evennia/CODING_STYLE.md

# Evennia Code Style

All code submitted or committed to the Evennia project should aim to
follow the guidelines outlined in [Python PEP 8][pep8]. Keeping the code style
uniform makes it much easier for people to collaborate and read the
code.

A good way to check if your code follows PEP8 is to use the [PEP8 tool][pep8tool]
on your sources.

## A quick list of code style points

 * 4-space indendation, NO TABS!
 * Unix line endings.
 * CamelCase is only used for classes, nothing else.
 * All non-global variable names and all function names are to be
   lowercase, words separated by underscores. Variable names should
   always be more than two letters long.
 * Module-level global variables (only) are to be in CAPITAL letters.
 * (Evennia-specific): Imports should normally be done in this order:
   - Python modules (builtins and standard library)
   - Twisted modules
   - Django modules
   - Evennia src/ modules
   - Evennia game/ modules
   - Evennia 'ev' API imports
 * All modules, classes, functions and modules should have doc
   strings formatted as described below

## Doc strings

All modules, classes, functions and methods should have docstrings
formatted with [Google style][googlestyle] -inspired indents, using
[Markdown][githubmarkdown] formatting where needed. Evennia's `api2md`
parser will use this to create pretty API documentation.

> Note that far from all sources are currently formatted using the
> consistent style listed here. This is something that is being
> worked on and any help to convert existing docs are appreciated.
> We also don't support all forms of the google style syntax, going
> for a limited and more restricted set for consistency.

### Module docstrings

Modules should all start with at least a few lines of docstring at
their top describing the contents and purpose of the module.
Sectioning should not be used - the auto-api will create this
automatically. Otherwise markdown should be used as needed to format
the text.

Example of module docstring (top of file):

```python
"""
This module handles the creation of `Objects` that
are useful in the game ...

"""
```

Code examples should use [multi-line syntax highlighting][markdown-hilight]
to mark multi-line code blocks, using the "python" identifier. Just
indenting code blocks (common in markdown) will not produce the
desired look.

When using any code tags (inline or blocks) it's recommended that you
don't let the code extend wider than about 70 characters or it will
need to be scrolled horizontally in the wiki (this does not affect any
other text, only code).

### Class docstrings

The root class docstring should describe the over-arcing use of the
class. It should usually not describe the exact call sequence nor list
important methods, this tends to be hard to keep updated as the API
develops.

Example of class docstring:

```python
class MyClass(object):
    """"
    This class describes the creation of `Objects`. It is useful
    in many situations, such as ...

    """
```

### Function / method docstrings

Example of function or method docstring:

```python

def funcname(a, b, c, d=False, **kwargs):
    """
    This is a brief introduction to the function/class/method

    Args:
        a (str): This is a string argument that we can talk about
            over multiple lines.
        b (int or str): Another argument
        c (list): A list argument
        d (bool, optional): An optional keyword argument

    Kwargs:
        test (list): A test keyword

    Returns:
        e (str): The result of the function

    Raises:
        RuntimeException: If there is a critical error,
            this is raised.
        IOError: This is only raised if there is a
            problem with the database.

    Notes:
        This is an example function. If `d=True`, something
        amazing will happen.

    """
```

The syntax is very "loose" but the indentation matters. That is, you
should end the block headers (like `Args:`) with a line break followed
an indent. When you need to break a line you should start the next line
with another indent. For consistency with the code we recommend all
indents to be 4 spaces wide (no tabs!).

Here are all the supported block headers:

```
    Args/Arg/Kwargs/Kwarg:
        argname (freeform type): text
        or
        freeform text
    Returns/Yields:
        kwargname (freeform type): text
        or
        freeform text
    Raises:
        Exceptiontype: text
        or
        freeform text
    Notes/Note/Examples/Example:
        freeform text
```

Parts marked with "freeform" means that you can in principle put any
text there using any formatting except for the indentation to mark
which block you are part of. You should normally use the specified
format rather than the freeform counterpart (this will produce nicer
output) but in some cases the freeform may produce a more compact and
readable result (such as when describing an `*args` or `**kwargs`
statement in general terms). The first `self` argument of class methods
should never be documented. 

Note that

```
Args:
    argname (type, optional): text
```

and

```
Kwargs:
   argname (type): text
```

mean the same thing! Which one is used depends on the function or
method documented, but there are no hard rules; If there is a large
`**kwargs` block in the function, using the `Kwargs:` block may be a
good idea, for a small number of arguments though, just using `Args:`
and marking keywords as `optional` will shorten the docstring and make
it easier to read.


## Ask Questions!

If any of the rules outlined in PEP 8 or in the sections above doesn't
make sense, please don't hesitate to ask on the Evennia mailing list
or in the chat.


[pep8]: http://www.python.org/dev/peps/pep-0008
[pep8tool]: https://pypi.python.org/pypi/pep8
[googlestyle]: http://google-styleguide.googlecode.com/svn/trunk/pyguide.html?showone=Comments#Comments
[githubmarkdown]: https://help.github.com/articles/github-flavored-markdown/
[markdown-hilight]: https://help.github.com/articles/github-flavored-markdown/#syntax-highlighting