Advanced Scripting

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While Wing's API will remain stable across future releases of the IDE, not all functionality is exposed by the API. Scripts can also be written to reach through Wing's API into internal functionality that may change from release to release, but in most cases stays the same. The most common reason to reach through the API is to add a new tool panel to Wing.

An example of this can be seen in pylintpanel.py in the scripts directory inside the the Install Directory listed in Wing's About box.

Working with Wing's Source Code

More advanced scripts like those that define a new tool are be easier to develop if Wing is run from its source code, usually as a debug process that is controlled by another copy of Wing.

To obtain Wing's source code, you must have a valid license to Wing Pro and must fill out and submit a non-disclosure agreement. Once this is done, you will be provided with access to the source code and further instructions.

How Script Reloading Works

Advanced scripters working outside of the API defined in wingapi.py should note that Wing only clears code objects registered through the API. For example, a script-added timeout (using CAPIApplication.InstallTimeout() method) will be removed and re-added automatically during reload, but a tool panel added using Wing internals will need to be removed and re-added before it updates to run on altered script code. In some cases, when object references from a script file are installed into Wing's internals, it will be necessary to restart Wing.

Script files that define _no_reload_scripts at the top level of the module will never be reloaded or unloaded. Files that define _ignore_scripts or that exist outside of the script path are also never reloaded.

Here is how reloading works:

  • All currently loaded script files are watched so that saving the file from an editor will cause Wing to initiate reload after it has been saved.
  • When a file changes, all scripts in its directory will be reloaded.
  • Wing removes all old scripts from the command registry, unregisters any timeouts set with CAPIApplication.InstallTimeout(), and removes any connections to preferences, attributes, and signals in the API.
  • Next imp.find_module is used to locate the module by name.
  • Then the module is removed from sys.modules and reloaded using imp.find_module and a module name that prepends internal_script_ to the module name, in order to avoid conflicting with other modules loaded by the IDE.
  • Wing executes the top level of the module as normal when importing a module in Python. This may cause signal connections and other calls to the API to occur.
  • If module load fails due to an error in the code, any timeouts or other connections registered by the module during partial load are removed and the module is removed from sys.modules.
  • If the module contains _ignore_scripts, then any timeouts or other connections are removed and scripts in the file are ignored.
  • Otherwise, Wing adds all the script-defined commands in the module to the command registry and loads any sub-modules in the same way, if the module is a package with __init__.py.

Note that reloading is by design slightly different than Python's builtin reload() function: Any old top-level symbols are blown away rather than being retained. This places some limits on what can be done with global data: For example, storing a database connection will require re-establishing the connection each time the script is reloaded.