Executing arbitrary blocks of python code with RubyPython

Question

I'm trying to use the RubyPython module (https://github.com/halostatue/rubypython) to execute Python code from within a Ruby script. I have the module all set up correctly, but am very confused how to use it.

If I had a block of Python code as text, say:

def multiply(x, y):
    return x * y * y

z = multiply(x, y)

How would I be able to pass this to Python to execute with 'x' and 'y' defined dynamically in Ruby, and then be able to retrieve the value of 'z'?

Edit per comment request So far, this works and makes sense to me:

RubyPython.start(python_exe: "/usr/bin/python2.6")
cPickle = RubyPython.import("cPickle")
p cPickle.dumps("Testing RubyPython.").rubify
RubyPython.stop # stop the Python interpreter

That gives me an output of "S'Testing RubyPython.'\n."

And I can run very simple commands like this:

RubyPython.start(python_exe: "/usr/bin/python2.6")
x = 3
y = x * x * x
print "y = %d" % y
RubyPython.stop # stop the Python interpreter

That gives me an output of "y = 27", as expected.

But once I try to define a method in python, I just get a series of errors:

RubyPython.start(python_exe: "/usr/bin/python2.6")
def my_multiply(x, y):
  return x * y * y
z = my_multiply(2, 3)
print "z = %d" % z
RubyPython.stop # stop the Python interpreter

I get syntax error, unexpected ':'

So how would I execute this block of python code using this module? And more importantly, how would I pass values in from Ruby into the Python code that is executing?

Can you show _what you did_ when you followed the advice in https://github.com/halostatue/rubypython (Synopsis, Basic Usage, Specific Python Version, etc.) ? Therein are quite a few examples that should lead you in the right direction. — boardrider, May 18 '15 at 08:48
Is it just me, or are you entering Python code where the Ruby interpreter is expecting Ruby code. Your error "syntax error, unexepected ':'" seems to agree with my basis. I don't see any examples of RubyPython where it works that way - you should be doing that as a string and passing it to RubyPython in some way I would imagine. **edit** The first example you list (where you're printing with Python formatting style) is perfectly valid and legal Ruby - thus it works. The `:` is out of place in the second example and the Ruby interpreter is complaining. — Brandon Buck, May 18 '15 at 15:09
Brandon - my hypothesis is the same as yours. I just can't figure out how I would pass that code as a string to RubyPython - that's the crux of my question! — Bryce, May 18 '15 at 15:16
I see now, I was looking into it myself but see nothing as well. It looks like it just enable you to import and call Python modules if I understand the docs correctly. I'll keep digging. — Brandon Buck, May 18 '15 at 15:19

Brandon Buck · Accepted Answer · 2015-05-26T14:10:30.397

Since no answer has been made, and I managed to find something (although a very ugly something at that).

I'm not sure at all if this is the intended method to use RubyPython but I was able to get things to function by doing the following set of tasks:

 > RubyPython.start
 > RubyPython::Python.PyRun_SimpleString <<-PYTHON
*> def test():
*>     print("Hello, World")
*> PYTHON
 > main = RubyPython.import("__main__")
 > main.test()
 >>> Hello, World!
 > RubyPython::Python.PyRun_SimpleString <<-PYTHON
*> def my_mult(x, y):
*>     return x * y
*> PYTHON
 > main.my_mult(10, 20).rubify
 >>> 200

Again, whether this is the "correct" way to do it, or not is up for debate - but it worked.

Executing arbitrary blocks of python code with RubyPython

1 Answers1