Install pip

pip is used to list, search, install, upgrade and uninstall packages from
```
PyPi, GitHub, or other VCSs
```
easy_install is a simple installer from PyPi. It comes with setuptools
setuptools has recently merged distribute, which was a fork of setuptools.
```
 this versions is Py3k compatible.
```

Both are a library to build, package and install Python projects.

Install virtualenv

virtualenv is used to isolate environments different projects, POCs and spikes, different Python versions
When Python interpreter starts it loads os and site-packages using relative paths regarding the binary location
For virtualenv it is enough to copy all this relative paths together with the binary
- It comes with pip installed
  - Install it with pip

sudo pip install virtualenv

Use virtualenv

Create a new environment:
```
virtualenv venvs/pycourse
```

Create a new environment with different Python version:

which python3.3
/usr/local/bin/python3.3
virtualenv venvs/pycourse3.3 -p /usr/local/bin/python3.3

Enable the virtualenv

echo $PATH
/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:...
source venvs/pycourse/bin/activate
echo $PATH
/Users/pev/venvs/pycourse/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:...

Disable the virtualenv:

deactivate

Use pip (inside virtualenvs)

List installed packages:

pip freeze
 wsgiref==0.1.2

Install new packages:

pip search pep8
 wsgiref==0.1.2
 autopep8                  - A tool that automatically formats Python code...
 pep8                      - Python style guide checker

pip install pep8
Downloading/unpacking pep8
 Downloading pep8-1.4.5.tar.gz (63kB): 63kB downloaded
 Running setup.py egg_info for package pep8
 ...
 Successfully installed pep8
 Cleaning up...

pip freeze
 wsgiref==0.1.2
 pep8==1.4.4

Install your project's requirements:
```
pip install -r requirements.txt
```
Create your project's requirements file:
```
pip freeze > requirements.txt
```

Use PEP8

PEP8 is the style guide for Python code
Most IDEs integrate it
Normally we accept 120 charactes per line (instead of 80)

You can run and check code style from console

pep8 --max-line-length=119 .
./file1.py:7:1: E302 expected 2 blank lines, found 1
./file1.py:9:5: E301 expected 1 blank line, found 0
./file2.py:11:5: E301 expected 1 blank line, found 0
./file2.py:13:1: W293 blank line contains whitespace



In [ ]:

    
def func(arg1, arg2=None):
    '''This is the docstring of the function, explaining what it does
    its arguments, its exceptions raised and its return value
    It may be multiline or just a single line
    '''
    pass


class MyClass(object):
    '''This is the docstring of the class, explaining what it does
    '''
    def method(self, arg1, arg2=None):
        '''This is the docstring of the method, explaining what it does
        '''
        pass



In [ ]:

    
print func.__doc__
print
print MyClass.__doc__
print
print MyClass.method.__doc__ # Even you can access docstring

Use docstrings

PEP8 defines this code documentation 'protocol'
It consists on a string block below modules, classes and functions declaration
It is possible to insert reStructuredText or EpiDoc markup
There are tools to extract, display, format and convert it:
- Sphinx, pydoc (released with the interpreter)

http://www.python.org/dev/peps/pep-0008/