python交互模式热加载究极实现方式

拼搏现实的明天。 2023-07-18 09:44 16阅读 0赞

之前写了一个热加载的python shell模式，但是不能支持多行，于是我就直接去看了python code模块的源码，然后扒下来，自己加上文件检测的函数，就成了一个可以热加载的python shell模式

创建一个 py\_code.py 文件

"""Utilities needed to emulate Python's interactive interpreter.
    
    """
    
    # Inspired by similar code by Jeff Epler and Fredrik Lundh.
    
    import sys, os, importlib
    import traceback
    from codeop import CommandCompiler, compile_command
    
    __all__ = ["InteractiveInterpreter", "InteractiveConsole", "interact",
               "compile_command"]
    
    class InteractiveInterpreter:
        """Base class for InteractiveConsole.
    
        This class deals with parsing and interpreter state (the user's
        namespace); it doesn't deal with input buffering or prompting or
        input file naming (the filename is always passed in explicitly).
    
        """
    
        def __init__(self, locals=None):
            """Constructor.
    
            The optional 'locals' argument specifies the dictionary in
            which code will be executed; it defaults to a newly created
            dictionary with key "__name__" set to "__console__" and key
            "__doc__" set to None.
    
            """
            if locals is None:
                locals = {"__name__": "__console__", "__doc__": None}
            self.locals = locals
            self.compile = CommandCompiler()
    
        def runsource(self, source, filename="<input>", symbol="single"):
            """Compile and run some source in the interpreter.
    
            Arguments are as for compile_command().
    
            One several things can happen:
    
            1) The input is incorrect; compile_command() raised an
            exception (SyntaxError or OverflowError).  A syntax traceback
            will be printed by calling the showsyntaxerror() method.
    
            2) The input is incomplete, and more input is required;
            compile_command() returned None.  Nothing happens.
    
            3) The input is complete; compile_command() returned a code
            object.  The code is executed by calling self.runcode() (which
            also handles run-time exceptions, except for SystemExit).
    
            The return value is True in case 2, False in the other cases (unless
            an exception is raised).  The return value can be used to
            decide whether to use sys.ps1 or sys.ps2 to prompt the next
            line.
    
            """
            try:
                code = self.compile(source, filename, symbol)
            except (OverflowError, SyntaxError, ValueError):
                # Case 1
                self.showsyntaxerror(filename)
                return False
    
            if code is None:
                # Case 2
                return True
    
            # Case 3
            self.runcode(code)
            return False
    
        def runcode(self, code):
            """Execute a code object.
    
            When an exception occurs, self.showtraceback() is called to
            display a traceback.  All exceptions are caught except
            SystemExit, which is reraised.
    
            A note about KeyboardInterrupt: this exception may occur
            elsewhere in this code, and may not always be caught.  The
            caller should be prepared to deal with it.
    
            """
            try:
                exec(code, self.locals)
            except SystemExit:
                raise
            except:
                self.showtraceback()
    
        def showsyntaxerror(self, filename=None):
            """Display the syntax error that just occurred.
    
            This doesn't display a stack trace because there isn't one.
    
            If a filename is given, it is stuffed in the exception instead
            of what was there before (because Python's parser always uses
            "<string>" when reading from a string).
    
            The output is written by self.write(), below.
    
            """
            type, value, tb = sys.exc_info()
            sys.last_type = type
            sys.last_value = value
            sys.last_traceback = tb
            if filename and type is SyntaxError:
                # Work hard to stuff the correct filename in the exception
                try:
                    msg, (dummy_filename, lineno, offset, line) = value.args
                except ValueError:
                    # Not the format we expect; leave it alone
                    pass
                else:
                    # Stuff in the right filename
                    value = SyntaxError(msg, (filename, lineno, offset, line))
                    sys.last_value = value
            if sys.excepthook is sys.__excepthook__:
                lines = traceback.format_exception_only(type, value)
                self.write(''.join(lines))
            else:
                # If someone has set sys.excepthook, we let that take precedence
                # over self.write
                sys.excepthook(type, value, tb)
    
        def showtraceback(self):
            """Display the exception that just occurred.
    
            We remove the first stack item because it is our own code.
    
            The output is written by self.write(), below.
    
            """
            sys.last_type, sys.last_value, last_tb = ei = sys.exc_info()
            sys.last_traceback = last_tb
            try:
                lines = traceback.format_exception(ei[0], ei[1], last_tb.tb_next)
                if sys.excepthook is sys.__excepthook__:
                    self.write(''.join(lines))
                else:
                    # If someone has set sys.excepthook, we let that take precedence
                    # over self.write
                    sys.excepthook(ei[0], ei[1], last_tb)
            finally:
                last_tb = ei = None
    
        def write(self, data):
            """Write a string.
    
            The base implementation writes to sys.stderr; a subclass may
            replace this with a different implementation.
    
            """
            sys.stderr.write(data)
    
    
    class InteractiveConsole(InteractiveInterpreter):
        """Closely emulate the behavior of the interactive Python interpreter.
    
        This class builds on InteractiveInterpreter and adds prompting
        using the familiar sys.ps1 and sys.ps2, and input buffering.
    
        """
    
        def __init__(self, locals=None, filename="<console>"):
            """Constructor.
    
            The optional locals argument will be passed to the
            InteractiveInterpreter base class.
    
            The optional filename argument should specify the (file)name
            of the input stream; it will show up in tracebacks.
    
