When digging into legacy Python code and writing Python code myself, I often use pylint. I'm also using Clone Digger. I've recently started to use rope, which is a library for automated refactoring.
But I'm looking for something else than rope. I would prefer a tool that just makes suggestions about possible refactorings: names the refactoring, optionally provides a short description of it (great for learning purposes), highlights the code section and lets me do the refactoring myself. Is there such a tool?
Check out bicycle repair man http://bicyclerepair.sourceforge.net/
What is Bicycle Repair Man?
The Bicycle Repair Man project is an attempt to create refactoring browser functionality for python. It is packaged as a library that can be added to IDEs and editors to provide refactoring capabilities. Bindings for Emacs and Vi are included with the package.
Never used it myself, but have read about it. Sounds like what you are looking for.
You might like Pythoscope, an automatic Python unit test generator, which is supposed to help you bootstrap a unit test suite by dynamically executing code.
Also, have you checked out the rope.contrib.codeassist module? It is supposed to automatically propose and perform refactorings of your source code for you.
I don't if that type of tool exists in any specific language, although the concept was mentioned in Martin Fowler's refactoring book (web reference).
The best tool I know of that currently exists is cyclomatic complexity. This article implements a cyclomatic complexity counter for python.
The other easy metric to target is method/function length, number of attributes of objects/classes and number of parameters to functions, if I recall, pylint already counted those.
Oh Forget about your tool, instead use TDD and a good book like refactoring to design patterns by Kerievsky. The problem is that refactoring is a way to improve your code and design, but only You can know what you want to achieve, no refactoring tool can do it for you.
My point is that best way to learn refactoring is to study examples, not to follow some stupid/simple tools, because they wont teach you any sophisticated refactoring nor they will tell you if you have refactoring that compose well with you code.
PS Read Fowler "Refactoring" and Kerievsky "Refactoring to design Patterns" those books are must read when learning refactoring. And they mention simple way to checking if refactoring is needed (smells).
Also consider TDD as good way to ensure that your refs are safe and do not break your code.
Beck "Test-Driven Development by example" is a good book to start with.
And Python have PyUnit for TDD.
NetBeans has an early access version that supports Python, and it is rather nice. It has some basic refactoring tools that I found the be useful. As an added bonus it works on Windows, Linux, Mac OS X and Solaris.
Check it out at:
http://www.netbeans.org/features/python/
Related
I am going to write configuration tool for my Ubuntu based system. Next I would like to write frontends (text, GUI and web). But it is the most complicated project I wanted to write and I am not sure about general architecture I should use.
At the current I have functions and classes for changing system config. But these functions will probably grow & change. #Abki gave me advice how to write interface for frontends. I am going to make base classes for this interface but I don't know how to connect it with backend and next with frontends. Probably I should use design patterns like fasade, wrapper or something else.
It looks like (without interface_to_backend layer):
I don't care about UI and functions to change system config now. But I don't know how to write middle layer so It would be easy to connect it with the rest and extend functionality i the future.
I need general ideas, design patterns, advices how to implement this in Python.
I'm not sure this is entirely appropriate for SO but I'm intrigued and so I'll bite. As a rubyist I can't help much with the Python but here is some opinion on pattens from my experience.
My initial suggestion is you should review a few of the contenders out there. Specifically I'd be looking at cfengine, chef and bcfg2. They each tell a different story but if I'd summarise I'd say:
Chef has a lovely dsl syntax but is let down by a complicated architecture
bcfg2 is written in python but seems to have an annoying tendency to use XML :(
cfengine has the strongest theoretical underpinnings in promise theory (which is v.interesting BTW) but is C based.
Wikipedia also provides a pretty impressive list of configuration management tools that you will find useful.
In regard to designing your own tool I'd suggest there are three principles you want to pursue:
Simplicity, the simpler you make this the better. Simple in terms of scope, configuration and use are all important.
You'll need a single way to store data, you need to be able to trace the choices as they are made and not trample other people's changes (especially in a team environment).
