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# Session and Top-Level Functionality

- Session
- Miscellaneous

## Session

Tecplot Engine and Tecplot 360 EX License management.

The `session` module contains methods used to manipulate the Tecplot Engine such as notification of a state-change that was done outside of PyTecplot. It also contains methods for acquiring and releasing the Tecplot 360 EX License.

`tecplot.session.``stop`()

  Releases the Tecplot 360 EX License and shuts down Tecplot Engine.

  This shuts down the Tecplot Engine and releases the Tecplot 360 EX License. Call this function when your script is finished using PyTecplot. Calling this function is not required. If you do not call this function, it will be called automatically when your script exists. However, the Tecplot 360 EX License will not be released until you call this function.

  Note that stop() may only be called once during the life of a Python session. If it has already been called, subsequent calls do nothing.

  See also: `tecplot.session.acquire_license()`, `tecplot.session.release_license()`.

  Example:

      >>> import tecplot
      >>> # Do useful things with pytecplot
      >>> tecplot.session.stop() # Shutdown tecplot and release license

`tecplot.session.``acquire_license`()

  Attempts to acquire the Tecplot 360 EX License

  Call this function to attempt to acquire a Tecplot 360 EX License. If Tecplot Engine is not started, this function will start the Tecplot Engine before attempting to acquire a license.

  This function can be used to re-acquire a license that was released with `tecplot.session.release_license`.

  If the Tecplot Engine is currently running, and a Tecplot 360 EX License has already been acquired, this function has no effect.

  Licenses may be acquired and released any number of times during the same Python session.

  Raises `TecplotLicenseError` if a valid license could not be acquired.

  Note

  Warning emitted when close to expiration date.

  A warning is emitted using Python’s built-in `warnings` module if you are within 30 days of your TecPLUS subscription expiration date. The message will look like this:

      $ python
      Python 3.4.5 (default, Jun 27 2016, 13:24:59)
      [GCC 4.8.5 20150623 (Red Hat 4.8.5-4)] on linux
      Type "help", "copyright", "credits" or "license" for more information.
      >>> import tecplot
      >>> tecplot.session.acquire_license()
      /path/to/tecinterprocess.py:458: UserWarning:
      Your Tecplot software maintenance subscription
      (TecPLUS) will expire in **13 days**, after which you
      will no longer be able to use PyTecplot. Contact
      sales@tecplot.com to renew your TecPLUS subscription.

        warn(warning_msg)
      >>>

  These warnings can be suppressed by using the `-W ignore` option when invoking the python interpreter:

      $ python -W ignore
      >>> import tecplot
      >>> tecplot.session.acquire_license()
      >>>

  See also: `tecplot.session.release_license()`

  Example:

      >>> import tecplot
      >>> # Do useful things
      >>> tecplot.session.release_license()
      >>> # Do time-consuming things not related to |PyTecplot|
      >>> tecplot.session.acquire_license()  # re-acquire the license
      >>> # Do useful |PyTecplot| related things.

`tecplot.session.``release_license`()

  Attempts to release the Tecplot 360 EX License

  Call this to release a Tecplot 360 EX License. Normally you do not need to call this function since `tecplot.session.stop()` will call it for you when your script exists and the Python interpreter is unloaded.

  This function can be used to release a license so that the license is available to other instances of Tecplot 360 EX.

  If the Tecplot 360 EX License has already been released, this function has no effect.

  Licenses may be acquired and released any number of times during the same Python session.

  See also: `tecplot.session.acquire_license()`

  Example usage:

      >>> import tecplot
      >>> # Do useful things
      >>> tecplot.session.release_license()
      >>> # Do time-consuming things not related to |PyTecplot|
      >>> tecplot.session.acquire_license()  # re-acquire the license
      >>> # Do useful |PyTecplot| related things.

`tecplot.session.``start_roaming`(days)

  Check out a roaming license.

  Parameters: | days (`integer`) – Number of days to roam.

  This will acquire a PyTecplot license and then attempt to set it up for roaming. The maximum number of days one may roam is typically 90. This function can be called in an interactive terminal and will affect all subsequent uses of PyTecplot on the local machine. Do not forget to `release` the roaming license to the server if you are finished roaming before the expiration date.

  See also: `tecplot.session.stop_roaming()`

  Example usage:

      >>> tecplot.session.start_roaming(10)
      You have successfully checked out a roaming license of
      PyTecplot. This will be valid for 10 days until
      midnight of 2017-01-15.
      >>> tecplot.session.stop_roaming()
      Your PyTecplot roaming license has been checked in.

`tecplot.session.``stop_roaming`(force=False)

  Check in (release) a roaming license.

  This will check in and make available to others on the network a license that you previously checked out for roaming.

  See also: `tecplot.session.start_roaming()`

  Example usage:

      >>> tecplot.session.stop_roaming()
      Your PyTecplot roaming license has been checked in.

`tecplot.session.``license_expiration`()

  Expiration date of the current license.

  Returns: `datetime.date`

  Example usage:

      >>> print(tecplot.session.license_expiration())
      2017-12-31

`tecplot.session.``tecplot_install_directory`()

  Tecplot 360 EX installation directory.

  Top-level installation directory for Tecplot 360 EX. This will typically contain configuration files and the examples directory.

  This directory is platform-dependent and will contain configuration files and the examples directory:

      import os
      import tecplot

      installdir = tecplot.session.tecplot_install_directory()
      infile = os.path.join(installdir,'examples','3D','spaceship.lpk')
      outfile = 'spaceship.png'
      tecplot.load_layout(infile)
      tecplot.export.save_png(outfile, 600)

`tecplot.session.``tecplot_examples_directory`()

  Tecplot 360 EX examples directory.

  Examples directory that is typically installed with Tecplot 360 EX. This may be overridden with the TECPLOT_EXAMPLES environment variable.

  This directory is platform-dependent and by default contains the various examples shipped with Tecplot 360 EX:

      import os
      import tecplot

      exdir = tecplot.session.tecplot_examples_directory()
      infile = os.path.join(exdir,'3D','JetSurface.lay')
      outfile = 'jet_surface.png'
      tecplot.load_layout(infile)
      tecplot.export.save_png(outfile, 300)

## Miscellaneous

class `tecplot.tecutil.``Index`

  Position identifier type.

  This type is used internally to represent a position in a list. It is used to indicate that a change between zero-based indexing and one-based indexing must occur at the TecUtil boundary.

  This type can be treated exactly like a Python native `int` and is only meaningful internally to the tecplot Python module.

class `tecplot.tecutil.``IndexRange`(min, max, step)

  Index range specification along some axis.

  This is similar to Python’s `slice` object except that `max` is included in the evaluated indexes. Here are some things to note:

  > - All indices start with 0 and go to some maximum index `m`.
  > - Negative values represent the indexes starting with the maximum at -1 and continuing back to the beginning of the range.
  > - A step of `None`, 0 and 1 are all equivalent and mean that no elements are skipped.
  > - A negative step indicates a skip less than the maximum.

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