This package will install Python $FULL_VERSION for Mac OS X $MACOSX_DEPLOYMENT_TARGET for the following architecture(s): $ARCHITECTURES.

NOTE:  This is an early developer preview of the next feature release of Python 3.  Many features are yet to be added and existing features may change substantially or be deleted prior to the feature code freeze.

Certificate verification and OpenSSL

This variant of Python 3.7 includes its own private copy of OpenSSL 1.0.2.  The deprecated Apple-supplied OpenSSL libraries are no longer used.  This means that the trust certificates in system and user keychains managed by the Keychain Access application and the security command line utility are no longer used as defaults by the Python ssl module.  For this preview release, a sample command script is included in /Applications/Python 3.7 to install a curated bundle of default root certificates from the third-party certifi package (https://pypi.python.org/pypi/certifi).  If you choose to use certifi, you should consider subscribing to the project's email update service to be notified when the certificate bundle is updated.

The bundled pip included with this installer has its own default certificate store for verifying download connections.

Update your version of Tcl/Tk to use IDLE or other Tk applications

To use IDLE or other programs that use the Tkinter graphical user interface toolkit, you need to install a newer third-party version of the Tcl/Tk frameworks.  Visit https://www.python.org/download/mac/tcltk/ for current information about supported and recommended versions of Tcl/Tk for this version of Python and of Mac OS X.  For this developer preview, the installer is still linked with Tcl/Tk 8.5.

Other changes

For other changes in this release, see the What's new section in the Documentation Set for this release and its Release Notes link at https://www.python.org/downloads/.

Python 3 and Python 2 Co-existence

Python.org Python $VERSION and 2.7.x versions can both be installed on your system and will not conflict. Command names for Python 3 contain a 3 in them, python3 (or python$VERSION), idle3 (or idle$VERSION), pip3 (or pip$VERSION), etc.  Python 2.7 command names contain a 2 or no digit: python2 (or python2.7 or python), idle2 (or idle2.7 or idle), etc.