The OCRA Compiler: Tips, Tricks, and Gotchas

I've previously mentioned Lars Christensen's One-Click Ruby Application Builder, a "compiler" for Ruby scripts that shows a lot of potential (and current value). There's not much documentation yet, but folks are installing it, using it, and providing feedback. It works right out of the box for many purposes, but here are a few things to keep in mind as you use it...

"Failed to create directory" Error

One user reported receiving the error "Failed to create directory" when running the compiled executable. As a possible workaround, try running ocra.rb from the directory where your script is located. For example, instead of running...

ocra.rb "C:\code\rubyscripts\application.rbw"

...navigate to the "C:\code\rubyscripts" directory, then run:

ocra.rb application.rbw

Note that while this resolved the problem on my machine, it didn't help the person who originally reported the problem.

Require RubyGems

When you compile your script (which uses one or more gems) with OCRA and then run the executable, you may receive a 'no such file to load' error. Try adding the line...

require 'rubygems'

...to the top of your script, above the other require statements. I've found that a script that runs pre-compiled without this statement may not execute once compiled.

Compile Without Running

I mentioned earlier that it would be nice to have an option to avoid fully running the script, similar to RubyScript2Exe's exit if RUBYSCRIPT2EXE.is_compiling? idiom. A tip of the hat goes to reader "BackOrder", who offered the following solution:

exit if Object.const_defined?(:Ocra)

Put all your require statements at the top of your code, followed by this line.

OCRA and Mechanize: "libxml2.dll not found"

There may be a problem compiling a script that requires the mechanize gem. Running the compiled executable resulted in a "libxml2.dll was not found" error on my machine.

Note that the above observations relate to version 1.0.2 (current as of this writing) of the ocra gem.

More information is available in the OCRA forums and bug tracker.

Thanks again to Lars for creating OCRA, and to the users who have installed it, used it, and provided their feedback.

Thanks for stopping by!

Handling WIN32OLE Events in Excel

Someone recently asked how to have Ruby react to events in Excel. Specifically, they were trying retrieve the contents of a row in a worksheet when it's selected.

The win32ole module provides a WIN32OLE_EVENT class that will allow you to execute a block of code when a specific event occurs.

To set the scene, let's use the WIN32OLE.connect() method to connect to an existing instance of Microsoft Excel and grab a reference to the currently active workbook:

require 'win32ole'
xl = WIN32OLE.connect('Excel.Application')
wb = xl.ActiveWorkbook

Next, we'll call the WIN32OLE_EVENT.new() method to create a new OLE event object. You pass this method an OLE object---our Workbook object---and the name of the event sink. In this instance, we want to use the WorkbookEvents sink:

ev = WIN32OLE_EVENT.new(wb, 'WorkbookEvents')

Once you have your event sink defined, you call its on_event() method to hook into a particular event and run a block of code when that event fires. In our scenario, we want to take action when the SheetSelectionChange event fires.

ev.on_event('SheetSelectionChange') do
    range = xl.Selection
    puts(range.Value)
    STDOUT.flush()
end

The above block of code will execute when the user selects a range of cells, and will print out the array of values from the selected cells.

Finally, you need to start the event message loop to begin the event monitoring:

loop do
    WIN32OLE_EVENT.message_loop
end

In the real world, we need a means to exit the message loop. Let's catch the BeforeClose event, which fires (of course) just prior to the workbook being closed:

ev.on_event('BeforeClose') do
    exit_event_loop
end

Now, when the BeforeClose event fires, we'll have it call a new exit_event_loop() method, which sets a $LOOP value to false:

$LOOP = true

def exit_event_loop
    $LOOP = false
end

Finally, we'll modify our earlier message loop block, accordingly, and also toss in a brief pause:

while $LOOP
    WIN32OLE_EVENT.message_loop
    sleep(0.1)
end

Our complete code looks something like this:

require 'win32ole'

xl = WIN32OLE.connect('Excel.Application')
wb = xl.ActiveWorkbook

ev = WIN32OLE_EVENT.new(wb, 'WorkbookEvents')

ev.on_event('SheetSelectionChange') do
    range = xl.Selection
    puts(range.Value)
    STDOUT.flush()
end

ev.on_event('BeforeClose') do
    puts('Closed');STDOUT.flush
    exit_event_loop
end

$LOOP = true

def exit_event_loop
    $LOOP = false
end

while $LOOP
    WIN32OLE_EVENT.message_loop
    sleep(0.1)
end

And there you have it. Tweak to suit your individual needs.

