Por que meu código do Menu de Mensagens não funciona quando dividido em funções?

Question

Abaixo estão dois programas python. Eles são exatamente iguais, exceto pelo fato de um ser dividido em duas funções. No entanto, apenas o que é dividido em duas funções não funciona - a segunda função não funciona. Por que isso seria?

Observe que o código foi retirado deste post útil do blog .

Sem funções (trabalhos):

import gtk

def show_window_function(x, y):
    print x
    print y

# get the indicate module, which does all the work
import indicate

# Create a server item
mm = indicate.indicate_server_ref_default()
# If someone clicks your server item in the MM, fire the server-display signal
mm.connect("server-display", show_window_function)
# Set the type of messages that your item uses. It's not at all clear which types
# you're allowed to use, here.
mm.set_type("message.im")
# You must specify a .desktop file: this is where the MM gets the name of your
# app from.
mm.set_desktop_file("/usr/share/applications/nautilus.desktop")
# Show the item in the MM.
mm.show()

# Create a source item
mm_source = indicate.Indicator()
# Again, it's not clear which subtypes you are allowed to use here.
mm_source.set_property("subtype", "im")
# "Sender" is the text that appears in the source item in the MM
mm_source.set_property("sender", "Unread")
# If someone clicks this source item in the MM, fire the user-display signal
mm_source.connect("user-display", show_window_function)
# Light up the messaging menu so that people know something has changed
mm_source.set_property("draw-attention", "true")
# Set the count of messages in this source.
mm_source.set_property("count", "15")
# If you prefer, you can set the time of the last message from this source,
# rather than the count. (You can't set both.) This means that instead of a
# message count, the MM will show "2m" or similar for the time since this
# message arrived.
# mm_source.set_property_time("time", time.time())
mm_source.show()

gtk.mainloop()

Com funções (a segunda função é executada mas não funciona de fato):

import gtk

def show_window_function(x, y):
    print x
    print y

# get the indicate module, which does all the work
import indicate

def function1():
    # Create a server item
    mm = indicate.indicate_server_ref_default()
    # If someone clicks your server item in the MM, fire the server-display signal
    mm.connect("server-display", show_window_function)
    # Set the type of messages that your item uses. It's not at all clear which types
    # you're allowed to use, here.
    mm.set_type("message.im")
    # You must specify a .desktop file: this is where the MM gets the name of your
    # app from.
    mm.set_desktop_file("/usr/share/applications/nautilus.desktop")
    # Show the item in the MM.
    mm.show()

def function2():
    # Create a source item
    mm_source = indicate.Indicator()
    # Again, it's not clear which subtypes you are allowed to use here.
    mm_source.set_property("subtype", "im")
    # "Sender" is the text that appears in the source item in the MM
    mm_source.set_property("sender", "Unread")
    # If someone clicks this source item in the MM, fire the user-display signal
    mm_source.connect("user-display", show_window_function)
    # Light up the messaging menu so that people know something has changed
    mm_source.set_property("draw-attention", "true")
    # Set the count of messages in this source.
    mm_source.set_property("count", "15")
    # If you prefer, you can set the time of the last message from this source,
    # rather than the count. (You can't set both.) This means that instead of a
    # message count, the MM will show "2m" or similar for the time since this
    # message arrived.
    # mm_source.set_property_time("time", time.time())
    mm_source.show()

function1()
function2()
gtk.mainloop()

    

Answer 1

mm_source é local para function2. Quando a função2 é concluída, ela sai do escopo e é coletada como lixo. Isso faz com que seja rapidamente adicionado e, em seguida, removido do menu antes que você possa vê-lo.

Para impedir que isso aconteça, basta retornar o objeto mm_source ao código de chamada e mantê-lo em uma variável. Você provavelmente vai querer fazer a mesma coisa com o seu mm também. Como segue:

import gtk

def show_window_function(x, y):
    print x
    print y

# get the indicate module, which does all the work
import indicate

def function1():
    # Create a server item
    mm = indicate.indicate_server_ref_default()
    # If someone clicks your server item in the MM, fire the server-display signal
    mm.connect("server-display", show_window_function)
    # Set the type of messages that your item uses. It's not at all clear which types
    # you're allowed to use, here.
    mm.set_type("message.im")
    # You must specify a .desktop file: this is where the MM gets the name of your
    # app from.
    mm.set_desktop_file("/usr/share/applications/nautilus.desktop")
    # Show the item in the MM.
    mm.show()
    return mm

def function2():
    # Create a source item
    mm_source = indicate.Indicator()
    # Again, it's not clear which subtypes you are allowed to use here.
    mm_source.set_property("subtype", "im")
    # "Sender" is the text that appears in the source item in the MM
    mm_source.set_property("sender", "Unread")
    # If someone clicks this source item in the MM, fire the user-display signal
    mm_source.connect("user-display", show_window_function)
    # Light up the messaging menu so that people know something has changed
    mm_source.set_property("draw-attention", "true")
    # Set the count of messages in this source.
    mm_source.set_property("count", "15")
    # If you prefer, you can set the time of the last message from this source,
    # rather than the count. (You can't set both.) This means that instead of a
    # message count, the MM will show "2m" or similar for the time since this
    # message arrived.
    # mm_source.set_property_time("time", time.time())
    mm_source.show()
    return mm_source

my_mm = function1()
my_mm_source = function2()
gtk.mainloop()