Develop Reference

VI auto completion Nonesense

I read that CTRL+P is the auto completion short cut in VI, but the recommendation given by the auto completion doesn't make that much sense to me.
Say from the re package there is a method called findall. Eclipse could recommend that method when I do CTRL+Space:
But When I tried the auto completion in VI, it could not find the findall method. the only recommendation seems like a command that I have typed before which has nothing to do with the re module.
Can Anyone give me some hints what is the auto completion story behind the CTRL+P in VI and how could I tune it up so it would be as good as Eclipse's auto completion.
(Every time I doubt the power of VI, the truth is always that it is me who lack the power to discover the beauty of VI)
Thanks!

In vim <C-p> is not the only completion shortcut available. Omni completion defined for python should be called with <C-x><C-o>, then use <C-n>/<C-p> to select variants. There are more completion types, all start with <C-x>, see :h ins-completion.
It is still better to use some third-party plugin (like jedi-vim or klen/python-mode) to get python completion as they are smarter. Note that at least klen/python-mode will not redefine <C-p>. They redefine <C-x><C-o> by setting 'omnifunc' option.

Without any additional modules, vim's autocompletion only searches the current file for occurences of the string you've started typing, regardless of whether it makes sense. If you use the tags file, via ctags or other, you're able to use strings across a variety of files, rather than just the current buffer.

Are there any keyboard shortcuts for formatting in Python?

After we write a code in Matlab we can use ctrl+A+ctrl+I and ctrl+A+ctrl+J to format our code (comments, loops alignment etc). Is there something similar or any helpful keyboard shortcuts in Python?
Also, just like we can use upward arrow to copy our previous command window history in Matlab, is it possible or some keyboard shortcut to do that in Python?
Thanks!

Python is a programming language, not an integrated development environment (IDE), therefore it has no "keyboard shortcuts" or the like. Each given development environment may offer different facilities or the like. You appear to consider GNU Readline (typically used in the simple text-mode interpreter environment that many Python executables bundle) as "part of Python" -- but that's a misconception; readline is a perfectly general library for interactive input in command-line environments, and Python only one of the many programs using it. Another environment usually bundled with Python is IDLE, a GUI one, and of course the editing facilities are completely and drastically different. There are many third-party environments such as "Wing IDE" and each offers a drastically different set of editing features and facilities from all the others.
To summarize: your question makes no more sense about Python per se than it would about (say) C, or Java, or any other programming languages. Don't let (usually proprietary) programming languages that come with bundled IDEs confuse you on this subject!

If you use the Python IDLE (comes with Python on Windows, readily available on Linux and Unix flavors), most of the formatting work is done for you. For instance, IDLE automatically indents loops and any other code block after a :. This is far better than writing Python scripts in a standard text editor like gedit, emacs, vim, or Notepad, especially since you can simply press F5 to run the script.
As for previous commands, the biggest disadvantage to the Python shell is that you cannot press the up arrow to get the last command. However, if you use the non-GUI shell (in the Windows command prompt or a Unix terminal, the command is python), you can use the shell's command recall to get the last command.

If you use emacs, then
you can press tab anywhere on a line and it will properly indent that line relative to the preceding line (making the assumption that the current block is continuing).
you can mark selections of text and press C-c < and C-c > to move blocks of text left and right.
These are the two that I actually use with any regularity. I'm sure that anything that any other editor can do, emacs can do too ;)
on the whole, formatting python code is difficult for a program to do because the indentation drastically affects semantics.
consider
for i, item in enumerate(lst):
if i % 2:
sum += i * int(item)
return sum
and
for i, item in enumerate(lst):
if i % 2:
sum += i * int(item)
return sum
Do you really want your editor deciding which one you mean?

Can I get Python debugger pdb to output with Color?

I'm using PDB a lot and it seems it would be even better if I could add systax highlighting in color.
Ideally, I'd like to have to the path to the code a lighter color.
The line of actual code would be syntax highlighted.
I'm using OS X and the Terminal app.
Python 2.7

pdb doesn't support colorization. However, it's not that hard to get it, even if you're a command-line addict (as I am;-) -- you don't have to switch to GUIs/IDEs just to get colorization while debugging Python. In particular, command-line tools usually work much better when you're accessing a remote machine via SSH, saving a lot of the bandwidth and latency issues that any remote access to GUIs and IDEs can inflict on you;-).
Specifically, for the task you're asking about, consider ipdb (you also need ipython, which offers a far more advanced shell than plain interactive Python, on which ipdb relies). Both offer you good tab completion, enhanced tracebacks, and colorization -- ipython for your normal interactive work, ipdb with the same features when you're debugging (otherwise just about the same as pdb).

You could try pudb, which works in the terminal and looks like this:
I haven't tried some of the options mentioned in other answers, but to judge from the PyPI pages, pudb is better maintained and better documented.

