grim/pyscovery
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2013-04-09, Gary Kramlich
846cc40f38e9
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# pyscovery - A python plugin finder
# Copyright (C) 2013 Gary Kramlich <grim@reaperworld.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
pyscovery is a Python plugin loader that will search for classes based from a
list of modules and optionally use the file system to recurse into packages.
This is different from pkg_resources and friends since it doesn't require you
to add every module that might have packages, it will discover it for you.
I wrote this because none of the existing solutions fit my need of being able
to logically group similar plugins in the filesystem.
Say you have the following structure in your project:
module/
__init__.py
plugin.py
plugins/
__init__.py
plugin1/
__init__.py
plugin2/
__init__.py
plugin3.py
With pyscovery, the following code will find plugins 1, 2, and 3 for you:
import pyscovery
from plugin import Plugin
pyscovery.add_module('plugins')
for plugin in pyscovery.find(Plugin, recurse=True):
print plugin
Recursion in the filesystem is off by default, since that's the way people are
used to. If there is enough demand, I will make it the default.
"""
import
fnmatch
import
importlib
import
inspect
import
os
# we use a list since it is a mutable sequence type. Meaning we can add to it
# while iterating.
MODULES
=
[]
__version__
=
'1.0'
def
add_module
(
module
):
"""
Adds a module to search for plugins under
"""
global
MODULES
# pylint:disable-msg=W0602
if
not
module
in
MODULES
:
MODULES
.
append
(
module
)
def
remove_module
(
module
):
"""
Removes a module to search for plugins under
"""
global
MODULES
# pylint:disable-msg=W0602
if
module
in
MODULES
:
MODULES
.
remove
(
module
)
def
get_modules
():
"""
Returns the list of all module to search under
"""
return
MODULES
def
clear_modules
():
"""
Clears all search modules
"""
MODULES
[:]
=
[]
def
find
(
cls
,
recurse
=
False
):
"""
Find all plugins that are subclasses of cls in the current search paths
"""
if
not
inspect
.
isclass
(
cls
):
raise
TypeError
(
'
{}
is not a class instance'
)
cls_name
=
cls
.
__name__
for
module
in
MODULES
:
mod
=
importlib
.
import_module
(
module
)
if
recurse
and
_is_package
(
mod
):
_recurse
(
mod
)
for
symbol_name
in
dir
(
mod
):
if
symbol_name
==
cls_name
:
continue
symbol
=
getattr
(
mod
,
symbol_name
,
None
)
if
not
inspect
.
isclass
(
symbol
):
continue
if
inspect
.
isabstract
(
symbol
):
continue
yield
symbol
def
_is_package
(
module
):
"""
Returns true if the module's name is __init__, false otherwise
"""
filename
=
os
.
path
.
basename
(
module
.
__file__
)
base
,
_
=
os
.
path
.
splitext
(
filename
)
return
base
==
'__init__'
def
_recurse
(
module
):
"""
Adds additional modules from a package
"""
dirname
=
os
.
path
.
dirname
(
module
.
__file__
)
make_module
=
lambda
name
:
'.'
.
join
((
module
.
__name__
,
name
))
for
name
in
os
.
listdir
(
dirname
):
base
,
_
=
os
.
path
.
splitext
(
name
)
if
base
==
'__init__'
:
continue
filename
=
os
.
path
.
join
(
dirname
,
name
)
if
os
.
path
.
isdir
(
filename
):
add_module
(
make_module
(
base
))
elif
os
.
path
.
isfile
(
filename
):
if
fnmatch
.
fnmatch
(
name
,
'*.py'
)
or
\
fnmatch
.
fnmatch
(
name
,
'*.py[co]'
):
add_module
(
make_module
(
base
))
__all__
=
[
add_module
,
remove_module
,
get_modules
,
clear_modules
,
find
]