The phrase "hanging a raincoat in front of the door" can also be used to mean thinking ahead and preparing for what will happen. For example, if a person wants to take an exam, he should make preparations in advance before the exam, such as reviewing the contents of the exam and previewing possible problems. These preparations are like hanging a raincoat in front of the door so that you can use it whenever you need it.
"Hanging a raincoat in front of the door" can also be used to describe making preparations in advance in daily life to avoid losses due to excessive trust in others. For example, if someone needs to recruit an employee, a series of screening and background checks can be conducted before the recruitment to try to avoid choosing the wrong person. Doing so is like hanging a raincoat in front of the door, which can avoid being cheated or hurt by other risks when necessary.