Security, most configuration management tools need root privileges at some point. So you need to make sure that users can trust the code they're running.
You could use Fabric with Python as described in the article Ubuntu Server Setup with Python Fabric
The Wikipedia article at Comparison of open source configuration management software has several other tools that use Python to do this.
I like the approach taken by SALT.
If you write the GUI, text/CLI, and Web interfaces using Python, they can all use the same Python module. That way a change in one interface transparently affects the others. Plus all of those are in Python's area of strength.
there is a year old, similar question - but in case there have been changes afoot:
i'm an intermediate c++ programmer just starting out on python, post some online tuts etc i can do some basic pythoneering, but was wondering if there are good places i can look online for simple(ish) --pref console based-- code that i can learn from, ideally with some sort of commentary.
anything come to mind?
thanks
The standard library is an excellent place to the start. It's maintained by the core python team and is of high quality with a lot of interesting idioms. I'd recommend the newer modules since they don't have much backward compatibility cruft and are more representative of the language as it is now. The older ones were written for earlier versions of Python and have some restrictions when it comes to API changes etc.
The list of modules in the standard library is described at http://docs.python.org/library/. You can go through it and decide which one you want to look at (area of interest etc.).
Their sources are viewable at the mercurial repo here http://hg.python.org/cpython/file/d7e85ddb1336/Lib (as of today). These are for the mainline 2.6 release. You can also checkout the repo and browse it on your local machine.
You can also start up your interpreter, import a module (say os) and do a print os.__file__ to see where the source file is if you want to look at the code in your local editor.
ActiveState Recipes is a good source for all kinds of Python scripts. But if you want to learn the basics of Python, you might just want to look at the standard library that ships with Python ("lib" directory").
i came across This The other day, Probably you can learn some python basics and have a laugh too!
Anyways, look at the libs as they said above, they are very useful
If you enjoy riddles:
www.pythonchallenge.com
If you're an intermediate C++ programmer, you're already equipped to handle to programming concepts. I like it because it gives me a reason to learn each part of the language, without being mundane 'Hello World' tasks.
However, some of the riddles are pretty tough and/or unrelated to programming. Either way, doing the first few will probably be enough to get your confidence up with Python syntax.
I recall when I first read Pragmatic Programmer that they suggested using scripting languages to make you a more productive programmer.
I am in a quandary putting this into practice.
I want to know specific ways that using Python or Ruby can make me a more productive .NET developer.
One specific way per answer, and even better if you can say whether I could use Python or Ruby or Both for it.
See standard format below.
IronPython / IronRuby
IronPython in Action will do a better job explaining this (and exactly how best to use IronPython) that can possibly be accommodated in a SO answer. I'm biased -- I was a tech reviewer and am a friend of one of the authors -- but objectively think it's a great book. (No idea if IronRuby is blessed with a similarly wonderful book, yet).
As you want "one specific way per answer" (incompatible with SO, which STRONGLY discourages a poster posting 25 different answers if they have 25 "specific ways" to indicate...!-): prototyping in order to explore some specific assembly or collection thereof that you're unfamiliar with (to check if you've understood their docs right and how to perform certain tasks) is an order of magnitude more productive in IronPython than in C#, as you can explore interactively and compilation is instantaneous and as-needed. (Have not tried IronRuby but I'll assume it can work in a roughly equivalent way and speed).
Less Code
I think productivity is direct result on how proficient you are in a specific language. That said the terseness of a language like Python might save some time on getting certain things done.
If I compare how much less code I have to write for simple administration scripts (e.g. clean-up of old files) compared to .NET code there is certain amount of productivity gain. (Plus it is more fun which also helps getting the job done)
Advanced Text Processing
Traditional strengths of awk and perl. You can just glue together a bunch of regular expressions to create a simple data-mining system on the go.
Learning a new language gives you knowledge that you can bring back to any programming language. Here are some things you'd learn.
Add functionality to your objects on the fly.
Mix in modules.
