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I've been using ST2 for quite some time now and given that python is now my primary language, I decided to try PyCharm. It's somewhat cluttered and my love for Sublime is keeping me away. However, PyCharm is somehow able to do the following things which Sublime can't:
Typing a period after an object and getting the CORRECT list of all its attributes (Sublime can do this, sort of, except it returns random attributes)
Refactoring of variables across entire projects/folders
Show docstrings for methods defined with them
It has more important functions which Sublime can't do quite yet. I have many packages already installed in Sublime which can almost do what PyCharm can except for those 3 things above.
So back to the question: How can PyCharm supply this functionality given that Python is not a strongly typed language?
If you're looking for better autocompletion, try SublimeCodeIntel, available via Package Control. It takes a little while to index your built-in modules and third-party packages, but once it's ready it's quite helpful. For example, with Pandas I can define a dataframe:
df = pd.DataFrame(some_input_data)
then type df. and all the associated classes and methods of a DataFrame object come up. To set this up, you'll need to add the following to your user preferences (Preferences -> Settings - User):
"auto_complete_triggers":
[
{
"characters": ".",
"selector": "source"
}
]
along with any other triggers you may have.
UPDATE
While SublimeCodeIntel is a decent package, it doesn't always work well - it sometimes has issues finding newly-installed modules, the database can get corrupted, there can sometimes be significant delays in autocompletion, it has trouble with virtualenvs, and sometimes it just doesn't work. If you're using Sublime Text 3, I highly recommend using Anaconda instead (no relation to the Anaconda Python distribution). Once you set it up (a very brief process, basically you just specify which Python interpreter you'd like to use), it just works. There's no database to initialize or get corrupted, it automatically discovers when you've added new packages, it's very unobtrusive running in the background... I can't say enough good things about it. It uses the JEDI autocompletion module, among other things, and is fast and accurate. It automatically determines what type variables are, and fills in the completions with the appropriate methods and classes that can be called on it. You can have it do parameter completion as well, but that got a little annoying for me, so I turned it off. One thing it can't do is method chaining, but nothing's perfect. It also includes modules for code complexity checking and linting, which is fine, but I don't need it, and only want to lint when I want to lint, so I turned that off as well. The other major difference between it and SublimeCodeIntel is that Anaconda is Python-specific, while SCI supports a number of different languages.
I'd highly recommend giving Anaconda a try. Aside from the method chaining, I've been very happy with it, and haven't gone back. One cool thing you can do is assign different values to the "python_interpreter" setting in your project files, so you can easily use virtualenvs, or (like I do) have one project open for Python 2 coding, and another for Python 3.
Related
If I do refactoring in a library pyCharm does handle all depending applications which are known to the current running pyCharm instance.
But code which is not known to the current pyCharm does not get updated.
Is there a way to store the refactoring information in version control, so that depending applications can be updated if they get the update to the new version of the library?
Use Case:
class Server:
pass
gets renamed to
class ServerConnection:
pass
If a team mate updates the code of my library, his usage of Server needs to be changed to ServerConnection.
It would be very nice if pyCharm (or an other tool) could help my team mate to update his code automatically.
As far as I can tell this is not possible neither with a vanilla PyCharm nor with a plugin nor with a 3rd party tool.
It is not mentioned in the official documentation
There is no such plugin in the JetBrains Plugin Repositories
If PyCharm writes refactoring information to it's internal logs, you could build this yourself (but would you really want to?)
I am also not aware of any python specific refactorig tool that does that. You can check for yourself: there is another SO question for the most popular refactoring tools
But ...
I am sure there are reasons why your situation is like it is - there always are good reasons (and most of the time the terms 'historic and 'grown' turn up in explanations of these reasons) but I still feel obligated to point out what qarma already mentioned in his comment: the fact that you want to do something like replaying a refactoring on a different code base points towards a problem that should be solved in a different way.
Alternative 1: introduce an API
If you have different pieces of software that depend on each other on such a deep level, it might be a good idea to define an API that decouples the code bases from each others internals. With an API it is clear which parts have to be stable. If changes have to be done on the API level they must be communicated and coordinated with the involved teams.
