Each of us had a situation, where we had to invoke a few, same commands each time. Making it once is not that problematic, but when we are supposed to repeat given operations, it may be better just to create one function that will handle it all.
Sometimes we want to store some piece of information while using a terminal, for example, a result of an executed command. We usually save it into some temporary file which is going to be deleted after all. There’s a better way.
The macro mechanism in Elixir is not only an interesting metaprogramming feature - in fact, it is at the language's very core. And the more awesome fact is that, using macros, you can override the algorithm of defining functions itself!
So you don’t know what’s the type of struct you’re passing somewhere? Maybe it can be one of few types and you have to distinguish them? Or any other reason… But it’s about checking the struct type. Just use one of the coolest Elixir features - pattern matching!