Skip to content


Folders and files

Last commit message
Last commit date

Latest commit



12 Commits

Repository files navigation


This is a library to aid developers in creating neat little embedded DSLs when
using python, without having to do any complex parsing or anything like that.
The resulting DSLs look a bit more like english than python does.

The idea for this was inspired by some ruby stuff that I've been using lately.
I've been using ruby quite a bit lately, and while I am still not a huge fan
of the language, I do like the idea of easy to code up DSLs. Since I wanted
a DSL for a python project I was working on, I played with a few ideas and
ended up with this. 


First, create some very basic python objects, and call the parse_dsl function
or parse_dsl_file function with the file to process, and an object that the
DSL is executed with. Here's a sample recipe DSL for baking::

	author = 'Mom'
	level = 'Easy'
	with Instructions('Yummy cookies'):
	    preheat_oven = '375F'
	    with Ingredients:
	        add += '2 1/4 cups', 'flour'
	        add += '1 tsp', 'baking soda'
	        add += '1 tsp', 'salt'
	        add += '1 cup', 'butter'
	        add += '3/4 cup', 'sugar'
	        add += '3/4 cup', 'brown sugar'
	        add += '1 tsp', 'vanilla extract'
	        add += '2', 'eggs'
	        add += '2 cups', 'chocolate chips'
	        add += '1 cup', 'nuts'
And the implementation to parse that dsl is super simple::

	import dsltool
	class Ingredients(object):
	    def __init__(self):
	        self.add = dsltool.ItemList()
	class Instructions(object):
	    preheat_oven = None
	    ingredients = Ingredients
	    steps = Steps
	    def __init__(self, name): = name
	class Recipe(object):
	    author = None
	    level = None
	    def __init__(self):
	        self.instructions = Instructions
	if __name__ == '__main__':
	    obj = dsltool.parse_dsl_file('cookies.pydsl', Recipe)

There is a working example in the 'examples' directory. Check it out.


No idea. I'm sure it's not that bad. I imagine typical usage of a DSL
isn't going to be in a performance-dependent part of your application


If the user writes the DSL incorrectly, there are lots of possible gotchas. 
If enough people use this thing and file bug reports, together we can
remove many of them. I'll try to list them as I find them.

Do not expect 0.1.x releases to have a stable API. I'm still exploring the
possibilities of this, so as better ways to do things emerge newer releases
will have those instead. 


Uses py.test for testing. Still need better tests, but it catches a lot 
of common mistakes I've made so far. ;)


It's all on github, so file your bug reports there. If you have a patch, 
the best way to do it is just create a fork and send me a pull request. 
If you don't include a test case for your patch (these are really easy to
create!), then it probably won't be accepted.


Author:: Dustin Spicuzza (


A ruby-inspired python library to enable making simple domain specific languages







No packages published