Is there a way to programmatically force a Python script to drop into a REPL at an arbitrary point in its execution, even if the script was launched from the command line?
I'm writing a quick and dirty plotting program, which I want to read data from stdin or a file, plot it, and then drop into the REPL to allow for the plot to be customized.
I frequently use this:
def interact():
import code
code.InteractiveConsole(locals=globals()).interact()
You could try using the interactive option for python:
python -i program.py
This will execute the code in program.py, then go to the REPL. Anything you define or import in the top level of program.py will be available.
Here's how you should do it (IPython > v0.11):
import IPython
IPython.embed()
For IPython <= v0.11:
from IPython.Shell import IPShellEmbed
ipshell = IPShellEmbed()
ipshell() # this call anywhere in your program will start IPython
You should use IPython, the Cadillac of Python REPLs. See http://ipython.org/ipython-doc/stable/interactive/reference.html#embedding-ipython
From the documentation:
It can also be useful in scientific
computing situations where it is
common to need to do some automatic,
computationally intensive part and
then stop to look at data, plots, etc.
Opening an IPython instance will give
you full access to your data and
functions, and you can resume program
execution once you are done with the
interactive part (perhaps to stop
again later, as many times as needed).
You can launch the debugger:
import pdb;pdb.set_trace()
Not sure what you want the REPL for, but the debugger is very similar.
To get use of iPython and functionality of debugger you should use ipdb,
You can use it in the same way as pdb, with the addition of :
import ipdb
ipdb.set_trace()
I just did this in one of my own scripts (it runs inside an automation framework that is a huge PITA to instrument):
x = 0 # exit loop counter
while x == 0:
user_input = raw_input("Please enter a command, or press q to quit: ")
if user_input[0] == "q":
x = 1
else:
try:
print eval(user_input)
except:
print "I can't do that, Dave."
continue
Just place this wherever you want a breakpoint, and you can check the state using the same syntax as the python interpreter (although it doesn't seem to let you do module imports).
It's not very elegant, but it doesn't require any other setup.
Great answers above, but if you would like this functionality in your IDE. Using Visual Studio Code (v1.5.*) with Python Setup:
Highlight the lines you would like to run and
right click and select Run Selection/Line in Interactive Window from the drop down.
Press shift + enter on your keyboard.
Right click on the Python file you want to execute in the file explorer and select Run Current File in Interactive Window
This will launch an interactive session, with linting, code completion and syntax highlighting:
Enter the code you would like to evaluate, and hit shift + enter on your keyboard to execute.
Enjoy Python!
Related
I use Linux. I want to hide the terminal, that is, that the command is executed in Python but invisible.
Try with two method that do not work on me (maybe I do not do it well), but I want to know if there are others. What I tried was .pyw and nohup
A quick example of the code to test is:
import time
import os
x = 1
While x == 1:
os.system(f"mpg321 /beep.mp3")
time.sleep(20)
I'm just getting started with Python and trying to get some easy code-examples to compile. I am using the 'Spyder' Editor and everytime I run code it shows 'runfile(...)' before the actual compiled code in the console.
Is there a way to prevent this behaviour?
Try including this instead immediately prior to your code. The terminal will now return a clean code only response:
cls = lambda: print("\033[2J\033[;H", end='')
cls()
you are trying to run the code, instead go to settings, keyboard shortcuts, and look for "run selection" it will have a shortcut assigned to it
Now select all the code and use the shortcut
it will only give you in and out
Is there a way to programmatically force a Python script to drop into a REPL at an arbitrary point in its execution, even if the script was launched from the command line?
I'm writing a quick and dirty plotting program, which I want to read data from stdin or a file, plot it, and then drop into the REPL to allow for the plot to be customized.
I frequently use this:
def interact():
import code
code.InteractiveConsole(locals=globals()).interact()
You could try using the interactive option for python:
python -i program.py
This will execute the code in program.py, then go to the REPL. Anything you define or import in the top level of program.py will be available.
Here's how you should do it (IPython > v0.11):
import IPython
IPython.embed()
For IPython <= v0.11:
from IPython.Shell import IPShellEmbed
ipshell = IPShellEmbed()
ipshell() # this call anywhere in your program will start IPython
You should use IPython, the Cadillac of Python REPLs. See http://ipython.org/ipython-doc/stable/interactive/reference.html#embedding-ipython
From the documentation:
It can also be useful in scientific
computing situations where it is
common to need to do some automatic,
computationally intensive part and
then stop to look at data, plots, etc.
Opening an IPython instance will give
you full access to your data and
functions, and you can resume program
execution once you are done with the
interactive part (perhaps to stop
again later, as many times as needed).
You can launch the debugger:
import pdb;pdb.set_trace()
Not sure what you want the REPL for, but the debugger is very similar.
To get use of iPython and functionality of debugger you should use ipdb,
You can use it in the same way as pdb, with the addition of :
import ipdb
ipdb.set_trace()
I just did this in one of my own scripts (it runs inside an automation framework that is a huge PITA to instrument):
x = 0 # exit loop counter
while x == 0:
user_input = raw_input("Please enter a command, or press q to quit: ")
if user_input[0] == "q":
x = 1
else:
try:
print eval(user_input)
except:
print "I can't do that, Dave."
continue
Just place this wherever you want a breakpoint, and you can check the state using the same syntax as the python interpreter (although it doesn't seem to let you do module imports).
It's not very elegant, but it doesn't require any other setup.
Great answers above, but if you would like this functionality in your IDE. Using Visual Studio Code (v1.5.*) with Python Setup:
Highlight the lines you would like to run and
right click and select Run Selection/Line in Interactive Window from the drop down.
Press shift + enter on your keyboard.
