Python Refactoring with Rope and Traad – The rope library is a powerful tool for refactoring Python code, but to be truly useful it needs to be available to development environments. Traad is a tool which makes it simpler to integrate rope into nearly any tool by exposing a simple HTTP API. In this session we’ll look at how traad and rope work together, and we’ll see how traad integrates with at least one popular editor.

1. PYTHON REFACTORING
WITH ROPE AND TRAAD
Austin Bingham
Sixty North AS
0

2. HELLO!

3. PYTHON IS
EVERYWHERE!

4. WHAT IS ROPE?

5. A PYTHON LIBRARY FOR DOING
PYTHON REFACTORINGS

6. ROPE HAS POWERFUL IDE-
ORIENTED FEATURES
Code completion
Finding definitions and occurrences
Organizing imports
Looking up docstrings

7. ELEMENTS OF ROPE

8. PROJECT
Represents the files and directories containing code that rope
will manipulate.
Projectis the root object in rope

9. CREATE A PROJECT
fromrope.base.projectimportProject
project=Project('project_dir')

10. RESOURCES
The files and directories in the project
server=project.get_resource('traad/server.py')
print(server.name,
server.path,
server.is_folder())
c1=project.get_resource('').get_children()[0]
print(c1.name,
c1.path,
c1.is_folder())

11. WALK PROJECT RESOURCES
defget_all_resources(proj):
todo=['']
whiletodo:
res_path=todo[0]
todo=todo[1:]
res=proj.get_resource(res_path)
yield(res.path,res.is_folder())
ifres.is_folder():
todo.extend((child.pathforchildinres.get_children()))
Project.get_resource(path)finds a resource at a
relative path
Resource.get_children()returns an iterable over
children

12. MANAGE PREFERENCES
prefsis a dict-like container of settings and preferences.
forpinproject.prefs.prefs:
print(project.prefs.get(p))
prefsare stored in a file called .ropeproject/config.py
at the project's root directory.

13. ANATOMY OF A
REFACTORING

14. CREATE THE REFACTORING
OBJECT
fromrope.refactor.renameimportRename
ren=Rename(project,
project.get_resource('traad/state.py'),
offset=42)
This can fail if rope can't perform the refactoring
The refactoring is only partially bound

15. CALCULATE ACTUAL CHANGES
changes=ren.get_changes('TacoCopter')
print(changes.description)
print(changes.get_changed_resources())
changesrepresents a fully bound change

16. EXECUTE THE CHANGES
project.do(changes)
After this the changes are actually performed.

17. THE FULL PROCESS
fromrope.base.projectimportProject
fromrope.refactor.renameimportRename
#Createtheproject
proj=Project('.')
#Createthepartially-boundrefactoring
ren=Rename(project,
project.get_resource('traad/state.py'),
offset=42)
#Calculatethechangesforafully-specifiedrenaming
change=ren.get_changes('TacoCopter')
#Performthechanges
project.do(changes())

18. HISTORY

19. HISTORYOBJECT
Project.historymanages the history of changes that have
been made.
Also remembers what has been undone as well as change
dependencies.

20. UNDOING CHANGES
Undo the most recent changes
project.history.undo()
Or select more distance changes to undo
change=project.history.undo_list[3]
project.history.undo(change)
This will undo all dependent changes.

21. REDOING CHANGES
You can redo changes that you've previously undone.
change=project.history.redo_list[-2]
project.history.redo(change)

22. MULTI-PROJECT
REFACTORING

23. THE MULTI-PROJECT
REFACTORING CLASS
First create a MultiProjectRefactoringinstance.
fromrope.refactorimportmultiproject
mpr=multiproject.MultiProjectRefactoring(
Rename,#typeofrefactoringtoperform
[other_project1,other_project2,other_project3])
Then call that with your main project and the refactoring
initializer arguments
ref=mpr(main_project,
some_resource,
offset=1337)

24. CREATE AND PERFORM THE CHANGE
#Rememberthat`ref`isarenamingoperation
changes=ref.get_all_changes(
"EnterpriseProxyManagerImplementationFactoryFactory")
multiproject.perform(changes)

25. NON-REFACTORING
TOOLS

26. NOT INTENDED FOR
"MANUAL" OPERATION

27. WHAT IS TRAAD?
tråd - svært tynn snor av fibrer av silke, ull, el. f eks av metall

28. WHAT IS TRAAD?
thread

29. TRAAD IS…
An HTTP+JSON server for driving rope

30. TRAAD IS…
Various clients for driving the server

31. WHY TRAAD?

32. SIMPLER INTEGRATION WITH
EDITORS
Every corner of the programming universe knows how to speak
HTTP+JSON

33. HTTP IS (WAY) MORE THAN FAST
ENOUGH FOR THIS WORK
The volume of data is low, and the response time only needs to
be good enough for humans

34. SUPPORT FOR MULTIPLE PYTHON
VERSIONS
The client has zero depenencies on the version of Python that
traad is using

35. PROPER LEVEL OF ABSTRACTION
The problem domain of traad is Python refactoring, not Python
integration with other languages.

36. TRAAD ARCHITECTURE

37. Low-ceremony (sorta), powerful, and well-documented

38. PYKKA FOR MANAGING
CONCURRENCY

39. OVERALL ARCHITECTURE

40. TASK STATE
{
1:{'status':'pending',
'description':'RenamingFOOtoBAR',
'changed_resources':[...]},
2:{'status':'failure'},
3:{'status':'success',
'calltip':'uuid1(node=None,clock_seq=None)'}
}
Simple mapping of task-ids to dicts
State is an actor and thus threadsafe. Multiple asynchronous
tasks could be accessing it at any time.

41. ASYNCHRONOUS OPERATIONS

42. SYNCHRONOUS OPERATIONS

43. ASYCHRONOUS VS.
SYNCHRONOUS
Asynchronous
Rename
Extract
Organize imports
Synchronous
Find definition
Get history
Calltip

44. EMACS
The emacs lisp for renaming looks like this
;Startsnewtraadserveronthespecifieddirectory
(traad-open"~/projects/roid_rage")
;Renameswhateverisathepoint(i.e.underthecursor)
(traad-rename"RagingRoid")
And the HTTP message looks like this
POST/refactor/renameHTTP/1.1
User-Agent:curl/7.30.0
Host:127.0.0.1:65172
Accept:*/*
Accept-Encoding:deflate,gzip
Content-Type:application/json
Content-Length:104
{"name":"RagingRoid",
"path":"/Users/sixtynorth/projects/roid_rage/roid_rage/roid.py",
"offset":102}

45. WHAT KIND OF A
KEYNOTE IS THIS?

46. ROPE AND TRAAD ONLY EXIST
BECAUSE OF CURIOUS
DEVELOPERS

47. IT CAN SEEM HOPELESS TO START
A PROJECT LIKE THIS

48. FIND THE NICHE THAT REALLY
INTERESTS YOU AND FILL IT

49. THERE IS NO FAME AND FORTUNE
IN THIS KIND OF DEVELOPMENT

50. BUT IT IS IMMENSELY SATISFYING
AND ENJOYABLE

51. YOU WILL LEARN A GREAT DEAL

52. AND YOU REALLY WILL BE
HELPING OTHERS

53. IT'S UP TO YOU, AND YOU CAN DO
IT!

54. SUPPORT ROPE AND TRAAD
The success of rope and traad depend on users and developers
like you!

55. LINKS
Rope -
Traad -
Pykka -
Bottle -
http://rope.sourceforge.net/
http://github.com/abingham/traad
http://www.pykka.org/
http://bottlepy.org/
http://github.com/abingham/traad_rope_presentation