The Blockly project from https://code.google.com/p/blockly/ is a visual programming language aiming to be easy for beginners to learn programming...

The programming environment runs in the browser, it saves the program in an XML format, compiles (or generates) to Javascript, Dart, Python.... it uses so called generators to make the translation.

blockly2ruby implements generators for the Ruby programming language.

I wrote the code and tested in a version of April 2014. I do not plan to maintain the code anymore.

One problem I faced is that the generated code tries to produce the same result as Blockly while the Blockly philosophy (https://code.google.com/p/blockly/wiki/Language) is that the produced code should be easy to read and follow the target language aspects... contradictory somehow.

The code contains next parts (folders):

• generators: the Javscript scripts generating Ruby
• test: tests to validate the generators and Javascript scripts generating Blockly unit tests
• ruby_tester: Ruby code that run the generated tests
• compiler: Javascript scirpts that allow to compile from XML to Ruby from command line (using https://phantomjs.org/)
• compiler.sh; shell script runnning the Javscript compiler from the command line
• server.rb: a Ruby script that runs a server to run Blocky on a local box

Next sections give more information about the different parts.

The generators were based on the Python generators, they are compatible with the April's version. I wrote two versions of the generators because they changed during several months, as I do not intend working on this code anymore do not expect to make it work with recent versions of Blocky.

The idea I had when I wrote the generators was to write test cases in pure Blockly with comments containing the expected output. The generated code is used by the ruby_tester scripts to validate the generated code.

Example of generated code:

# expects '#ff0000'
blockly_puts('#ff0000')

ruby_tester detects the special comment (*# expects *) and tests that the line blockly_puts('#ff0000') produces the expected results.

Other special comments include:

• # expects true, boolean expectation
• # expects 1, number expectation
• # expects "hello", string expectation
• # expects sequence "a","b","c", sequence expecation
• # expects 3 times "repeat", expecting repeated n times

The Javascript for the Blocky unit tests generator comes in two flavours:

• unittest_ruby_normal.js: producing code being a straight mapping from Blockly logic to Ruby code
• unittest_ruby_unit.js: producing code integrating with Ruby's unit test framework

The actual generator script is unittest_ruby.js and is a symbolic link to one of the above scripts.

Two shell scripts create the symbolic links to enable one of them (set_normal and set_unit).

The Blockly unit-tests locate in its tests/generator directory, change the index.html file to enable Ruby generators. Add next lines:

<script type="text/javascript" src="unittest_ruby.js"></script>
<script type="text/javascript" src="../../generators/ruby/logic.js"></script>
<script type="text/javascript" src="../../generators/ruby/loops.js"></script>
<script type="text/javascript" src="../../generators/ruby/math.js"></script>
<script type="text/javascript" src="../../generators/ruby/text.js"></script>
<script type="text/javascript" src="../../generators/ruby/lists.js"></script>
<script type="text/javascript" src="../../generators/ruby/colour.js"></script>
<script type="text/javascript" src="../../generators/ruby/variables.js"></script>
<script type="text/javascript" src="../../generators/ruby/procedures.js"></script>

And copy the Ruby generators files in the <blockly-root>/generators/ruby

• Jean Lazarou