如果存在IPython，则将IPython与代码模块互换使用

Question

In an existing code snippet, I have

import sys
from code import InteractiveConsole


class FileCacher:
    "Cache the stdout text so we can analyze it before returning it"
    def __init__(self):
        self.reset()

    def reset(self):
        self.out = []

    def write(self, line):
        self.out.append(line)

    def flush(self):
        output = '\n'.join(self.out)
        self.reset()
        return output


class Shell(InteractiveConsole):
    "Wrapper around Python that can filter input/output to the shell"
    def __init__(self):
        self.stdout = sys.stdout
        self.cache = FileCacher()
        InteractiveConsole.__init__(self)
        return

    def get_output(self):
        sys.stdout = self.cache

    def return_output(self):
        sys.stdout = self.stdout

    def push(self, line):
        self.get_output()
        # you can filter input here by doing something like
        # line = filter(line)
        InteractiveConsole.push(self, line)
        self.return_output()
        output = self.cache.flush()
        # you can filter the output here by doing something like
        # output = filter(output)
        print output  # or do something else with it
        return

if __name__ == '__main__':
    sh = Shell()
    sh.interact()

How do I modify this to use IPython's interactive shell if IPython is available without changing the rest of the code if possible.

I attempted swapping out line 2 from code import InteractiveConsole with from IPython.core import interactiveshell as InteractiveConsole but obviously, it's not a directly interchangeable class.

What's the best way to do this (with minimal change to the rest of the code base) with a try except and using IPython in preference over code module when IPython exists?

Answer 1

Here's my own attempt:-

import sys
from code import InteractiveConsole

class FileCacher:
    "Cache the stdout text so we can analyze it before returning it"
    def __init__(self):
        self.reset()

    def reset(self):
        self.out = []

    def write(self, line):
        self.out.append(line)

    def flush(self):
        output = '\n'.join(self.out)
        self.reset()
        return output


class Shell(InteractiveConsole):
    "Wrapper around Python that can filter input/output to the shell"
    def __init__(self):
        self.stdout = sys.stdout
        self.cache = FileCacher()
        InteractiveConsole.__init__(self)
        return

    def get_output(self):
        sys.stdout = self.cache

    def return_output(self):
        sys.stdout = self.stdout

    def push(self, line):
        self.get_output()
        # you can filter input here by doing something like
        # line = filter(line)
        InteractiveConsole.push(self, line)
        self.return_output()
        output = self.cache.flush()
        # you can filter the output here by doing something like
        # output = filter(output)
        print output  # or do something else with it
        return

if __name__ == '__main__':
    try:
        import IPython
        IPython.embed()
    except:
        sh = Shell()
        sh.interact()

which seems to work fine but I probably lost the cache and stdout custom methods/functionalities.

Any criticism, edits and improvement suggestions welcome!

Answer 2

I'm not a big expert (so plese don't downvote if I'm wrong), but I think you can go with something like

try: from IPython.core import interactiveshell as InteractiveConsole #facade code here, if needed except ImportError: from code import InteractiveConsole #fallback case

This way you'll get your code.InteractiveConsole if it's present and IPython.core.interactiveshell otherwise remapped as InteractiveConsole . You'll have to change method names and signatures anyway, or try build some kind of facade or adapter.

One possible way is to alias all required function calls into your namespace and use this aliases. Than in 'facade' code you'll just have to define functions with same signatures (names and parameter lists) and make them call interactiveshell functions:

try:
     from IPython.core import interactiveshell as InteractiveConsole
     def func1(a,b,c):
          InteractiveConsole.some_other_func(a,b,c)
except ImportError:
     from code import InteractiveConsole        #fallback case
     func1 = InteractiveConsole.func1

...
func1(a,b,c)