Input/Output Plugins

IO plugins are slightly different from the other plugin types. The __all__ variable must still be populated with the registration method, but it must provide a string identifier and a reference to an IOPlugin (available from the pluginbase module) subclass. The base class provides structure for what is required of an IO plugin:

class IOPlugin(Plugin):
   """
   All IOPlugins are expected to provide methods for opening and/or saving
   data files.
   """
   def __init__(self, filename=None, fcData=None, window=None):
      self.filename = filename
      self.fcData = fcData
      self.window = window

   def register(self):
          """
          Returns a dictionary keyed on the FILE_INPUT and
          FILE_OUTPUT IDs (found in data.io) to indicate which (if any) methods
          provide input and output functionality.
          """
          pass

   def fileType(self):
      """
      Returns a string used for identifying the file type(s) this plugin is
      capable of reading/saving.

      ex: 'Comma Separated Values (*.csv)|*.csv'
      """
      pass

   def read(self):
      """
      Given the specified path of a data file, input the data and return
      it along with the column labels, and any annotations or analysis.

      :@rtype: tuple
      :@return: (labels, data, annotations, analysis)
      """
      pass

   def save(self):
      """
      Write the FC data to the specified file.
      """
      pass

As is specified above, the IOPlugin subclass must provide a second registration to the FIND plugin system, indicating whether it can read files, write files, or both. This is done by having the register method return a dictionary as specified above with the keys for reading and writing methods coming from:

from data.io import FILE_INPUT, FILE_OUTPUT

Thus, having the register method return a dict with only the FILE_INPUT key and the reading method will cause FIND to only use the class for file input (available as an option in File..Open). If the FILE_OUTPUT method is also specified, FIND will place a menu item in File..Export with the string identifier given in the module register method. The final parameter to the class initializer is window. This provides a reference to the FIND window class so that plugins can show dialog boxes (or other window subclasses) with options for reading or writing. For an example of this, see the CSV plugin.