Developer Documentation

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If you want to see where DevAssistant development is going and you want to influence it and send your suggestions and comments, you should join our ML: We also have IRC channel #devassistant on Freenode and you can join our Google+ community.

Overall Design

DevAssistant consists of several parts:

Core of DevAssistant is written in Python. It is responsible for interpreting Yaml Assistants and it provides an API that can be used by any consumer for the interpretation.
CL Interface
CL interface allows users to interact with DevAssistant on commandline; it consumes the Core API.
(work in progress) GUI allows users to interact with Developer Assistant from GTK based GUI; it consumes the Core API.
Assistants are Yaml files with special syntax and semantics (defined in Yaml DSL Reference). They are indepent of the Core, therefore any software distribution can carry its own assistants and drop them into the directory from where DevAssistant loads them - they will be loaded on next invocation. Note, that there is also a possibility to write assistants in Python, but this is no longer supported and will be removed in near future.


Internally, each assistant is represented by instance of devassistant.yaml_assistant.YamlAssistant. Instances are constructed by DevAssistant in runtime from parsed yaml files. Each assistant can have zero or more subassistants. This effectively forms a tree-like structure. For example:

       /           \
      /             \
    Python          Ruby
    /   \            / \
   /     \          /   \
Django  Flask    Rails Sinatra

This structure is defined by filesystem hierarchy as explained in Assistants Loading Mechanism

Each assistant can optionally define arguments that it accepts (either on commandline, or from GUI). For example, you can run the leftmost path with:

$ da create python [python assistant arguments] django [django assistant arguments]

If an assistant has any subassistants, one of them must be used. E.g. in the example above, you can’t use just Python assistant, you have to choose between Django and Flask. If Django would get a subassistant, it wouldn’t be usable on its own any more, etc.

Assistant Roles

The create in the above example means, that we’re running an assistant that creates a project.

There are four assistant roles:

creator (create or crt on command line)
creates new projects
tweak (tweak or twk on command line)
works with existing projects
preparer (prepare or prep on command line)
prepares environment for development of upstream projects
extras (extras or extra on command line)
performs arbitrary tasks not related to a specific project

The main purpose of having roles is separating different types of tasks. It would be confusing to have e.g. python django assistant (that creates new project) side-by-side with eclipse assistant (that registers existing project into Eclipse).

Writing Assistants: Yaml or Scripting Languages

There are two ways to write assistants. You can either use our Yaml based DSL or write assistants in popular scripting languages (for list of supported languages see Supported Languages). This method is referred to as DevAssistant PingPong.


If you want to contribute (bug reporting, new assistants, patches for core, improving documentation, ...), please use our Github repo:

If you have DevAssistant installed (version 0.8.0 or newer), there is a fair chance that you have devassistant preparer. Just run da prepare devassistant and it will checkout our sources and do all the boring stuff that you’d have to do without DevAssistant.

If you don’t have DevAssistant installed, you can checkout the sources like this (just copy&paste this to get the job done):

git clone

You can find list of core Python dependencies in file requirements.txt. If you want to write and run tests (you should!), install dependencies from requirements-devel.txt:

pip install --user -r requirements-devel.txt

If you develop on Python 2, you’ll also need to install extra dependencies:

pip install --user -r requirements-py2.txt

Regardless of Python version, you’ll need polkit for requesting root privileges for dependency installation etc. If you want to play around with GUI, you have to install pygobject, too. To run guitest, you also need to install behave from PyPI and dogtail (not on PyPI, get it from Fedora Hosted or from your favorite package manager). (See how hard this is compared to da prepare devassistant?)