Add ability to update slack messages

[TheJokersThief]

What

• Add a method to update messages
• Alter send_message method so that if the message timestamps are present, it will update the message(s) instead

Why

Updating messages is really handy, to communicate status, follow up with feedback, or replace some placeholder text while the bot works on an answer.

Example usage

Here's a basic example of sending an initial message, doing some processing (in this case sleeping) and then updating the original message to avoid clutter in a channel.

@botcmd
def hello(self, msg, args):
    """Say hello to someone"""
    first_msg = self._bot.send_message(
        Message(
            to=msg.frm,
            body="Give me a moment while I get that for you!",
        )
    )

    time.sleep(10)

    first_msg.body = "Ah, here we go. The answer is 42"

    updated_msg = self._bot.update_message(first_msg)

Misc

Related to :

• Revisit: Add a way to update existing message #35
• Add support for editing messages in slack. #37
• Add update message functionality to Slack backend errbot#1269

[sijis]

Thanks for the contribution.

Would you be able to include some code example on usage of new method within the description of PR?

[TheJokersThief]

Yes, of course!

Here's a basic example of sending an initial message, doing some processing (in this case sleeping) and then updating the original message to avoid clutter in a channel.

@botcmd
def hello(self, msg, args):
    """Say hello to someone"""
    first_msg = self._bot.send_message(
        Message(
            to=msg.frm,
            body="Give me a moment while I get that for you!",
        )
    )

    time.sleep(10)

    first_msg.body = "Ah, here we go. The answer is 42"

    updated_msg = self._bot.update_message(first_msg)

[nzlosh]

This looks good to me and thank you again for the contribution.