import pkg_resources

from PlugIn import PlugIn

class PlugInLoader:

def __init__(self, app):

self.app = app

def loadPlugIn(self, name, module, verbose=True):

"""Load and return the given plug-in.

May return None if loading was unsuccessful (in which case this method

prints a message saying so). Used by `loadPlugIns` (note the **s**).

"""

try:

plugIn = PlugIn(self.app, name, module)

willNotLoadReason = plugIn.load(verbose=verbose)

if willNotLoadReason:

print(f' Plug-in {name} cannot be loaded because:\n'

f' {willNotLoadReason}')

return None

plugIn.install()

except Exception:

print()

print(f'Plug-in {name} raised exception.')

raise

return plugIn

def loadPlugIns(self, plugInNames=None, verbose=None):

"""Load all plug-ins.

A plug-in allows you to extend the functionality of Webware without

necessarily having to modify its source. Plug-ins are loaded by

Application at startup time, just before listening for requests.

See the docs in `PlugIn` for more info.

"""

if plugInNames is None:

plugInNames = self.app.setting('PlugIns')

if verbose is None:

verbose = self.app.setting('PrintPlugIns')

if verbose:

print('Plug-ins list:', ', '.join(plugInNames))

entryPoints = {

entry_point.name: entry_point for entry_point

in pkg_resources.iter_entry_points('webware.plugins')}

plugIns = {}

for name in plugInNames:

if name in plugIns:

if verbose:

print(f'Plug-in {name} has already been loaded.')

continue

entry_point = entryPoints.get(name)

if not entry_point:

if verbose:

print(f'Plug-in {name} has no entry point.')

continue

module = entry_point.load()

plugIn = self.loadPlugIn(name, module, verbose=verbose)

if plugIn:

plugIns[name] = plugIn

if verbose:

print()

return plugIns