Inside emacs I am running interpreters for several different languages (python, R, lisp, ...). When I run the interpreters through the terminal in most cases I can use the up arrow to see the last command or line of code that I entered. I no longer have this functionality when I am running the interpreters in emacs. How can I achieve this functionality?
How can I access the command history from the interpreter inside emacs?
Can I do this generally for language X?
At the moment I need to use python, so if anyone knows how to do this specifically with the python interpreter in emacs please let me know!
You can use M-p or Ctrl-up to get to the previous command. The complementary keys M-n or Ctrl-down will get you the next command in history.
Check out Emacs' manual page on the shell history ring.
AFAIS the keys are the same as in M-x shell. See menu In/Out for available keys/commands.
Related
I am teaching a class that uses VScode.
I am used to teaching using IDLE, and it is very nice for the students to be able to call their defined functions and run snippets of code in a python terminal, for debugging purposes.
In VScode, they I have been unable to do the same in a satisfactory way.
Option1: I can select all code, right click and run selection/line on terminal. This works for small snippets, but I cannot do it for the whole file (even after selecting the whole file with ctrl-A). On linux, this works, but on windows, it does not, unfortunately (and my students use windows)
Option2: I can use the debug console. This requires adding a breakpoint in one of the last lines of the file, and does not offer tab completion. It works, but is less convenient than IDLE.
Option 3: I can also add the commands to run to the bottom of the file (which is a least preferred alternative, given that is forgoes the interativity of the read-print-eval loop).
Is there any better solution? Installing a VScode extension would not be a problem.
Visual Code is just a text editor like your traditional notepad. to run and debug any kind program you need to install the particular extension for the programming language.
In your case you are using python so you need to install the extension of it. the best one is the "Python" which is developed by microsoft itself. go to your extensions manager and install this extension. right click and click "run python file in terminal" and you are all set.
this will run exactly as they run from the idle(which is default IDE provided by python itself) you can enter the arguments from the console itself. according to me this is the best way to run and debug python programs in VScode.
another way is that VScode shows which python version is installed on your computer on the left bottom side, click on it and the programs will use this interpreter.
out of all the ways listed here and many others, the best method is to run the program in the terminal which is the recommend by python itself and many other programmers.
this method is very simple. what you have to do is open up your command prompt and type the path where python.exe is installed and the type the path of the your program as the argument and press enter. you are done !
ex : C:\Python27\python.exe C:\Users\Username\Desktop\my_python_script.py
You can also pass your arguments of your program in the command prompt itself.
if you do not want to type all this and then just use the solution mentioned above.
hope that your query is solved.
regards
I am new to Python, coming from a MATLAB background. I am using the Anaconda / Spyder 2.2.5 IDE. I am having trouble understanding the terminology used for the development environment. There are "interpreters", "consoles", "kernels", and "shells". Are these all specific entities, or is "interpreter" used interchangeably with "shell"? Can anyone define these for me, and tell me which ones I need to use? I am editing some scripts in the editor, using the python debugger. It seems like the interpreter (shell?) is the window that allows me to interact with my current "variable explorer" workspace.
An interpreter is simply an instance of the python executable being run by the operating system. When you call python interactively from a terminal or command prompt, you are calling the python interpreter to wait for user input and evaluate code line by line. Spyder provides a method to effectively have this same window within the IDE (plus some other features). A console (Probably IPython console?) is a heavily modified interactive interpreter designed to look and feel somewhat like mathematica, and provide a number of interactive features that speed up development. IPython Consoles are typically the method of choice when demonstrating code live to an audience. A kernel (in refrence to the console) is actually the python interpreter running in the background that evaluates code when it is sent in. This is a result of the back-end (kernel) / front-end (GUI) style of the IPython console interface. This again borrows some terminology from Mathematica. Lastly, a shell is generically any command line interface, and will likely be an instance of your computer's command line interface (terminal or cmd).
I changed two days ago to Emacs 23, which lately gave me a lot of headache, especially, as I have two Python versions installed, the older 2.7 and 3. As I generally want to start the python 3 interpreter, it would be nice if I could tell Emacs in some way to use python 3 instead of 2.7.
Besides, I could not find a module which helps to highlight python3 syntax. I am currently using python-mode.el for highlighting.
Also, if somebody had a good tip for which module would be best to show the pydoc, I would be very thankful.
Thanks in advance!
If you're using python-mode.el, you can specify the binary to be executed as an inferior process by setting the py-python-command variable, i.e.:
(setq py-python-command "python3")
Naturally, you'll need to provide the name of the binary as it exists on your system in place of "python3", if it differs. In python.el, the analogous variable to set is python-python-command.
As far as using pydoc, there are a few possibilities. First, you can simply execute help() inside the Python inferior process. If you do choose that option, you might find it useful to add the following code to your .emacs file:
(setenv "PAGER" "cat")
This is necessary because interactive pagers (e.g., less, more, most, etc.) don't work particularly well inside inferior process buffers. Second, you can install a Texinfo package containing the documentation and use Emacs's info browser (q.v., Python Programming in Emacs). Finally, if you opt to use python.el, it includes an interactive function called python-describe-symbol that can lookup pydoc help on demand (and I suspect python-mode.el should have something similar). If you search around a bit, I'm sure you can find other methods and/or third-party packages as well.
[RET] = enter or return key.
M = Meta or Alt key.
If you feel like letting Emacs do the heavy lifting for you, go through the Emacs settings dialogue to have Emacs set it automatically.
