Punctuate What Is Really There...

I have been on "hiatus" for a while. Actually I have been swamped for a while!! So I am back -- still swamped but back.

There is a question on FB about the word "but" and whether it should have a comma before it when it ends the sentence. Remember that we punctuate what is really there. This sentence just does not work with the comma because you do not know what is coming.

...I have always come to his rescue, but -- :-(

...I have always come to his rescue but not today.
...I have always come to his rescue, but this is just not reasonable.

(And these examples are putting aside the issue of whether he was interrupted or trailed off.)

Happy punctuating!