eRuby
From Wikipedia, the free encyclopedia
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| Latest release | 1.0.5 / 2004-12-14 |
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| Written in | Ruby |
| Operating system | Cross-platform |
| Development status | Active |
| Type | template engine |
| License | GPL and LGPL |
| Website | http://www.modruby.net/en/index.rbx/eruby/whatis.html |
eRuby is a templating system that embeds Ruby into a text document. It is often used to embed Ruby code in an HTML document, similar to ASP, JSP and PHP.
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[edit] Usage
eRuby allows Ruby code to be embedded within a pair of <% and %> delimiters. These embedded code blocks are then evaluated in-place (they are replaced by the result of their evaluation).
Here are a few examples of eRuby usage:
One line of Ruby
<% ruby code %>
Output like hello from <% print "hello" %> would replace the ruby code between the delimiters.
Alternatively, lines starting with a % sign are interpreted as Ruby as well:
% ruby code
Multiple lines
These can appear less graceful because the beginning and ending are not quite the same. They function like blocks in Ruby and are terminated by <% end %>. They are commonly used as looping constructs, which appear like this:
<ul> <% 3.times do %> <li>list item</li> <% end %> </ul>
Outputting:
- list item
- list item
- list item
The same code could also be written as:
<ul> % 3.times do <li>list item</li> % end </ul>
Expression result substitution
<%= ruby expression %>
- Value evaluated from expression like 11 from 7 + 4 would replace the ruby expression between the delimiters. Often these are only one line.
Comments
<%# ruby code %>
- this is the same as a comment in Ruby. All Ruby code after the # is ignored and generates nothing. Other things common in eRuby are simply common in Ruby, such as string substitution with
#{string_name}
, which is similar in languages such as Perl or PHP.
[edit] Implementations
There are several implementations of eRuby:
[edit] eruby
eruby is an implementation of eRuby written in the C programming language.
[edit] erb
erb is an implementation of eRuby, written purely in the Ruby programming language.
[edit] erubis
erubis is an implementation of eRuby implemented in Ruby and also in Java. It runs faster than eruby and erb,[citation needed] and has several useful options, including alternate tags allowing for valid XML.
[edit] See also
[edit] External links
- eruby source Download (from www.modruby.net)
- "Ruby and the web", a chapter from "The Pragmatic Programmer's Guide"
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