CODEWITHSUNDEEP
pythonfunctionimport
user2137452
user2137452

Reputation: 145

Importing code from a file as a function in python

Essentially I have a script in one file which I would like to import and run as a function in another file. Here is the catch, the contents of the first file CANNOT be written as function definition it just needs to be a plain old script (I'm writing a simulator for my robotics kit so user experience is important). I have no idea how to go about this.

Adam

Upvotes: 0

Views: 68

Answers (2)

Tony Suffolk 66
Tony Suffolk 66

Reputation: 9704

Assuming that the code in the file you need to import is a well bounded script - then you can read in as a text variable and use the "execfile" function to create a function from that script.

By well bounded I mean that you understand all the data it needs and you are able to provide all of it from your program.

An alternative would be to use the "system" call, or the subprocess module to call the script as if it was an external program (depending if you need the script output).

A final approach will be to use exec to create a function - see approach 3.

The approach you use determines what you need your other script to do ..

examples : hello.py (your file you want to run, but can't change):

# Silly example to illustrate a script which does something.
fp = open("hello.txt", "a")
fp.write("Hello World !!!\n")
fp.close()

Three approaches to use hello.py without importing hello.py import os

print "approach 1 - using system"
os.system("python hello.py")

print "approach 2 - using execfile"
execfile("hello.py", globals(), locals())

print "approach 3 - exec to create a function"

# read script into string and indent
with open("hello.py","r") as hfp:
     hsrc = ["    " + line for line in hfp]
# insert def line
hsrc.insert(0, "def func_hello():")

# execute our function definition
exec "\n".join( hsrc) in globals(), locals()

# you now have a function called func_hello, which you can call just like a normal function

func_hello()
func_hello()

print "My original script is still running"

Upvotes: 1

Daniel Roseman
Daniel Roseman

Reputation: 599490

Anything can be written as a function.

If you additionally need the ability to call your script directly, you just use the __name__ == '__main__' trick:

def my_function():
    ... code goes here ...

if __name__ == '__main__':
    my_function()

Now you can import my_function from the rest of your code, but still execute the file directly since the block at the end will call the function.

Upvotes: 1

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