Alternative 2: Make it what it actually is: one code base
If A1 for whatever reason is not possible I would conclude that you actually have one system distributed over different code bases and then those should be merged into one code base. Different teams can still work on the same code base (hopefully using a DVCS) but global refactorings can be done with tooling help and they reach all parts of the system.
Alternative 3: Make these refactorings in PyCharm over all involved code bases
Even if you can't merge them into one code base you could combine them easily in PyCharm by loading different projects into the same Window. I do this without problems with two git projects that have to be in different repositories but still share certain aspects. PyCharm handles commits to these repositories transparently: if you make changes in several repositories and commit them you write one commit message and the commits will be done to all repositories.
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I have been programming using Python for slightly more than half an year now and I am more interested in Python internals rather than using Python to develop applications. Currently I am working on porting a few libraries from Python2 to Python3. However, I have a rather abstract view on how to make port stuff over from Python2 to Python3 as most of the changes deal with design issues in Python2.x
I'd like to learn more about Python internals; should I go for a top-down or a bottom-up approach? Are there any references you could recommend?
It sounds like you want to know more about the rationale behind the design of the language, rather than internals. "internals" to me means things like how objects are laid out in memory, how reference counting works, and so on.
If you're looking for a deeper understanding of the design decisions, try reading the PEPs: they are the proposals for changes in the language, and often include detailed discussions of the reasons for the changes, rejected alternatives, and so on. Even the rejected PEPs are useful, because they show the thinking that has shaped the language.
For example:
3105: Making print a function
3110: Catching exceptions in Python 3.x
3131: Supporting non-ASCII identifiers
and so on..
If you really want to learn about Python internals, then start by reading about the Python C API, which is used to build Python itself: my talk A Whirlwind Excursion through Python C Extensions is one place to start. Then you can dive into the Python source code itself for anything you need to learn about.
To someone who is stumbling upon this question from related links or search, there is a documentation written Yaniv Aknin on Python Internals. It starts from the scratch and is highly readable.
I find the series of Yaniv Aknin's Pythons Innards series
fantastic, too
I discovered it thanks to Planet Python
.
You may be also interested by the answer of TryPyPy in this SO thread
I would first read the What's New document for Python 3. It gives a good high-level overview and touches on the detailed changes.
You might also do a search for 'porting to python 3' or similar. There are lots of good resources and tools.
One tool that's new and hard to find is six, by Benjamin Peterson. It enables writing of code that is compatible across the Python 2*3 gap.
The part I found most difficult about maintaining Python 2 and Python 3 -compatible code was deployment. I could write code that would run just fine, but when I went do package and deploy, it was unclear when the conversion should happen. I ultimately found a distutils command build_py_2_to_3 that would do the trick. By using that command in my setup.py, I could release a source distribution that would deploy on either Python 2 or Python 3. An example can be found in jaraco.util.
You also asked about the internals. If you really want to get at the internals, you can view the source for Python 2.x and Python 3.x, though honestly, I would stick with reading the tutorials and maybe some of the .py files in the Python libs.
should I go for a top-down or a bottom-up approach?
Both! Seriously.
Have you tried this?
Automated Python 2 to 3 code
translation
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I'm working on a Python web application in which I have some small modules that serve very specific functions: session.py, logger.py, database.py, etc. And by "small" I really do mean small; each of these files currently includes around 3-5 lines of code, or maybe up to 10 at most. I might have a few imports and a class definition or two in each. I'm wondering, is there any reason I should or shouldn't merge these into one module, something like misc.py?
My thoughts are that having separate modules helps with code clarity, and later on, if by some chance these modules grow to more than 10 lines, I won't feel so bad about having them separated. But on the other hand, it just seems like such a waste to have a bunch of files with only a few lines in each! And is there any significant difference in resource usage between the multi-file vs. single-file approach? (Of course I'm nowhere near the point where I should be worrying about resource usage, but I couldn't resist asking...)
I checked around to see whether this had been asked before and didn't see anything specific to Python, but if it's in fact a duplicate, I'd appreciate being pointed in the right direction.
My thoughts are that having separate
modules helps with code clarity, and
later on, if by some chance these
modules grow to more than 10 lines, I
won't feel so bad about having them
separated.