Right click on the Python file you want to execute in the file explorer and select Run Current File in Interactive Window
This will launch an interactive session, with linting, code completion and syntax highlighting:
Enter the code you would like to evaluate, and hit shift + enter on your keyboard to execute.
Enjoy Python!
Is there a way in Python to detect, within a process, where that process is being executed? I have some code that includes the getpass.getpass() function, which is broken in Spyder, and it's annoying to go back and forth between the command line and the IDE all the time. It would be useful if I could add code like:
if not being run from Spyder:
use getpass
else:
use alternative
Here is the solution I ended up using. After reading Markus's answer, I noticed that Spyder adds half a dozen or so environment variables to os.environ with names like SPYDER_ENCODING, SPYDER_SHELL_ID, etc. Detecting the presence of any of these seems relatively unambiguous, compared to detecting the absence of a variable with as generic a name as 'PYTHONSTARTUP'. The code is simple, and works independently of Spyder's startup script (as far as I can tell):
if any('SPYDER' in name for name in os.environ)
# use alternative
else:
# use getpass
Since the string is at the beginning of each environment variable name, you could also use str.startswith, but it's less flexible, and a little bit slower (I was curious):
>>> import timeit
>>> s = timeit.Timer("[name.startswith('SPYDER') for name in os.environ]", "import os")
>>> i = timeit.Timer("['SPYDER' in name for name in os.environ]", "import os")
>>> s.timeit()
16.18333065883474
>>> i.timeit()
6.156869294143846
The sys.executable method may or may not be useful depending on your installation. I have a couple WinPython installations and a separate Python 2.7 installation, so I was able to check the condition sys.executable.find('WinPy') == -1 to detect a folder name in the path of the executable Spyder uses. Since the warning that shows in IDLE when you try to use getpass is less "loud" than it could be, in my opinion, I ended up also checking the condition sys.executable.find('pythonw.exe') == -1 to make it slightly louder. Using sys.executable only, that method looks like:
if sys.executable.find('pythonw.exe') == sys.executable.find('WinPy') == -1:
# use getpass
else:
# use alternative
But since I want this to work on other machines, and it's much more likely that another user would modify their WinPython installation folder name than that they would rename their IDLE executable, my final code uses sys.executable to detect IDLE and os.environ to detect Spyder, providing a "louder" warning in either case and keeping the code from breaking in the latter.
if any('SPYDER' in name for name in os.environ) \
or 'pythonw.exe' in sys.executable:
password = raw_input('WARNING: PASSWORD WILL BE SHOWN ON SCREEN\n\n' * 3
+ 'Please enter your password: ')
else:
password = getpass.getpass("Please enter your password: ")
By default, Spyder uses a startup scrip, see Preferences -> Console -> Adanced setting. This option is usually set to the scientific_startup.py file that loads pylab et al.
The easiest solution is to just add a global variable to the file and then use that in your if statement, e.g. add this line at the end of scientific_startup.py:
SPYDER_IDE_ACTIVE = True
In your script:
if not 'SPYDER_IDE_ACTIVE' in globals():
use getpass
else:
use alternative
This will work without throwing an error. You can also use exceptions if you like that more.
A second solution would be (if you cannot modify that file for some reason) to just check if the environment variable PYTHONSTARTUP is set. On my machine (using the Anaconda Python stack), it is not set for a regular Python shell. You could do
import os
if not 'PYTHONSTARTUP' in os.environ:
use getpass
else:
use alternative
Spyder provides the option of executing the current editor script in a native system terminal. This would produce identical behavior as if you were running from the command line. To set this up, open the Run Settings dialog by hitting F6. Then select the radio button "Execute in an external System terminal". Now run the script as usual by hitting F5. You should be able to use getpass in the normal fashion with this approach.
You could add env variable when running in Spyder and check it in code.
I'm trying to save myself just a few keystrokes for a command I type fairly regularly in Python.
In my python startup script, I define a function called load which is similar to import, but adds some functionality. It takes a single string:
def load(s):
# Do some stuff
return something
In order to call this function I have to type
>>> load('something')
I would rather be able to simply type:
>>> load something
I am running Python with readline support, so I know there exists some programmability there, but I don't know if this sort of thing is possible using it.
I attempted to get around this by using the InteractivConsole and creating an instance of it in my startup file, like so:
import code, re, traceback
class LoadingInteractiveConsole(code.InteractiveConsole):
def raw_input(self, prompt = ""):
s = raw_input(prompt)
match = re.match('^load\s+(.+)', s)
if match:
module = match.group(1)
try:
load(module)
print "Loaded " + module
except ImportError:
traceback.print_exc()
return ''
else:
return s
console = LoadingInteractiveConsole()
console.interact("")
This works with the caveat that I have to hit Ctrl-D twice to exit the python interpreter: once to get out of my custom console, once to get out of the real one.
Is there a way to do this without writing a custom C program and embedding the interpreter into it?
Edit
Out of channel, I had the suggestion of appending this to the end of my startup file:
import sys
sys.exit()
It works well enough, but I'm still interested in alternative solutions.
You could try ipython - which gives a python shell which does allow many things including automatic parentheses which gives you the function call as you requested.
I think you want the cmd module.
See a tutorial here:
http://wiki.python.org/moin/CmdModule
Hate to answer my own question, but there hasn't been an answer that works for all the versions of Python I use. Aside from the solution I posted in my question edit (which is what I'm now using), here's another:
Edit .bashrc to contain the following lines:
alias python3='python3 ~/py/shellreplace.py'
alias python='python ~/py/shellreplace.py'
alias python27='python27 ~/py/shellreplace.py'
Then simply move all of the LoadingInteractiveConsole code into the file ~/py/shellreplace.py Once the script finishes executing, python will cease executing, and the improved interactive session will be seamless.