I want to make my own programming language based on python which will provide additional features that python wasn't provide, for example to make multiline anonymous function with custom syntax. I want my programming language is so simple to be used, just import my script, then I read the script file which is imported my script, then process it's code and stop anymore execution of the script which called my script to prevent error on syntax...
Let say there are 2 py file, main.py and MyLanguage.py
The main.py imported MyLanguage.py
Then how to get the main.py file from MyLanguage.py if main.py can be another name(Dynamic Name)?
Additional information:
I using python 3.4.4 on Windows 7
Like Colonder, I believe the project you have in mind is far more difficult than you imagine.
But, to get you started, here is how to get the main.py file from inside MyLanguage.py. If your importing module looks like this
# main.py
import MyLanguage
if __name__ == "__main__":
print("Hello world from main.py")
and the module it is importing looks like this, in Python 3:
#MyLanguage.py
import inspect
def caller_discoverer():
print('Importing file is', inspect.stack()[-1].filename)
caller_discoverer()
or (edit) like this, in Python 2:
#MyLanguage.py
import inspect
def caller_discoverer():
print 'Importing file is', inspect.stack()[-1][1]
caller_discoverer()
then the output you will get when you run main.py is
Importing file is E:/..blahblahblah../StackOverflow-3.6/48034902/main.py
Hello world from main.py
I believe this answers the question you asked, though I don't think it goes very far towards achieving what you want. The reason for my scepticism is simple: the import statement expects a file containing valid Python, and if you want to import a file with your own non-Python syntax, then you are going to have to do some very clever stuff with import hooks. Without that, your program will simply fail at the import statement with a syntax error.
Best of luck.
Related
I'm trying to use multiple files in my programing and I ran into a problem.
I have two files: main.py, nu.py
The main file is:
import numpy
import nu
def numarray():
numpy.array(some code goes here)
nu.createarray()
The nu file is:
def createarray():
numpy.array(some code goes here)
When I run main I get an error:
File "D:\python\nu.py", line 2, in createarray
numpy.array(some code goes here)
NameError: name 'numpy' is not defined
numpy is just an exaple, I'm using about six imports.
As far as I see it, I have to import all moduls on all files, but it creating a problem where certain modules can't be loaded twice, it just hang.
What I'm doing wrong and how can I properly import functions from another file while using imported modules from the main file?
I hope i explain it well.
thanks for helping!
I have years in python and importing from other files is still a headache..
The problmen here is that you are not importing numpy in "nu.py".
But as you say sometimes it's a little annoying have to import al libraries in all files.
The last thing is, How do you get the error a module cannot be imported twice? can you give me an example?
In each separate python script if you are using a module within you need to import it to access. So you will need to 'import numpy' in your nu.py script like below
If possible try keeping the use of a module within a script so you dont have import the same multiple times, although this wont always be appropriate
EDIT: Solved! Solution on the bottom of this post. tl;dr: I should have been using relative imports, and launching python with the correct flag.
So I'm trying to get used to some python stuff (version 2.7.3—it's what's installed on the work PC), and I've got a little project to teach me some python stuff. I've got a module defined like so:
curses_graphics
| __init__.py
| graphicsobject.py
| go_test.py
(code to follow)
I've got a decorator defined in __init__, and I'm trying to use it on methods defined in a class in graphicsobject.py that I'm trying to attach the decorator to, and I'm testing its functionality in go_test.
When I run go_test (just being in the directory and calling "python go_test.py"), I get a no package found error. Same happens if I rename go_test to __main__.py and try to run the package from its parent directory. If I try to run the go_test without importing the package, it doesn't recognise my function.
How can I reference a function defined in __init__.py from within the same package? Is it wrong to try and import while within the package?
Thanks!
__init__.py:
import curses
import logging
#Define logging stuff
gLog = logging.getLogger("cg_log")
gLog.basicConfig(filename="log.log", level=logging.DEBUG)
# Logging decorators for this library
def debug_announce(module_func):
log=logging.getLogger("cg_log")
log.info("Curses Graphics Lib:Entering function:"+module_func.__name__)
module_func()
log.info("Curses Graphics Lib:Left function:"+module_func.__name__)
go_test.py
#debug_announce
def logTester():
print("A test method")
logTester()
logger.debug("Curses initialization")
screen=curses.initscr()
curses.start_color()
screen.keypad(True)
logger.debug("Initializing a green block filled with red '.'s")
block = GraphicsOBject.blankline(0, 0, 3, curses.COLOR_GREEN, curses.COLOR_RED, 20, '.')
logger.debug("Drawing the block.")
block.draw(screen)
logger.debug("Pausing execution with a getch")
screen.getch()
logger.debug("Cleaning up curses")
screen.keypad(False)
curses.endwin()
os.system('stty sane')
I can include graphicsobject.py, though I suspect that would be clutter here, as the issue occurs on the first line of go_test.py
Thanks, everyone!
