
 
+# Default date format is "ordinal" (resulting in "July 22nd 2007")
+# You can customize the format as defined in
+# http://www.ruby-doc.org/core-1.9.2/Time.html#method-i-strftime
+date_format: "ordinal"
+
 # RSS / Email (optional) subscription links (change if using something like Feedburner)
 subscribe_rss: /atom.xml
 subscribe_email:

plugins/date.rb

@@ -0,0 +1,69 @@
+module Octopress
+  module Date
+
+    # Returns a datetime if the input is a string
+    def datetime(date)
+      if date.class == String
+        date = Time.parse(date)
+      end
+      date
+    end
+
+    # Returns an ordidinal date eg July 22 2007 -> July 22nd 2007
+    def ordinalize(date)
+      date = datetime(date)
+      "#{date.strftime('%b')} #{ordinal(date.strftime('%e').to_i)}, #{date.strftime('%Y')}"
+    end
+
+    # Returns an ordinal number. 13 -> 13th, 21 -> 21st etc.
+    def ordinal(number)
+      if (11..13).include?(number.to_i % 100)
+        "#{number}<span>th</span>"
+      else
+        case number.to_i % 10
+        when 1; "#{number}<span>st</span>"
+        when 2; "#{number}<span>nd</span>"
+        when 3; "#{number}<span>rd</span>"
+        else    "#{number}<span>th</span>"
+        end
+      end
+    end
+
+  end
+end
+
+
+module Jekyll
+
+  class Post
+    include Octopress::Date
+
+    attr_accessor :date_formatted
+
+    # Convert this post into a Hash for use in Liquid templates.
+    #
+    # Returns <Hash>
+    def to_liquid
+      format = self.site.config['date_format']
+      if format.nil? || format.empty? || format == "ordinal"
+        date_formatted = ordinalize(self.date)
+      else
+        date_formatted = self.date.strftime(format)
+      end
+
+      self.data.deep_merge({
+        "title"          => self.data["title"] || self.slug.split('-').select {|w| w.capitalize! || w }.join(' '),
+        "url"            => self.url,
+        "date"           => self.date,
+        # Monkey patch
+        "date_formatted" => date_formatted,
+        "id"             => self.id,
+        "categories"     => self.categories,
+        "next"           => self.next,
+        "previous"       => self.previous,
+        "tags"           => self.tags,
+        "content"        => self.content })
+    end
+
+  end
+end

plugins/octopress_filters.rb

@@ -2,6 +2,7 @@
 require './plugins/backtick_code_block'
 require './plugins/post_filters'
 require './plugins/raw'
+require './plugins/date'
 require 'rubypants'
 
 module OctopressFilters
@@ -33,6 +34,8 @@ def post_render(post)
 
 
 module OctopressLiquidFilters
+  include Octopress::Date
+
   # Used on the blog index to split posts on the <!--more--> marker
   def excerpt(input)
     if input.index(/<!--\s*more\s*-->/i)
@@ -96,33 +99,6 @@ def titlecase(input)
     input.titlecase
   end
 
-  # Returns a datetime if the input is a string
-  def datetime(date)
-    if date.class == String
-      date = Time.parse(date)
-    end
-    date
-  end
-
-  # Returns an ordidinal date eg July 22 2007 -> July 22nd 2007
-  def ordinalize(date)
-    date = datetime(date)
-    "#{date.strftime('%b')} #{ordinal(date.strftime('%e').to_i)}, #{date.strftime('%Y')}"
-  end
-
-  # Returns an ordinal number. 13 -> 13th, 21 -> 21st etc.
-  def ordinal(number)
-    if (11..13).include?(number.to_i % 100)
-      "#{number}<span>th</span>"
-    else
-      case number.to_i % 10
-      when 1; "#{number}<span>st</span>"
-      when 2; "#{number}<span>nd</span>"
-      when 3; "#{number}<span>rd</span>"
-      else    "#{number}<span>th</span>"
-      end
-    end
-  end
 end
 Liquid::Template.register_filter OctopressLiquidFilters