有没有办法以字符串形式获取上下文管理器中的源代码？

Question

函数的源代码可以通过inspect.getsourcelines(func)

函数接收。有没有办法为上下文管理器做同样的事情？

with test():
    print('123')

# How to get "print('123')" as line here?

Answer 1

您对这个解决方案有何看法？

import traceback


class ContextManagerContent(object):

    def __enter__(self):
        return

    def __exit__(self, _type, value, _traceback):
        stack = traceback.extract_stack()
        f, last_line = self._get_origin_info(stack)

        with open(f) as fin:
            lines = list(fin)

        search = 'with {cls_name}'.format(cls_name=self.__class__.__name__)
        for i, x in enumerate(lines[:last_line + 1][::-1]):
            if search in x:
                first_line = len(lines) - i
                break

        selected_lines = lines[first_line:last_line + 1]
        print ''.join(selected_lines)

    def _get_origin_info(self, stack):
        origin = None
        for i, x in enumerate(stack[::-1]):
            if x[2] == '__exit__':
                origin = stack[::-1][i + 1]
                break

        return origin[0], origin[1] - 1


with ContextManagerContent():
    print '123'
    print '456'
    print '789'

如果将其保存在

.py

 文件中并运行它，您可以看到打印数字 123、456 和 789，之后您可以看到上下文管理器的块。

请注意，我没有处理可能的异常或输出格式，并且某些部分可以改进，但我认为这是一个很好的起点。

Answer 2

这是另一个受@se7entyse7en 答案启发的解决方案。我认为这样更干净、更高效

from inspect import currentframe, getframeinfo
from contextlib import contextmanager


@contextmanager
def debug(string):
    # before block
    cf = currentframe()
    first_line =  cf.f_back.f_back.f_lineno
    filename = getframeinfo(cf.f_back.f_back).filename

    yield

    # after block
    cf = currentframe()
    last_line =  cf.f_back.f_back.f_lineno
    with open(filename) as f:
        lines = f.readlines()[first_line:last_line]
    print(string + '\n' + ''.join(lines).rstrip())


if __name__ == '__main__':
    with debug("show this code in stdout:"):
        a = 1
        b = 2
        a, b = b, a

Answer 3

现有的解决方案都不适合我，所以这是另一个实现。

import inspect, linecache
from pathlib import Path
import tempfile

class ContextCodeCapture():
    def __enter__(self):
        return self
    def __exit__(self, exc_type, exc_val, exc_tb):  
        cf = inspect.currentframe().f_back
        filename = cf.f_code.co_filename
        line = cf.f_lineno
        lines = []
        indent = 0
        i = 1
        while True:
            next_line = linecache.getline(filename, line + i)
            next_line_indent = len(next_line) - len(next_line.lstrip())
            if indent == 0:
                indent = next_line_indent
            elif (next_line_indent < indent and len(next_line.strip()) > 0) or next_line == "":
                break
            if next_line == "\n": # preserve newlines
                lines.append(next_line)
            else:
                lines.append(next_line[indent:])
            i += 1
        content = "".join(lines)
        print(content)


if __name__ == "__main__":
    with ContextCodeCapture():
        def say_hello(name):
            print(f"Hello {name}")

        foo = 2

        if True:
            for i in range(100):
                foo *= i

运行此示例将打印以下输出

def say_hello(name):
    print(f"Hello {name}")

foo = 2

if True:
    for i in range(100):
        foo *= i