模拟Python交互模式

Question

Im writing a private online Python interpreter for VK , which would closely simulate IDLE console. Only me and some people in whitelist would be able to use this feature, no unsafe code which can harm my server. But I have a little problem. For example, I send the string with code def foo(): , and I dont want to get SyntaxError but continue defining function line by line without writing long strings with use of \\n . exec() and eval() doesn't suit me in that case. What should I use to get desired effect? Sorry if duplicate, still dont get it from similar questions.

Answer 1

It boils down to reading input, then

exec <code> in globals,locals

in an infinite loop.

See eg IPython.frontend.terminal.console.interactiveshell.TerminalInteractiveSh ell.mainloop() .

Continuation detection is done in inputsplitter.push_accepts_more() by trying ast.parse() .

Actually, IPython already has an interactive web console called Jupyter Notebook , so your best bet should be to reuse it.

Answer 2

The Python standard library provides the code and codeop modules to help you with this. The code module just straight-up simulates the standard interactive interpreter:

import code
code.interact()

It also provides a few facilities for more detailed control and customization of how it works.

If you want to build things up from more basic components, the codeop module provides a command compiler that remembers __future__ statements and recognizes incomplete commands:

import codeop
compiler = codeop.CommandCompiler()

try:
    codeobject = compiler(some_source_string)
    # codeobject is an exec-utable code object if some_source_string was a
    # complete command, or None if the command is incomplete.
except (SyntaxError, OverflowError, ValueError):
    # If some_source_string is invalid, we end up here.
    # OverflowError and ValueError can occur in some cases involving invalid literals.