Hosts the meeting notes for the beginning coder (Python-based) meetup for Women Who Code ATX
A Primer for Women Who Code ATX
First, a module in Python is a collection of functions (or methods, if you want to get fancy), variable definitions, and classes. As noted in the Python Packaging docs, it’s a “basic unit of code reusability” for Python. Packages are collections of Python modules and other files that collectively make up a released bit of software. You can think of them as Python building blocks.
When getting started with pip, you’re actually going to install it with easy_install. Pip is a package itself. If you have Python 2.7.9 or greater or Python 3.4 or greater, you already have pip. Congratulations!
If you have an older version of Python (and you can’t upgrade… you should try to upgrade first if you can), you’ll need to install it. To get it, you can invoke easy_install, one of the setup tools bundled with Python, from your command line like this:
easy_install pip
You may have to use sudo to install pip (sudo easy_install pip), but pip
should be the only package you ever use sudo to install with Python. See the
next section for the reason why.
You can also install it with your local package manager most of the time, or you can download it and install it. Follow the directions at https://pip.pypi.org/en/latest/installing/ if you’re unsure.
There’s a few differences, actually. First, understand that pip is the standard, and no one really uses easy_install any longer. Pip showed up four years or so after easy_install, so there are some things that it was designed for that people saw as flaws with easy_install.
Easy_install takes an egg, or a boxed up version of a package that can be either unzipped and installed or run directly in the interpreter, as input. Pip, on the other hand, takes a wheel, or a zipped package with metadata attached, as input. Both of them use setuptools under the hood in one form or another to take those inputs and install them.
Pip has one great thing going for it: the ability to install from a requirements file. Using a requirements file allows developers to ensure a program will run on different systems because they can tell the system exactly what the program needs to run on. Sometimes new releases of different packages can cause breaking changes–changes that prevent a system from running,–which can cause havoc in production systems.
The big things to know is that eggs are slowly being replaced completely by wheels and that wheels are the current standard. If you want to learn more about wheels, check out PEP (Python Enhancement Proposal) 427.
If you want to see a full rundown of the differences, check out this list.
Never ever use sudo with pip. You will corrupt your Python installation on your machine. It’s much better to use virtual environments (for example, with the packages virtualenv or virtualenvwrapper. I prefer the latter.), which is a later topic.
Need to install something but don’t have admin access? You can install it locally just for you. run
pip install --user <package-name>
You have a couple options to look up packages with pip.
Using the command line is probably the way most programmers look up packages available with the pip command. Simply use the following syntax:
pip search <keyword>
Replace <keyword> with the package name, and you’re off searching through the
index.
You can also go explore the packages available to you through pip on the Python Package Index, which is often just abbreviated as PyPI.