This. Keep it the way you have it.
As a user of modules, I greatly prefer when I can include the entire module via a single import. Don't make a user of your package do multiple imports unless there's some reason to allow for importing different alternates.
BTW, there's no reason a single modules can't consist of multiple source files. The simplest case is to use an __init__.py file to simply load all the other code into the module's namespace.
Personally I find it easier to keep things like this in a single file, just for the practicality of editing a smaller number of files in my editor.
The important thing to do is treat the different pieces of code as though they were in separate files, so you ensure that you can trivially separate them later, for the reasons you cite. So for instance, don't introduce dependencies between the different pieces that will make it hard to disentangle them later.
For command line scripts there most likely will not be much difference unless each invocation invokes all files in the module, in which case there will be a slight performance cost as n files need to be opened vs one.
For mod_python there most likely will be no difference as byte-compiled modules stay alive for the duration of the apache process.
For google app engine though there will be a performance hit unless the service is constantly used and is "hot" as each cold start would require opening all files.
Off course you can have as many modules as you like.
But now let as think a little, what happens when we put every small code snippet into one single file.
We will end up in hundreds of import statements in any less trivial module. And off course you could also save a little by having all explicit in seperated files. But guess what: Nobody can remember so many module names and you might end up in searching for the right file anyway ...
I try to put things that belong together in one single file (unless it becomes to big!). But when I have small functions or classes that do not belong to other components in my system, I have "util" modules or the like. I also try to group these for example according to my application layering or seperate them by other means. One seperation criteria could be: Utilities that are used for UI and those that are not.
Small.
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I'm downloading Python 3.1.1 and that comes with the IDLE correct?
I'm also downloading QT for Windows which I'm told is a good GUI framework to work with Python.
What projects should I try to make in order to grasp some of the goodies Python brings to the table?
Thanks a bunch SO.
I highly recommend
http://www.diveintopython3.net
It assumes you already understand programming, and walks you through examples that demonstrate the unique abilities of Python.
Do the next project you intended to program with your prefered language with Python.
If you are new to python, why not start with some simpler command line projects? I know you said you are not new to development, but maybe you should spend some time with the core python stuff before tacking on a GUI framework. Just a suggestion.
Also, I would point out that Python 3+ code looks a bit different than a lot of the python 2.x code samples you will see around the internet. I have found Python 3 to be not the best in terms of backward compatibility. You might want to start out with a 2.x version of Python to get the most out of the plethora of Python tutorials on the internet, then move to Python 3 if you need it.
Write a simple Text Editor.
That was one of the projects i started when i first learned python. It gets you used to the GUI framework, file IO, many types, OOP, lots... It's something that you can grow over time as your confidence builds and it's cross platform so it's handy.
If python is your first dynamic lanugage you might want to play with some of it's dynamic aspects.
For example, using the getattr and setattr methods on objects, you could write a class that provides a fluent way of accessing elements from an XML document. Rather calling methods on an object with parameters like 'xml.getnode("a").getnode("b")' you could dynamically lookup the nodes as attributes and allow 'xml.a.b' instead. I thought this was very cool having come from static languages.
Note that this won't neccessarily give you a great feel for python in general (although you'll pick up the language as you go) but it will give you a taste of what is possible in dynamic languages.
PythonChallenge
Code Golf
Google Code Jam
These are good ways to practice learning Python.
Might I also suggest that you consider using a different IDE.
If you are interested in GUI programming, I would suggest looking into wxPython, PyWin32, easyGUI, TkInter (which is bundled with the Python distribution)
Python Challenge This is fun and interesting to learn Python programming.
While it is a matter of personal preference, I certainly wouldn't want to play around with a GUI framework when starting out -- I would want to get a feel for the language first by playing around with smaller snippets, such as those suggested on Code Golf. While getting your code to fit into the smallest number of bytes perhaps isn't the best way to learn good design, I think it's a good way to learn parts of the language. Certainly, just doing the tasks without necessarily trying to compact them down excessively could be helpful.
A project I wish someone would write: a friendly GUI that wraps around the scanner library and the PDF library, and lets the user easily scan and file documents.
