Being in the process of switching from Matlab to Python/IPython/Spyder I ran into the following issue.
In a Matlab script (and I actually did not notice this until I switched to Python) there is no warning if you are using a variable which you did not define in that script.
What I kept doing all the times in Matlab was to have, say, 2 (or more) scripts which I would then execute one after the other. The second script would typically use variables defined in the first, but would not give me any warning.
In Spyder I noticed that the situation is different. In my hypothetical second script, all the variables which are not defined in the second script itself give me a warning (undefined name '...'), which is not nice too see...
Another typical example, would be the following: I have a main script but there is something in this script I wanna look at better. So, without touching the script, I would create another file where I would copy paste a few lines from the script to play a little with them.
In this new file I would be using variables which are in the console already but that are techically unknown to the file itself, so would give me a warning.
So I guess I am simply asking if there a way to suppress this kind of warnings.
Or there might be a deeper question of whether there s a more pythonic way of working, but there I am really not sure about...
Related
I am trying to find a way that I can have a program step through Python code line by line and do something with the results of each line. In effect a debugger that could be controlled programmatically rather than manually. pdb would be exactly what I am looking for if it returned its output after each step as a string and I could then call pdb again to pickup where I left off. However, instead it outputs to stdout and I have to manually input "step" via the keyboard.
Things I have tried:
I am able to redirect pdb's stdout. I could redirect it to a second
Python program which would then process it. However, I cannot
figure out how to have the second Python program tell pdb to
step.
Related to the previous one, if I could get pdb to step all the way
through to the end (perhaps I could figure out something to spoof a
keyboard repeatedly entering "step"?) and redirect the output to a
file, I could then write another program that acted like it was
stepping through the program when it was actually just reading the
file line by line.
I could use exec to manually run lines of Python code. However,
since I would be looking at one line at a time, I would need to
manually detect and handle things like conditionals, loops, and
function calls which quickly gets very complicated.
I read some posts that say that pdb is implemented using
sys.settrace. If nothing else works I should be able to recreate
the behavior I need using this.
Is there any established/straight forward way to implement the behavior that I am looking for?
sys.settrace() is the fundamental building block for stepping through Python code. pdb is implemented entirely in Python, so you can just look at the module to see how it does things. It also has various public functions/methods for stepping under program control, read the library reference for your version of Python for details.
I read some posts that say that pdb is implemented using sys.settrace.
If nothing else works I should be able to recreate the behavior I need
using this.
Don't view this as a last resort. I think it's the best approach for what you want to accomplish.
I am trying to hot swap a file in python. I am creating a game that takes a really long time to load. But I don't want to reload it every time. I am trying to change some code while the programme is in runtime.
For example:
I want to change this:
while True:
print("Hello")
to this while in runtime:
while True:
print("Hello World")
I looked hot swapping up for python and all of them are answers that I am not looking for. All the other answers change modules. I want to change the current file. Like java in eclipse. Please help!
I want to change the current file. Like java in eclipse.
When you modify Java code in Eclipse, the code is not currently running. In reality, Eclipse has a Java compiler built-in, which attempts to compile your code as you type it. That's how Eclipse is able to give you such fast feedback about syntax errors and type errors in your code. But it can't give you any information about the runtime behaviour of your code (whether or not it produces the right answer), because it doesn't run the code! You need to press the Run button for that.
So I think the question you really want to ask is not "Can I dynamically modify Python code?" (the answer to that is "Yes, but it's complicated and has caveats and is not a good idea") but "Does there exist a Python IDE which can give me feedback about syntax errors while I type?" The answer to that is an emphatic "Yes!". There's an extremely comprehensive list of options in this answer.
You can use dynamic execution using exec function.
Store the code you want to execute in a string and change it during runtime.
I am working on a project whereby I need to embed Python within a Verilog file. The Python isn't really intended for execution in the normal sense as it will be read by a secondary tool. The Python will be written blocks that have some fixed demarcation (such as #+BEGIN_SRC, in org-babel).
module name ();
#+BEGIN_SRC python
def my_function ():
...
