I am writing an interpreter in Python where the user has to type Prolog code and I'd like to implement dynamic syntax highlighting. So far my application (which should be cross-platform) is reading input and printing from/to the command prompt (on Windows). I've been looking at the pygments library, but I have no clue on how to modify the current line (being typed) on the command prompt.
So, I've also been looking at the curses library to implement an UI but that would leave Windows users out. Any suggestions? I just need to implement a quick UI to be able to dynamically highlight what is being typed.
It appears that you can't wait for a return. To deal with input one char at a time you need something like getch.
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When reading a book or just coding on terminal/IDLE it's common to make typo, forgot brace or comma etc. After I got error and all what I wrote before is lost.
Then I have to write down code again..
Is there any way/option to return back all what write before and just edit mistake and continue to code?
In Idle (at least my version, Python 2.7.10 on windows), you can simply copy paste your code. In the python interpreter, you can't afaik, however you can use the up/down arrow keys to recall lines you previously "submitted" (i.e. typed and pressed enter).
If I understood correctly, IDLE is a GUI (graphical user interface - a visual representation of a program rather just through text) made to have a bit more features for programming in Python. You can use IDLE interactively, like in Terminal (a.k.a command line), or use it to write your script rather than in a separate text editor. Then once you save your script/program you can do neat things like run it directly from IDLE. There's nothing more special about the Terminal, you just have to do some more work.
Furthermore, all the code you have written on your GUI is on the cache memory which is used in system to store information recently accessed by a processor. So, I suggest you write again your code you can't recover them without saving.
To avoid these kind of problems use Git!
Git is a version control system that is used for software development and other version control tasks.
IDLE's Shell window is statement rather that line oriented. One can edit any line of a statement before submitting it for execution. After executing, one may recall any statement by either a) placing the cursor anywhere on the statement and hitting Enter, or b) using the history-next and history-prev actions. On Windows, these are bound, by default, to Alt-p and Alt-p. To check on your installation, Select Options => IDLE preferences on the menu. In the dialog, select the Keys tab. Under Custom Key Bindings, find the 'histor-xyz' actions in the alphabetical list.
For short, one-off scripts, I have a scratch file called tem.py. Since I use it often, it is usually accessible via File => Recent files.
I've done a bit of research and I've played with different graphical kits and was wondering if there was a way to display a native windows command line in my application. So, it'd be something like the command line in Jetbrains products (I think eclipse has one too), but the goal is to have 4 of them.
I've found a piece of linux software demonstrating the core concept of what I want to do and I've attached it at the bottom. Basically, I just want four terminals, and I'm going to have the app handle specific key bindings for "ease of access" tasks. I've used the linked software before and like it, but I thought as I'm exploring python it'd be a good learning experience to write something like this for windows as well!
Thanks in advance!
Edit - Google searching "Windows Tkinter Command Line" and the likes haven't been fruitful :) I promise I googled a LOT before posting here.
I dont know if there is anything readymade for this. Basically, you will need to have a text widget and simulate the output with the subprocess module to directly pass user input to run system commands and append results to the same text widget. You could also consider two windows - one for text input and one for result output.
Here is a link: Calling an external command in Python
I am in the works of creating a python program similar to this
. Anyway what i want to do is have users be able to modify there own programs but i need help understanding how this works. I have looked through the source code and am confused where this happens even if someone could just point me towards that that would be very helpful. I know that the programs will not be sandboxed but that is not something im worried about at the moment. If you could point me in any direction that would be great! Thank you!
The "robot programs" are just stored as plain text files.
There's a general-purpose text editor in editor.py. When you open a robot in a given view, e.g., the Qt4 view in qt4view.py, it just instantiates a text editor and hands it the robot's file. Again, the fact that the robot's file is a Python script doesn't matter; it just edits it as a text file.
The battle code, meanwhile, opens the same robot files as Python code that the text editor opens as text files. You can see this code in game.py: It just uses the subprocess module to run Python, passing the robot file as an argument.
My other answer deals with what you actually asked. But I don't think it's what you really wanted to know.
You just want to know how to run some Python script, that you've got a pathname for, in a separate Python interpreter, right?
While it's possible to figure that out from the pybotwar code, there's a whole lot of extra stuff that will get in the way of understanding it—the conf.py file, the configurable extra flags, etc.
But the answer is simple: Use the subprocess module, just as you would for running any program. In this case, the Python interpreter is the executable (usually you want sys.executable, the same Python interpreter you're using), and the script you want to run as an argument. For example:
script_output = subprocess.check_output([sys.executable, script_path])
The subprocess documentation explains all the different options very nicely.
I would like to be able to change characters as the user types text into a (cmd.Cmd) prompt using the cmd python module. So when a user types in a character I would like to be able to process that character and change it in line. Is there a way to use the cmd module to process and replace every character as it is typed or is there another module that I should be using?
edit: This is for running in a Windows environment.
It seems that you are searching to hook keyboard strokes on windows using python. if i am not mistaken in my assumption, hooking is not trivial on python since dll is required.
you may try pyHook, it uses Windows API to do the job.
Here is the API.
I don't see any way to do this with cmd.Cmd either but it would be possible with curses - see Curses Programming with Python. The getch() function will return the keycode but not echo it unless curses has been told to echo() it. That would let you take the keycode and transform it however you liked (e.g. into an 'X' to hide the characters entered as a password) before displaying the character(s) on the screen.
Alternatively, though I haven't used it, the Console module seems to provide equivalent functionality for Python on Windows.
im willing to create a project same as JUNOS cli or cisco cli,
I came through gnu readline, but im confused as there are too many functions and methods to implement. any how i want a cli with auto complete using tab and space bar with question mark to display commands with help text.
I have two questions :
I have found code in python and perl but the im not use to python that code is complete and i just want to know if i should continue with python. im more experienced in perl but the code i found so far isn't complete for perl.
readline.parse_and_bind('tab: complete')
should i use the same complete function for both help and autocomplete feature. where as i have gone through another function
readline.set_completion_display_matches_hook(print_suggestions)
what you suggest :P im completely new to it!
I must say that I struggle to understand which specific point you are addressing in your question. But here is a suggestion anyway:
Start out with the cmd module. It gives you a nice little framework to build a command-line interpreter. It supports tab completion out of the box (provided readline is available). Start implementing your command-line interface. Once this stabilizes you can think about adding more comfort, e.g. tab completion for command arguments, help keys, and the like. This way, you have a working app to deal with, and can address readline details more specifically when you really need them. I wouldn't wade through the whole readline API upfront, if I were in your shoes.
We had to create a cli like JunOS/Cisco/VyOS and we built it on top of ishell, which uses readline for this job.
From the project page:
ishell helps you to easily create an interactive shell for your application. It supports command completion, dynamic arguments, a command history, and chaining of commands.
You can check the project at github: https://github.com/italorossi/ishell
Cisco example:
PS: I'm the author :).