EDIT:
I'm attaching a capture of the errors reported. In the first error, I've added "from curses_graphics import debug_announce" and in the second the code doesn't have that line.
Errors with and without debug_announce import
EDIT:
Some further searching led me to relative imports. For anyone who has my issue, you use those to import something defined in your own module. In my case, I appended "from . import debug_announce" to the head of my go_test.py file. I attempted to run it, and received the error “Attempted relative import in non-package”.
Some further searching led me to this question:
How to fix "Attempted relative import in non-package" even with __init__.py
Which told me that it wasn't attempting to run this program as a package. This meant the "__init__.py" was never running, as the package wouldn't be imported. Further, since I was inside the package, attempting to import the package (i.e. "import curses_graphics") would result in it searching inside curses_graphics... for curses_graphics.
To run this correctly, as the linked question implies, I need to go to the parent directory of curses_graphics and execute it with "python -m curses_graphics.go_test". This runs the package with its inits and such and run the script of go_test.
(And, FWIW, my code had other issues. Don't take this as an example of how to use curses or logging :P)
I have a requirement where I need to parse the functions defined in a python file from another python file.
e.g. I have a python file with following contents:
a.py
import os, sys
def function1('text'):
pass
def function2('text'):
pass
Another file is:
b.py
interested_func = 'function2'
function_list = <code to fetch the functions defined in a.py>
if interested_func in function_list:
print 'match found'
How can I get the functions from a.py into b.py so that I can compare the same with the 'interested_func' data and can do specific task based on the match.
Please note that I have 100s of files with different functions defined inside them, so I do not want to import the file.
Please help, thanks in advance!
You should probably use the importlib module:
import importlib
obj = importlib.import_module(module)
print(dir(obj))
You can read more about importlib over in the Python docs.
If that doesn't work for you, then you'll probably want to look at some static code analysis tools such as pylint that might give you a clue into how to do this sort of thing. Another place to look would be to check out PyDev's source code and see how it does code analysis.
I am working on project euler and wanted to time all of my code. What I have is directory of files in the form 'problemxxx.py' where xxx is the problem number. Each of these files has a main() function that returns the answer. So I have created a file called run.py, located in the same directory as the problem files. I am able to get the name of the file through command prompt. But when I try to import the problem file, I continue to get ImportError: No module named problem. Below is the code for run.py so far, along with the command prompt used.
# run.py
import sys
problem = sys.argv[1]
import problem # I have also tired 'from problem import main' w/ same result
# will add timeit functions later, but trying to get this to run first
problem.main()
The command prompts that I have tried are the following: (both of which give the ImportError stated above)
python run.py problem001
python run.py problem001.py
How can I import the function main() from the file problem001.py? Does importing not work with the file name stored as a variable? Is there a better solution than trying to get the file name through command prompt? Let me know if I need to add more information, and thank you for any help!
You can do this by using the __import__() function.
# run.py
import sys
problem = __import__(sys.argv[1], fromlist=["main"]) # I have also tired 'from problem import main' w/ same result
problem.main()
Then if you have problem001.py like this:
def main():
print "In sub_main"
Calling python run.py problem001 prints:
In sub_main
A cleaner way to do this (instead of the __import__ way) is to use the importlib module. Your run.py needs to changes:
import importlib
problem = importlib.import_module(sys.argv[1])
Alternatives are mentioned in this question.
For sure! You can use __ import_ built-in function like __import__(problem). However this is not recommended to use, because it is not nice in terms of coding-style. I think if you are using this for testing purposes then you should use unittest module, either way try to avoid these constructions.
Regards
You can use exec() trick:
import sys
problem = sys.argv[1]
exec('import %s' % problem)
exec('%s.main()' % problem)
If I have a Python module implemented as a directory (i.e. package) that has both a top level function run and a submodule run, can I count on from example import run to always import the function? Based on my tests that is the case at least with Python 2.6 and Jython 2.5 on Linux, but can I count on this generally? I tried to search information about the import priorities but couldn't find anything.
Background:
I have a pretty large package that people generally run as a tool from the command line but also sometimes use programmatically. I would like to have simple entry points for both usages and consider to implement them like this:
example/__init__.py:
def run(*args):
print args # real application code belongs here
example/run.py:
import sys
from example import run
run(*sys.argv[1:])
The first entry point allows users to access the module from Python like this:
from example import run
run(args)
The latter entry point allows users to execute the module from the command line using both of the approaches below:
python -m example.run args
python path/to/example/run.py args
This both works great and covers everything I need. Before taking this into real use, I would like to know is this a sound approach that I can expect to work with all Python implementations on all operating systems.
I think this should always work; the function definition will shadow the module.
However, this also strikes me as a dirty hack. The clean way to do this would be
# __init__.py
# re-export run.run as run
from .run import run
i.e., a minimal __init__.py, with all the running logic in run.py:
# run.py
def run(*args):
print args # real application code belongs here
if __name__ == "__main__":
run(*sys.argv[1:])