            """
            InteractiveInterpreter.__init__(self, locals)
            self.filename = filename
            self.resetbuffer()
    
        # 自己加的函数
        def iteration_module_files(self):
            # 获取环境
            for module in sys.modules.values():
                filename = getattr(module, '__file__', None)
                if filename:
                    # 减少判断只检测本目录下的模块
                    if not os.getcwd() in filename:
                        continue
                    if filename[-4:] in ('.pyo', '.pyc'):
                        filename = filename[:-1]
                    # 将模块也带过去，因为后面需要重载被修改文件的模块
                    yield (filename, module)
    
        # 自己加的函数
        def is_files_modify(self, mtimes, module_list):
            # 检测模块文件是否修改
            for filename, module in self.iteration_module_files():
                try:
                    # 文件修改时间
                    mtime = os.stat(filename).st_mtime
                except IOError:
                    continue
                # 从dict中根据文件名取出上一次文件修改时间
                old_time = mtimes.get(filename, None)
                # 如果没有上一次的修改时间，加入dict
                if old_time is None:
                    mtimes[filename] = mtime
                # 对比修改时间
                elif mtime > old_time:
                    # 将修改了时间的模块加入列表
                    module_list.add(module)
                    # 如果不把新的时间赋值给文件，那么会一直进入重载
                    mtimes[filename] = mtime
            return module_list
    
        def resetbuffer(self):
            """Reset the input buffer."""
            self.buffer = []
    
        def interact(self, banner=None, exitmsg=None):
            """Closely emulate the interactive Python console.
    
            The optional banner argument specifies the banner to print
            before the first interaction; by default it prints a banner
            similar to the one printed by the real Python interpreter,
            followed by the current class name in parentheses (so as not
            to confuse this with the real interpreter -- since it's so
            close!).
    
            The optional exitmsg argument specifies the exit message
            printed when exiting. Pass the empty string to suppress
            printing an exit message. If exitmsg is not given or None,
            a default message is printed.
    
            """
            try:
                sys.ps1
            except AttributeError:
                sys.ps1 = ">>> "
            try:
                sys.ps2
            except AttributeError:
                sys.ps2 = "... "
            cprt = 'Type "help", "copyright", "credits" or "license" for more information.'
            if banner is None:
                self.write("Python %s on %s\n%s\n(%s)\n" %
                           (sys.version, sys.platform, cprt,
                            self.__class__.__name__))
            elif banner:
                self.write("%s\n" % str(banner))
            more = 0
            # mtimes，module_list 自己家的变量
            mtimes = {}
            module_list = set()
            while 1:
                # ------ start ------
                # 自己加的判断
                self.is_files_modify(mtimes, module_list)
                # 如果有文件修改，就重载修改过的模块
                if module_list:
                    for module in module_list:
                        importlib.reload(module)
                        # 记得清空模块列表
                        module_list = set()
                # ------ end ----------
                try:
                    if more:
                        prompt = sys.ps2
                    else:
                        prompt = sys.ps1
                    try:
                        line = self.raw_input(prompt)
                    except EOFError:
                        self.write("\n")
                        break
                    else:
                        more = self.push(line)
                except KeyboardInterrupt:
                    self.write("\nKeyboardInterrupt\n")
                    self.resetbuffer()
                    more = 0
                    break
            if exitmsg is None:
                self.write('now exiting %s...\n' % self.__class__.__name__)
            elif exitmsg != '':
                self.write('%s\n' % exitmsg)
    
        def push(self, line):
            """Push a line to the interpreter.
    
            The line should not have a trailing newline; it may have
            internal newlines.  The line is appended to a buffer and the
            interpreter's runsource() method is called with the
            concatenated contents of the buffer as source.  If this
            indicates that the command was executed or invalid, the buffer
            is reset; otherwise, the command is incomplete, and the buffer
            is left as it was after the line was appended.  The return
            value is 1 if more input is required, 0 if the line was dealt
            with in some way (this is the same as runsource()).
    
            """
            self.buffer.append(line)
            source = "\n".join(self.buffer)
            more = self.runsource(source, self.filename)
            if not more:
                self.resetbuffer()
            return more
    
        def raw_input(self, prompt=""):
            """Write a prompt and read a line.
    
            The returned line does not include the trailing newline.
            When the user enters the EOF key sequence, EOFError is raised.
    
            The base implementation uses the built-in function
            input(); a subclass may replace this with a different
            implementation.
    
            """
            return input(prompt)
    
    
    
    def interact(banner=None, readfunc=None, local=None, exitmsg=None):
        """Closely emulate the interactive Python interpreter.
    
        This is a backwards compatible interface to the InteractiveConsole
        class.  When readfunc is not specified, it attempts to import the
        readline module to enable GNU readline if it is available.
    
        Arguments (all optional, all default to None):
    
        banner -- passed to InteractiveConsole.interact()
        readfunc -- if not None, replaces InteractiveConsole.raw_input()
        local -- passed to InteractiveInterpreter.__init__()
        exitmsg -- passed to InteractiveConsole.interact()
    
        """
        console = InteractiveConsole(local)
        if readfunc is not None:
            console.raw_input = readfunc
        else:
            try:
                import readline
            except ImportError:
                pass
        console.interact(banner, exitmsg)
    
    
    if __name__ == "__main__":
        import argparse
    
        parser = argparse.ArgumentParser()
        parser.add_argument('-q', action='store_true',
                           help="don't print version and copyright messages")
        args = parser.parse_args()
        if args.q or sys.flags.quiet:
            banner = ''
        else:
            banner = None
        interact(banner)

创建 demo01.py文件

import demo02
    
    class Demo1(object):
        def x1():
            print('this is Demo1.x1')

创建 demo02.py

class Demo2(object):
        def x2():
            print('this is Demo2.x2')

终端启动py\_code.py

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