Christmas Holiday: by W. Somerset Maugham.

One cannot help remembering a short story by Maugham where the father sends the boy to a holiday to see Paris and arms the young man with explicit instructions about how to be safe by clinging to virtue; the boy however does gamble and win tremendously, goes back with a young woman whom he sees steal his money and when she sleeps takes it from her hiding place - only to discover that he came away with her money as well; and tells his father that he did all right in spite of breaking every rule of his father's virtuous code of conduct. The story is told by the father to the protagonist / writer with a worry about the boy going on believing his father was wrong and virtues and code of conduct means nothing, and the father is worried about the boy's future. The writer / protagonist cannot help laughing.

The similarity of this theme makes one wonder if the writer did not think of both the versions at the same time and elaborate on the story with serious twist for a novel while keeping the wry wit that was his forte for the short stories where it belonged.