Python、Quickly 和 Glade，如何在 TextView 中显示 stdout

Question

我花了很长时间寻找解决办法，但到现在为止还没有找到。 :(

我想为我做的一个小命令行程序制作一个图形界面，所以我觉得使用Ubuntu的“Quickly”是最简单的办法。基本上，它似乎是用Glade来制作图形界面的。我知道我需要在一个子进程中运行我的命令行程序，然后把输出和错误信息发送到一个文本视图中。但我就是搞不懂该怎么做。

这是Glade/Quickly为我想要显示输出的对话框生成的代码：

from gi.repository import Gtk # pylint: disable=E0611

from onice_lib.helpers import get_builder

import gettext
from gettext import gettext as _
gettext.textdomain('onice')

class BackupDialog(Gtk.Dialog):
    __gtype_name__ = "BackupDialog"

    def __new__(cls):
        """Special static method that's automatically called by Python when 
        constructing a new instance of this class.

        Returns a fully instantiated BackupDialog object.
        """
        builder = get_builder('BackupDialog')
        new_object = builder.get_object('backup_dialog')
        new_object.finish_initializing(builder)
        return new_object

    def finish_initializing(self, builder):
        """Called when we're finished initializing.

        finish_initalizing should be called after parsing the ui definition
        and creating a BackupDialog object with it in order to
        finish initializing the start of the new BackupDialog
        instance.
        """
        # Get a reference to the builder and set up the signals.
        self.builder = builder
        self.ui = builder.get_ui(self)

        self.test = False

    def on_btn_cancel_now_clicked(self, widget, data=None):
        # TODO: Send SIGTERM to the subprocess
        self.destroy()

if __name__ == "__main__":
    dialog = BackupDialog()
    dialog.show()
    Gtk.main()

如果我把这个放在finish_initializing函数里

backend_process = subprocess.Popen(["python", <path to backend>], stdout=subprocess.PIPE, shell=False)

那么这个进程就会作为另一个PID启动并运行，这正是我想要的，但现在我该怎么把backend_process.stdout发送到文本视图呢？我可以用下面的代码写入文本视图：

BackupDialog.ui.backup_output.get_buffer().insert_at_cursor("TEXT")

但我只需要知道如何在每次有新的输出行时调用这个。

Answer 1

但是我只想知道每次有新的输出行时，怎么能让这个被调用。

你可以使用 GObject.io_add_watch 来监控子进程的输出，或者创建一个单独的线程来读取子进程的内容。

# read from subprocess
def read_data(source, condition):
    line = source.readline() # might block
    if not line:
        source.close()
        return False # stop reading
    # update text
    label.set_text('Subprocess output: %r' % (line.strip(),))
    return True # continue reading
io_id = GObject.io_add_watch(proc.stdout, GObject.IO_IN, read_data)

或者使用线程：

# read from subprocess in a separate thread
def reader_thread(proc, update_text):
    with closing(proc.stdout) as file:
        for line in iter(file.readline, b''):
            # execute update_text() in GUI thread
            GObject.idle_add(update_text, 'Subprocess output: %r' % (
                    line.strip(),))

t = Thread(target=reader_thread, args=[proc, label.set_text])
t.daemon = True # exit with the program
t.start()

完整代码示例。