PlugIn

class PlugIn.PlugIn(application, name, module)

Bases: object

Template for Webware Plug-ins.

A plug-in is a software component that is loaded by Webware in order to provide additional Webware functionality without necessarily having to modify Webware’s source. The most infamous plug-in is PSP (Python Server Pages) which ships with Webware.

Plug-ins often provide additional servlet factories, servlet subclasses, examples and documentation. Ultimately, it is the plug-in author’s choice as to what to provide and in what manner.

Instances of this class represent plug-ins which are ultimately Python packages.

A plug-in must also be a Webware component which means that it will have a Properties.py file advertising its name, version, requirements, etc. You can ask a plug-in for its properties().

The plug-in/package must have an __init__.py which must contain the following function:

def installInWebware(application):
    ...

This function is invoked to take whatever actions are needed to plug the new component into Webware. See PSP for an example.

If you ask an Application for its plugIns(), you will get a list of instances of this class.

The path of the plug-in is added to sys.path, if it’s not already there. This is convenient, but we may need a more sophisticated solution in the future to avoid name collisions between plug-ins.

Note that this class is hardly ever subclassed. The software in the plug-in package is what provides new functionality and there is currently no way to tell the Application to use custom subclasses of this class on a case-by-case basis (and so far there is currently no need).

Instructions for invoking:

# 'self' is typically Application. It gets passed to installInWebware()
p = PlugIn(self, 'Foo', '../Foo')
willNotLoadReason = plugIn.load()
if willNotLoadReason:
    print(f'Plug-in {path} cannot be loaded because:')
    print(willNotLoadReason)
    return None
p.install()
# Note that load() and install() could raise exceptions.
# You should expect this.

__init__(application, name, module)

Initializes the plug-in with basic information.

This lightweight constructor does not access the file system.

directory()

Return the directory in which the plug-in resides. Example: ‘..’

examplePages()

examplePagesContext()

hasExamplePages()

install()

Install plug-in by invoking its installInWebware() function.

load(verbose=True)

Loads the plug-in into memory, but does not yet install it.

Will return None on success, otherwise a message (string) that says why the plug-in could not be loaded.

module()

Return the Python module object of the plug-in.

name()

Return the name of the plug-in. Example: ‘Foo’

path()

Return the full path of the plug-in. Example: ‘../Foo’

properties()

Return the properties.

This is a dictionary-like object, of the plug-in which comes from its Properties.py file. See MiscUtils.PropertiesObject.py.

serverSidePath(path=None)

setUpExamplePages()

Add a context for the examples.

exception PlugIn.PlugInError

Bases: Exception

Plug-in error.

__init__(*args, **kwargs)

args

with_traceback()

Exception.with_traceback(tb) – set self.__traceback__ to tb and return self.