Pass a chunk of code around.
Figure out how to do more with less code: ruby -e "puts 'hello world'"
C# can do some of these things, but a fresh perspective might bring you one step closer to automating your breakfast.
Embedding a script engine
Use of IronPython for a scripting engine inside your .NET application. For example enabling end-users of your application to change customizable parts with a full fledge language such as Python.
A possible example might be to expose custom logic to end-users for a work flow engine.
Quick Prototyping - Both
In the simplest cases when firing a python interpreter and writing a line or two is way faster than creating a new project in visual studio.
And you can use ruby to. Or lua, or evel perl, whatever. The point is implicit typing and light-weight feel.
Cross platform
Compared to .NET a simple script Python is more easily ported to other platforms such as Linux. Although possible to achieve the same with the likes of Mono it simpler to run a Python script file on different platforms.
Processing received Email
Python has built-in support for POP3 and IMAP where the standard .NET framework doesn't. Useful for automating email triggered tasks.
I'd like to parse Python source in order to try making a basic source code converter from Python to Go.
What module should I use?
Should I proceed or not?
If I should proceed, how?
Have a look at the language services packages, particularly the ast.
My guess is that if you don't already have a solid grasp of both parsing as well as code generation techniques, this is going to be a difficult project to undertake.
good luck!
As for the 'should I go ahead or better not' question: why do you want to do this in the first place?
If it's a purely learning exercise, then you don't don't need to ask us whether it's worthwhile. You want to learn, so go right ahead.
If it's meant to be a practical tool, then my suggestion is to not do it. An industrial-strength tool to perform such conversions might be useful but I would guess that you're not going to go that far. With that in mind it's probably more fruitful to rewrite the Python code in Go manually.
That assumes there is any real benefit to compiling to Go; current testing suggests that you get better performance and similar code structure from using Stackless Python.
The Boo Solution
Are you trying to make a python-like language, that can compiles into Go? This seems most sensible, as you will want to do Go-specific things (to take advantage of Go features).
Look at pyparsing. It includes an example of a complete python parser, but you probably don't want to do that.
You want to incrementally build your converter / translator, so you want to incrementally build the parser, otherwise you might choke on the AST. OK, you could parse everything and just ignore the stuff you don't understand, but that's not great behavior from a compiler.
You could start with parsing basic arithmetic.
The Pyrex Solution
This is similar to the Boo solution, but much harder. Get the Boo solution working first. Then learn to generate wrapper code, so your Go and python parts can work together.
The PyPy Solution
A complete Python-Go compiler? Good luck. You'll need it.
There's a good list of parsers rounded-up by Ned Batchelder which might help.
I want something simple in order to experiment/hack. I've created a lot interpreters/compilers for c and I just want something simple. A basic BASIC :D
If you don't know any (I've done my google search...), yacc/bison is the only way?
Thx
PLY is a great parser-creation library for Python. It has a simple BASIC interpreter as one of its example scripts. You could start there.
None of these listed in TheFreeCountry are acceptable? None of them are in Python, but I should think that starting from XBLite might be more helpful than starting from Yacc/Bison/PLY.
Also, Vb2py might be a better starting position than PLY.
If you must go the PLY route, however, consider the MOLE Basic grammar as a starting point rather than trying to roll your own from scratch.
I also don't know a basic interpreter under ruby, but given enough time and interest ruby easily "supports" writing an interpreter for any language you like: Agile DSL Development
in Ruby . I must admit that this approach comes with some investment of time. :(
At the end of the presentation are some links to further readings regarding DSLs.
You may wish to also examine the Parrot virtual machine which, according to wikipedia today, has some BASIC support.
a miniBasic in ruby is available here. Rockit seems WAY more fun that racc.
There is pybasic (python basic), rockit-minibasic (rubybasic).
To make these able to use the gui, then one has to develop extensions with kivy and shoes gui toolkits for pybasic and rockit-minibasic respectively and similarly prima gui for perlbasic if ever exists.