When programming in the two IDEs i used, bad things happen when i use raw_input. However on the command line it works EXACTLY how i expect it to. Typically this app is ran in cmd line but i like to edit and debug it in an IDE. Is there a way to detect if i executed the app in an IDE or not?
if sys.stdin.isatty():
# command line (not a pipe, no stdin redirection)
else:
# something else, could be IDE
I would strongly advise (and you have been previously advised on this) to use a good IDE, and a good debugger instead of hacking around your code to fix something that shouldn't be broken in the first place.
I deserve to be down-voted for not answering the question, but please consider this advice for your future sanity.
I would personally recommend Winpdb debugger and PIDA IDE
Related
so far I used the Komodo IDE for Python development, but I'm now testing Eclipse with PyDev. Everything works fine, but there is one Komodo feature that I'm missing.
In Komodo I can inspect the running application in a debugger shell. I.e. after hitting a breakpoint I can not only read the content of variables, but I can execute arbitrary Python code (e.g. changing the value of variables) and then continue program execution.
PyDev has also some interactive shell during debugging, but I can only read variables and not change their content. Is this feature not available in PyDev or am I missing something here?
Many thanks,
Axel
As you've seen, you can just use the console directly:
http://pydev.org/manual_adv_debug_console.html
Now, you can also connect the interactive console (which is a bit more advanced) by selecting a stack frame to attach it:
http://pydev.org/manual_adv_interactive_console.html
Yes you can do that. Just type in the console what ever commands you want :). I usually have to right click then
Debug As >> Python run
PyDev is a little bit quirky, but you get used to it.
So I'm trying to setup the terminal in conjunction with Notepad++ and I'm a little confused. I've managed to download Python 2.7 and load it up in Powershell but I don't really know where to go from there. Do I even need to use a terminal? I know it says you can't use IDLE but it would be a lot easier. If anyone can guide me through getting the right setup to go on with the book I'd appreciate it a lot.
If you managed to get python running in the powershell following the Exercice 0, and you read the "Warning For Beginners" section, you can proceed to Exercice 1.
Why do they recommend that setup? Notepad++ is on Windows a powerful text editor very similar to other text editors, so you will soon get familiar with it. You will need to save your scripts in files and type a special line in the powershell to run and test them. That way you will get accustomed to running programs with arguments and if you make a failure, you can edit your code, save it and run it again.
In IDLE, you are already in a Python environment, so you cannot give arguments to your program inside it (actually you can but it's complex). You can also get an editor, save your file and run the script but also here it's a harder and less obvious way than Notepad++. When you get comfortable with the environment in that book you may change to get something that suits better your way of doing.
There is a high level logic error deep within my Python script, and pdb doesn't help to debug it. Is there any other way to see what is being executed after I run my script?
NOTE: Using pdb is too slow and inconvenient - I wish I could grep over all cases when my function is executed, instead of inspecting manually each and every call, set/unset breakpoints. The state is lost when I exit pdb and its user interface is more confusing than helpful - requires docs at hand.
UPDATE: made it clear that pdb is not an option, so the most popular Python debugging tips can not be applied
I would recommend using pdb. You can use
import pdb
at the top of your script, and then add the line
pdb.set_trace()
somewhere in the code where you want to trace the problem. When the script gets to that line, you will have an interactive console where you can check variable values, run your own checks, and see what is going on. You can use n to execute the next line, or c to continue to the next occurrence of set_trace(). Full documentation is here: http://docs.python.org/2/library/pdb.html.
Let me know if you have any specific questions!
No, there's no magic formula.
My best suggestion is to get a good IDE with a debugger, like JetBrains' PyCharm, and step through your code to see where you went wrong.
Most of the time these situations happen because you make assumptions about behavior that aren't true. Get a debugger, step through, and check your assumptions.
I found a way to do this using excellent trace module that comes with Python.
An example how to troubleshoot module installation problem:
python -m trace -t setup.py install > execution.log
This will dump all source line of setup.py install execution to execution.log. I find this more useful than pdb, because usability of pdb command line interface is very poor.
I have a program that opens a lot of folders right now, and I am hoping that I can use the already open explorer instances to open new ones. I have this code:
import subprocess
subprocess.Popen(r'explorer /select,"C:\path\of\folder\file"')
I have seen threads on doing this in C#. Does anyone know a way it can be done in Python?
Thanks,
Ben
I do not believe you can do this. If there is any hope you will probably need to look at Python for .Net, you might give IronPython a try. But the code above using subprocess is simply giving you the same result as if you ran that string in command line. Which launches the explorer application with those arguments. But once its started, its off running on its own. Its not looking for command line input any more. I've looked at the list of command line arguments for explorer, and I see nothing that would indicate you can manipulate it once its running. Sorry, hope this helps.
How can you save functions/ classes you've writing in a python interactive session to a file? Specifically, is there a way in pydev / eclipse's interactive session (on a mac) to do this?
I just started learning python - and am enjoying using the interpreter's interactive session for testing and playing with modules I've written. However, I find myself writing functions in the interpreter, which I think, oh it would be cool to save that to my script files. How do I do this?
I tried:
import pickle
pickle.dump(my_function, open("output.p", "w"))
But it seems to be more of a binary serialization, or at least nothing that I could copy and paste into my code...
Are there ways to see the code behind classes & functions I've defined in the interpreter? And then copy them out of the interpreter?
Update:
Ok, here's what I've learned so far:
I missed the easiest of all - PyDev's interactive session in eclipse allows you to right click and save your session. Still have to remove >>>'s, but gets the job done.
IPython is apparently the way to go to do this.
How to save a Python interactive session? has more details.
The best environment for interactive coding sessions has to be IPython, in my opinion. It's built on and extends the basic Python interpreter with a lot of magic, including history. For example, you can issue the command %logstart to dump all subsequent input to a file, which still needs to be edited afterward before it will be a script, but gives you a lot to work with.
When installing IPython, don't forget pyreadline.
In general, however, it is best to write code in an IDE and then run it. IPython helps here as well. If you write and save the script, then use the IPython "run" command to run it, the entire global namespace of the script will be available for inspection in your IPython session. Additionally, you can use the -d argument to run to trigger the pdb debugger immediately on any unhandled exception.
If you're more of a straightlaced IDE and debugger kind of guy, then the easiest and best lightweight environment has to be PyScripter.
I think the answer is to change your workflow.
What I do is write my functions in an editor (emacs), and then press a key combination (Ctrl-c Ctrl-e) to send the region of text to the (i)python interpreter.
That way I can save the function if I want, and also play with it in an interpreter.
Emacs is central to how I do it, but I'm sure there must be similar approaches with many editors (vim, gedit, etc) and IDEs.
PS. Finding a good editor is crucial when working with Python. The editor must be able to move blocks of code to the left and right easily, or the whitespace issue becomes too onerous.
I dislike typing blocks of code in the python interpreter because it doesn't allow me to shift blocks easily. You'll like Python even more when you find the right editor.
You can setup a python history file which stores everything you type into the interpreter.
Here's how:
http://docs.python.org/tutorial/interactive.html
I think it can't be done.
Python can perform instrospection with the inspect module, but the inspect.getsource function won't work without a source file.