Take a look at pdb++ - it is a drop-in replacement for pdb that fills all your requirements and adds some other nice features such as tab completion and new commands such as watch and sticky.
Here is a sample config file that will enable colours (add this after creating the file: touch ~/.pdbrc.py):
import pdb
class Config(pdb.DefaultConfig):
use_pygments = True
pygments_formatter_class = "pygments.formatters.TerminalTrueColorFormatter"
pygments_formatter_kwargs = {"style": "monokai"}

This might not possible for you, but have you tried using a graphical debugger (like the one in eclipse/pydev)? It will give you your syntax highlighting and much more.
I only use pdb directly if I don't have an option, because a graphical interface is just that much nicer.

In case someone hit the problem with colorization in a console.
My console had white background while ipdb was also adding rather light colors to syntax (for example variables were white). Pressing man ipython shows that we have 3 colors available: 'nocolor', 'linux', 'LightBG'. Ipdb was in my case installed via easy_install into my virtualenv. So it was trivial to look into ipdb source and modify it (hint search for ipdb/init.py in your env). Then I've modified following:
def set_trace():
ip = ipapi.get()
+ def_colors = ip.options.colors
+ def_colors = 'LightBG'
Pdb(def_colors).set_trace(sys._getframe().f_back)
It's a kinda hackish solution but well its for debugging purpose on my working station so its sufficient. But if anyone finds something better. Please send me a message on what to do.

Quickhelp for Python in Emacs autocomplete.el?

I am using Emacs 23.1.1 on GNU/Linux with autocomplete.el 1.3 and Ropemacs 0.6.
In Lisp programming, autocomplete.el shows the documentation (known as 'QuickHelp' in autocomplete.el) of the suggested completions. Python completion with ropemacs works, but does not show quick help for the Python completion. Is it possible to enable it and did somebody make it work?

Ropemacs does the job : Use the function rope-show-doc over the symbol or use the keybinding C-c d. Simple :)

I stopped using all the autocomplete stuff in all my developing environments. They rarely do what I want. Either the lists is too long, or too short, or not sorted well. Therefore I use dabbrev-expand in all my modes global-set-key to tab.
This works even quote well for text. Usually it is enough to get a good expansion from the local buffer where you are in. If I start typing in an empty buffer I open a second one which expand can use to look up its suggestions. This is not language sensitive, not does depend on the object you want to call a method of, but its still a big boost, and you get used to it. Maybe its not, you don't get "quick help" this way.

Bash alias to Python script -- is it possible?

The particular alias I'm looking to "class up" into a Python script happens to be one that makes use of the cUrl -o (output to file) option. I suppose I could as easily turn it into a BASH function, but someone advised me that I could avoid the quirks and pitfalls of the different versions and "flavors" of BASH by taking my ideas and making them Python scripts.
Coincident with this idea is another notion I had to make a feature of legacy Mac OS (officially known as "OS 9" or "Classic") pertaining to downloads platform-independent: writing the URL to some part of the file visible from one's file navigator {Konqueror, Dolphin, Nautilus, Finder or Explorer}. I know that only a scant few file types support this kind of thing using some other command-line tools (exiv2, wrjpgcom, etc). Which is perfectly fine with me as I only use this alias to download single-page image files such as JPEGs anyways.
I reckon I might as well take full advantage of the power of Python by having the script pass the string which is the source URL of the download (entered by the user and used first by cUrl) to something like exiv2 which could write it to the Comment block, EXIF User Comment block, and (taking as a first and worst example) Windows XP's File Description field. Starting small is sometimes a good way to start.
Hope someone has advice or suggestions.
BZT

The relevant section from the Bash manual states:
Aliases allow a string to be
substituted for a word when it is used
as the first word of a simple command.
So, there should be nothing preventing you from doing e.g.
$ alias geturl="python /some/cool/script.py"
Then you could use it like any other shell command:
$ geturl http://example.com/excitingstuff.jpg
And this would simply call your Python program.

I thought Pycurl might be the answer. Ahh Daniel Sternberg and his innocent presumptions that everybody knows what he does. I asked on the list whether or not pycurl had a "curl -o" analogue, and then asked 'If so: How would one go about coding it/them in a Python script?' His reply was the following:
"curl.setopt(pycurl.WRITEDATA, fp)
possibly combined with:
curl.setopt(pycurl.WRITEFUNCITON, callback) "
...along with Sourceforge links to two revisions of retriever.py. I can barely recall where easy_install put the one I've got; how am I supposed to compare them?
It's pretty apparent this gentleman never had a helpdesk or phone tech support job in the Western Hemisphere, where you have to assume the 'customer' just learned how to use their comb yesterday and be prepared to walk them through everything and anything. One-liners (or three-liners with abstruse links as chasers) don't do it for me.
BZT