- 1 current stop: learning
- 2 upcoming
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Finish after stop 5
Stop 1 of 5 · Bookshop warehouse: new shelf plan
Trick to keep in mind+3 XP
Adding optional is free; renaming, reshaping or newly requiring costs a new version.
A change is breaking if some existing client that worked yesterday could fail today. Clients that ignore unknown fields shrug off an extra optional field. Renaming or reshaping a field, or demanding a parameter that used to be optional, can break callers that did nothing wrong. Only those need a new version.
Read it once, then a question tests whether the trick stuck.