Thanks for stopping by!

OCRA: One-Click Ruby Application Builder

I recently mentioned the fact that RubyScript2Exe 0.5.3 doesn't play well with recent versions of RubyGems. At the end of that post I mentioned that there are alternatives emerging for creating executables from your Ruby code, including Lars Christensen's OCRA, the One-Click Ruby Application Builder.

I've had a chance to take OCRA for a short test drive and it looks promising. Like Erik Veenstra's RubyScript2Exe, OCRA lets you "compile" your ruby code into an EXE file that you can distribute to others, without requiring that the users have Ruby installed on their PCs. To quote the OCRA page:

The executable is a self-extracting, self-running executable that contains the Ruby interpreter, your source code and any additionally needed ruby libraries or DLL.

OCRA can be installed via RubyGems: open a console window and type:

gem install ocra

It's also available from the RubyForge page. Version 1.0.2 is the latest as of this writing.

The syntax to compile a script is...

ocra.rb [option] your/script.rb

...where option is one or more of the following:

--dll dllname    Include additional DLLs from the Ruby bindir.
--no-lzma        Disable LZMA compression of the executable.
--quiet          Suppress output.
--help           Display this information.
--windows        Force Windows application (rubyw.exe)
--console        Force console application (ruby.exe)
--no-autoload    Don't load/include script.rb's autoloads

Thus far, I have exercised only the --windows and --console options.

To create a non-console application, either use the --windows option or give your script the .rbw filename extension. Compiling a basic non-console script is as simple as opening a console window, navigating to the folder containing your script, and typing:

ocra.rb myscript.rbw

OCRA will then run your script to check for dependencies, gather the necessary files, and create your executable. An option to avoid fully running the script would be nice, similar to RubyScript2Exe's exit if RUBYSCRIPT2EXE.is_compiling? idiom.

OCRA uses LZMA compression, so the resulting executable is relatively small. A simple wxRuby app, for example, resulted in a 2.5 Mb executable. The same app compiled with RubyScript2Exe weighed in at over 9 Mb. Apps that do not require a GUI toolkit will be even smaller, perhaps 500k.

I haven't spent a lot of time with OCRA yet, but I think it shows great potential and I want to thank Lars Christensen for his efforts. If you have a need to distribute Ruby programs to non-technical users, you should check it out and pass your feedback along to Lars.

Thanks for stopping by!

Ruby & Excel: Extracting Cell Comments

Someone recently asked how to get the comment text from a particular cell in an Excel worksheet.

You could call the cell's Comment property to obtain a reference to the Comment object, then use the Comment object's Text property to get---or set---the text of the comment.

Imagine that you have a workbook open and you want to get the comment text from cell B2 in the currently selected worksheet. The following code should do the trick:

require 'win32ole'

xl = WIN32OLE.connect('Excel.Application')
ws = xl.ActiveSheet
cell = ws.Range('B2')
comment = cell.Comment
text = comment.Text

Do you---or would you like to---use comments in your worksheets? I can go into further detail about the Comment object and the Comments collection, but that's all we have time for today.

Thanks for stopping by!

RubyScript2Exe and RubyGems

I've written here previously about Erik Veenstra's RubyScript2Exe "compiler". I use it frequently to create standalone EXE files on Windows.

If you use RubyScript2Exe, you should note that the current version (0.5.3) doesn't appear to play well with the new version (1.3.2) of Rubygems released a few weeks ago. Attempting to compile a script results in the error:

    undefined method `list' for Gem::Specification:Class

Some additional discussion can be found in this Ruby Forum thread.

Perhaps Erik will update RubyScript2Exe to utilize the Gem.loaded_specs method, as suggested by Eric Hodel.

In the meantime, RubyGems 1.3.1 continues to work well for me with RubyScript2Exe. Be aware, however, that Daniel Berger points out in the above thread that version 1.3.2 addresses a couple issues related to the win32-file library.

There are alternatives emerging for creating executables from your Ruby code, including ocra and crate. I haven't had the opportunity to try either of these yet, but plan to in the near future. If you have experience with these or similar tools, feel free to share your comments here. Thanks!