Instalacja modułów Pythona
**************************

Email:
   distutils-sig@python.org

Python, jako popularny projekt open source, cieszy się aktywnym
wsparciem społeczności współtwórców i użytkowników, którzy
udostępniają tworzone przez siebie oprogramowanie innym deweloperom
Pythona w ramach licencji open source.

Dzięki temu użytkownicy Pythpa mogą efektywnie korzystać się i
współpracować korzystając z rozwiązań stworzonych wcześniej w
odpowiedzi na popularne problemy (a czasami bardzo rzadkie!), oraz
udostępniać własne rozwiązania całej społeczności.

Ta część przewodnika dotyczy procesu instalacji. O tworzeniu i
dzieleniu się własnymi projektami w Pythonie przeczytasz więcej w
Przewodniku dystrybucji.

Informacja:

  Użytkownicy związani z korporacjami i innymi instytucjami powinni
  zwrócić uwagę, że wiele organizacji ma własne zasady dotyczące
  korzystania z oprogramowania i udziału w projektach open source.
  Należy brać takie zasady pod uwagę korzystając z narzędzi
  instalacyjnych i dystrybucyjnych Pythona.


Główne pojęcia
==============

* "pip" jest preferowanym instalatorem. Od wersji Pythona 3.4 jest
  domyślnie dołączony do instalatorów binarnych.

* *Środowisko wirtualne* jest częściowo wyizolowanym środowiskiem
  Pythona instalowanym na potrzeby poszczególnych aplikacji a nie
  całego sytemu.

* "venv" jest strandardowym narzędziem do tworzenia środowisk
  wirtualnych. Jest częścią Pythona od wersji 3.3, a od 3.4 domyślnie
  instaluje "pip" we wszystkich tworzonych środowiskach wirtualnych.

* "virtualenv" to zewnętrzne (i starsze) rozwiązania alternatywne
  wobec "venv". Pozwala korzystać ze środowisk wirtualnych w wesjach
  Pythona wcześniejszych niż 3.4, które albo nie zapewniają "venv",
  albo nie są w stanie automatycznie zainstalować "pip" w tworzonych
  środowiskach.

* The Python Package Index is a public repository of open source
  licensed packages made available for use by other Python users.

* the Python Packaging Authority is the group of developers and
  documentation authors responsible for the maintenance and evolution
  of the standard packaging tools and the associated metadata and file
  format standards. They maintain a variety of tools, documentation,
  and issue trackers on both GitHub and Bitbucket.

* "distutils" is the original build and distribution system first
  added to the Python standard library in 1998. While direct use of
  "distutils" is being phased out, it still laid the foundation for
  the current packaging and distribution infrastructure, and it not
  only remains part of the standard library, but its name lives on in
  other ways (such as the name of the mailing list used to coordinate
  Python packaging standards development).

Zmienione w wersji 3.5: The use of "venv" is now recommended for
creating virtual environments.

Zobacz także:

  Python Packaging User Guide: Creating and using virtual environments


Basic usage
===========

The standard packaging tools are all designed to be used from the
command line.

The following command will install the latest version of a module and
its dependencies from the Python Package Index:

   python -m pip install SomePackage

Informacja:

  For POSIX users (including macOS and Linux users), the examples in
  this guide assume the use of a *virtual environment*.For Windows
  users, the examples in this guide assume that the option to adjust
  the system PATH environment variable was selected when installing
  Python.

It's also possible to specify an exact or minimum version directly on
the command line. When using comparator operators such as ">", "<" or
some other special character which get interpreted by shell, the
package name and the version should be enclosed within double quotes:

   python -m pip install SomePackage==1.0.4    # specific version
   python -m pip install "SomePackage>=1.0.4"  # minimum version

Normally, if a suitable module is already installed, attempting to
install it again will have no effect. Upgrading existing modules must
be requested explicitly:

   python -m pip install --upgrade SomePackage

More information and resources regarding "pip" and its capabilities
can be found in the Python Packaging User Guide.

Creation of virtual environments is done through the "venv" module.
Installing packages into an active virtual environment uses the
commands shown above.

Zobacz także:

  Python Packaging User Guide: Installing Python Distribution Packages


How do I ...?
=============

These are quick answers or links for some common tasks.


... install "pip" in versions of Python prior to Python 3.4?
------------------------------------------------------------

Python only started bundling "pip" with Python 3.4. For earlier
versions, "pip" needs to be "bootstrapped" as described in the Python
Packaging User Guide.

Zobacz także:

  Python Packaging User Guide: Requirements for Installing Packages


... install packages just for the current user?
-----------------------------------------------

Passing the "--user" option to "python -m pip install" will install a
package just for the current user, rather than for all users of the
system.


... install scientific Python packages?
---------------------------------------

A number of scientific Python packages have complex binary
dependencies, and aren't currently easy to install using "pip"
directly. At this point in time, it will often be easier for users to
install these packages by other means rather than attempting to
install them with "pip".

Zobacz także:

  Python Packaging User Guide: Installing Scientific Packages


... work with multiple versions of Python installed in parallel?
----------------------------------------------------------------

On Linux, macOS, and other POSIX systems, use the versioned Python
commands in combination with the "-m" switch to run the appropriate
copy of "pip":

   python2   -m pip install SomePackage  # default Python 2
   python2.7 -m pip install SomePackage  # specifically Python 2.7
   python3   -m pip install SomePackage  # default Python 3
   python3.4 -m pip install SomePackage  # specifically Python 3.4

Appropriately versioned "pip" commands may also be available.

On Windows, use the "py" Python launcher in combination with the "-m"
switch:

   py -2   -m pip install SomePackage  # default Python 2
   py -2.7 -m pip install SomePackage  # specifically Python 2.7
   py -3   -m pip install SomePackage  # default Python 3
   py -3.4 -m pip install SomePackage  # specifically Python 3.4


Common installation issues
==========================


Installing into the system Python on Linux
------------------------------------------

On Linux systems, a Python installation will typically be included as
part of the distribution. Installing into this Python installation
requires root access to the system, and may interfere with the
operation of the system package manager and other components of the
system if a component is unexpectedly upgraded using "pip".

On such systems, it is often better to use a virtual environment or a
per-user installation when installing packages with "pip".


Pip not installed
-----------------

It is possible that "pip" does not get installed by default. One
potential fix is:

   python -m ensurepip --default-pip

There are also additional resources for installing pip.


Installing binary extensions
----------------------------

Python has typically relied heavily on source based distribution, with
end users being expected to compile extension modules from source as
part of the installation process.

With the introduction of support for the binary "wheel" format, and
the ability to publish wheels for at least Windows and macOS through
the Python Package Index, this problem is expected to diminish over
time, as users are more regularly able to install pre-built extensions
rather than needing to build them themselves.

Some of the solutions for installing scientific software that are not
yet available as pre-built "wheel" files may also help with obtaining
other binary extensions without needing to build them locally.

Zobacz także: Python Packaging User Guide: Binary Extensions