M-x customize-variable [RET] python-shell-interpreter [RET]
A new buffer should appear where you can customize the python interpreter you are using.
The field to the right of Python Shell Interpreter: will be the current interpreter your are using. In my case it was python so I changed it to python3. Then move the curer to select the Apply and Save button above and hit [RET] to make Emacs respect the new setting. Alternatively you can click the button with the mouse.
Next time you open the Emacs python interpreter, it will be using the new python you set from the setting dialogue.
After I did the following thing, I got the behavior that: when editing a Python file in emacs, C-c C-p creates a new buffer with a Python3 interpreter.
Add to your .emacs file the following:
(defcustom python-shell-interpreter "python3"
"Default Python interpreter for shell."
:type 'string
:group 'python)
The reason I tried this, was because I found
(defcustom python-shell-interpreter "python"
"Default Python interpreter for shell."
:type 'string
:group 'python)
in python.el. And I hypothesized (i) that the "python" could be substituted with "python3" and (ii) that this would override the definition in python.el.
It is likely that there are reasons why this is inelegant or heavy-handed or otherwise bad. I am an emacs newb.
start an python-interpreter
M-x python RET
(the default interpreter)
M-x pythonVERSION
where VERSION means any installed version
Inspired by #serv-inc's answer you can also put
(setq python-shell-interpreter "python3")
into your ./.emacs.d/init.el or where you store your configuration.
It's December 2020, I'm using EMACS 25, otherwise unconfigured for python, and I found that:
(setq python-shell-interpreter "python3")
added to my .emacs file did the business and led to a reasonably intuitive way of working with python3. C-c C-c sends my file to the interpreter (or asks me to start a new interpreter, and tells me how).
Of course, now the python3 interpreter runs for any python file, so python 2 programs don't work.
I am imagining a better world where emacs looks at the #!/usr/bin/env python2 line at the top of my file and figures out which interpreter to start by some kind of insane high-tech magic.
Note python-mode.el knows a hierarchy how to detect the version needed
a shebang precedes setting of py-shell-name
while py-execute-THING-PYTHONVERSION
would precede also shebang for the command being
see menu PyExec
I just downloaded GNU emacs23.4, and I already have python3.2 installed in Windows7.
I have been using Python IDLE to edit python files.
The problem is that I can edit python files with Emacs but I do not know how to run python interpreter in Emacs. When i click on "switch to interpreter", then it says "Searching for program: no such file or directory, python"
Someone says i need to make some change on .emacs file, but i do not know where to look for.
And I am very unexperienced and just started to learn programming. I am not familiar with commonly used terminologies. I have been searching for solutions but most of the articles i find on the Internet only confuse me.
so the questions are:
how do i run python interpreter in Emacs?
are there different kind of python interpreter? if so, why do they have different interpreters for one language?
Place this in your .emacs file to set the location of your python interpreter:
(setq python-shell-interpreter "path\to\your\python3.2")
Emacs comes with good manuals and an info mode to help read them. To learn more about .emacs you can use:
M-: (info "(Emacs)Init file") RET.
C-c C-z can do this. It is the key-binding for the command python-switch-to-python
In emacs 25.3.1 I use this to open up a python shell:
M-x run-python
After first adding this to my .emacs file:
(setq python-shell-interpreter "/usr/local/bin/python3")
IF you have python installed, try M-x python-shell
(press and hold ALT while pressing x, then type python-shell, then press enter)
There are different language implementations if that is what you are asking (see a list of them here).
In emacs 24.5.1 with spacemacs 105 (develop branch) and the Python layer enabled ("layer" is a spacemacs concept; see their documentation), I find python-shell-switch-to-shell opens an IPython buffer. I tested macropy.console in such a buffer and it works great.
You probably need to have Python in your windows PATH environment variable. Can you start the interpreter just by typing python in the command window?
I don't have anything special in my emacs.el, but the start interpreter command works just fine.
Also, I recommend reading this blog post, as it contains many useful tips and packages worth installing if using Emacs as a Python IDE.
To simply open an interpreter, you can also use M-x python. If that does not work, try M-x python and hit TAB, which will list more options via auto-completion. One of them should work k if you have python installed.
If you are inclined, it may be worthwhile to check out the Emacs python modes as well - http://www.emacswiki.org/emacs/?action=browse;oldid=PythonMode;id=PythonProgrammingInEmacs
In emacs 24.2 there is python-switch-to-python
I'm using emacs for python, and I'd like to have a nice useable shell in emacs to run an interpreter alongside my editing.
Is there any better emacs shell package out there? The default shell is awful.
You say "terminal" in the title and "shell" in the question, yet you refer to an interpreter. It's all rather confusing.
If you want a better Python interpreter than the standard (although I'd suggest you explore the features of python-mode first); check out ipython.el which will give you an IPython interface.
If you want a better terminal, try M-x ansi-term, which will give you colors, etc.
If you want a better shell, are you using eshell? You can use your standard shell with M-x shell or M-x ansi-term as above.
That depends on what shell you are using, in GNU Emacs 23 there are at least 3 built in:
shell - ugly, not working tab
eshell - not ugly but tab not working
term - not ugly and seems like ipython works with all goodies in it
So you might want to try the term mode.
Check out Gabriel Elanaro's collection of extensions to emacs for python on github.
In order to avoid future confusion between shell, terms and interpreters in Emacs, it might be worth reading this article first.