It would have a toolbar with big buttons: "scan letter", "scan brochure", "scan photo". These would respectively choose high-resolution black-and-white, medium-resolution color, and high-resolution color.
The user would plop down the document and hit one of those buttons. Python would wake up the scanner and have it scan, and then would use Python Image Library or something to auto-detect the size of the actual scanned document and auto-crop down to minimal size.
For "scan photo" you would get a JPEG. For the others, you would get a PDF. And it would have an option where you could scan several pages and then select the scanned pages, and say "group" and it would make a single PDF out of them.
Other useful toolbar buttons would be: "Copy Letter", "Copy Brochure", "Copy Photo". These would scan and then immediately print on an appropriate output device (or just on the default output device for your first version).
If you want to go crazy, you could add an OCR function to try to recover searchable text from the scanned images, and put that in the PDF as tags or something.
Someday I will write this if nobody else does...
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I have a bunch of classes I want to rename. Some of them have names that are small and that name is reused in other class names, where I don't want that name changed. Most of this lives in Python code, but we also have some XML code that references class names.
Simple search and replace only gets me so far. In my case, I want to rename AdminAction to AdminActionPlug and AdminActionLogger to AdminActionLoggerPlug, so the first one's search-and-replace would also hit the second, wrongly.
Does anyone have experience with Python refactoring tools ? Bonus points if they can fix class names in the XML documents too.
In the meantime, I've tried it two tools that have some sort of integration with vim.
The first is Rope, a python refactoring library that comes with a Vim (and emacs) plug-in. I tried it for a few renames, and that definitely worked as expected. It allowed me to preview the refactoring as a diff, which is nice. It is a bit text-driven, but that's alright for me, just takes longer to learn.
The second is Bicycle Repair Man which I guess wins points on name. Also plugs into vim and emacs. Haven't played much with it yet, but I remember trying it a long time ago.
Haven't played with both enough yet, or tried more types of refactoring, but I will do some more hacking with them.
I would strongly recommend PyCharm - not just for refactorings. Since the first PyCharm answer was posted here a few years ago the refactoring support in PyCharm has improved significantly.
Python Refactorings available in PyCharm (last checked 2016/07/27 in PyCharm 2016.2)
Change Signature
Convert to Python Package/Module
Copy
Extract Refactorings
Inline
Invert Boolean
Make Top-Level Function
Move Refactorings
Push Members down
Pull Members up
Rename Refactorings
Safe Delete
XML refactorings (I checked in context menu in an XML file):
Rename
Move
Copy
Extract Subquery as CTE
Inline
Javascript refactorings:
Extract Parameter in JavaScript
Change Signature in JavaScript
Extract Variable in JavaScript
WingIDE 4.0 (WingIDE is my python IDE of choice) will support a few refactorings, but I just tried out the latest beta, beta6, and... there's still work to be done. Retract Method works nicely, but Rename Symbol does not.
Update: The 4.0 release has fixed all of the refactoring tools. They work great now.
I would take a look at Bowler (https://pybowler.io).
It's better suited for use directly from the command-line than rope and encourages scripting (one-off scripts).
Your IDE can support refactorings !!
Check it Eric, Eclipse, WingIDE have build in tools for refactorings (Rename including). And that are very safe refactorings - if something can go wrong IDE wont do ref.
Also consider adding few unit test to ensure your code did not suffer during refactorings.
PyCharm have some refactoring features.
PYTHON REFACTORING
Rename refactoring allows to perform global code changes safely and instantly. Local changes within a file are performed in-place. Refactorings work in plain Python and Django projects.
Use Introduce Variable/Field/Constant and Inline Local for improving the code structure within a method, Extract Method to break up longer methods, Extract Superclass, Push Up, Pull Down and Move to move the methods and classes.
You can use sed to perform this. The trick is to recall that regular expressions can recognize word boundaries. This works on all platforms provided you get the tools, which on Windows is Cygwin, Mac OS may require installing the dev tools, I'm not sure, and Linux has this out of the box. So grep, xargs, and sed should do the trick, after 12 hours of reading man pages and trial and error ;)