#+END_SRC
always #(posedge clk)
...
endmodule
Within Emacs this causes havoc, although Python-mode and Verilog-mode work fine, when combining both in the same file things quickly break-down as one would expect. Indentation is hopelessly broken as is syntax-highlighting. I understand this is a very weird thing to do, and I understand that there will almost certainly never been any real need to do this under normal circumstances, however for this particular case it is necessary.
My question: is there anyway within Emacs to specify multiple major modes within the same file. For example, is there some way that I can write a file using Verilog-mode as my major mode, but use Python-mode within the predefined blocks that are then ignored in the reset of the file.
There are a number of possibilities listed here:
http://emacswiki.org/emacs/MultipleModes
I've used multi-mode with latex and haskell, and it works OK.
I'm trying hard to like IPython Notebook, but maybe because I'm so used to writing code in vi and executing it at the command line I'm finding some of its defaults challenging. Can anything be done (perhaps in a configuration file somewhere) about the following?
I'd like %hist to output line numbers by default without having to remember the -n and without having to set up an alias every time.
How do I set %automagic to "off" by default to stop IPython polluting my namespace with its un-percented magics and shell commands? I know I can use the --no-import-all option with --pylab option: is there an equivalent --no-automagic option?
It drives me mad that I'm never quite sure what is the status of the objects bound to my variable names: changing and running a cell beneath the one I'm using can alter an object I'm referring to in the current cell. To avoid this, I've got into the habit of using Run All or Run All Above, but that sometimes repeats lengthy calculations and reimports stuff I'd rather not bother with: can I flag some cells to be not-rerun by Run All?
Can I get vi-style key-bindings for editing cells?
Why does IPython notebook hang my browser if the kernel is using lots of memory? I thought they were separate processes with the kernel just reporting back its results.
(Please try to ask one question per question - SO is designed to work that way. However, I'm not feeling so mean that I'd refuse to answer)
I don't think the behaviour of %hist is configurable, sorry.
Set c.InteractiveShell.automagic = False in your config files.
There has been some discussion of a %%cache cell magic that could avoid re-running long running cells by storing values computed in that cell. It has not been implemented yet, though.
Yes: https://github.com/ivanov/ipython-vimception
It shouldn't hang just because of kernel memory use - if your code is producing a lot of output, though, that can hang the browser because adding lots of things to the DOM gums it up.
I'm working on a python project that spans across multiple files and directories. Here's my workflow:
Run main python script
Main script calls some functions in other files
Functions in other files/directories execute
In the middle of execution, there is a bug in one of the functions, but I find the bug only after the main script finishes. Sometimes, there may not be a bug, but rather some parameter that needs tweaking.
I go back and fix the bug/make the necessary tweaks and re-run the main program and this time it executes fine.
Obviously, this workflow is terribly inefficient as considerable amount of code (that runs prior to the buggy function) gets re-executed. What would be ideal is to run the program in ipython and after discovering the issue and making the necessary changes, restart from the place where the buggy function executions starts and not from the beginning. I'm not sure how to achieve this and any help would be much appreciated.
I know how to rerun lines from ipython history (%rerun) and how to ensure autoreload of changed files in ipython, but in this case, I can't really type out the lines of code into ipython. Writing unit tests may not always be feasible, so I need an alternate solution. My use case is something similar to setting a "breakpoint" and then re-executing code past the breakpoint multiple times so as to avoid re-executing the code prior to the breakpoint more than once, while ensuring that all the necessary variables (until that stage) are correctly populated. One final condition is that I may not be able to use an IDE and vim is the only editor available across all the environments I work with.
You could start writing test cases for every function and try to debug each function separately instead of the whole program/script.
There is a python unittest-module: https://docs.python.org/3.4/library/unittest.html and a lot of tutorials like (just an example): http://docs.python-guide.org/en/latest/writing/tests/
It seems annoying writing tests but thinking about test cases gives deeper understanding of "How should the function behave if...".
You could use the code module to include "breakpoints" in your code
import code
# ... later in your program add
code.interact(local=locals()) # enter python interpreter at this point (ctrl+D to continue execution)