• 七月的泛型

    七月的泛型

    1. struct Repo⟨T⟩ {
    2.     db DB
    3. }
    5. fn new_repo⟨T⟩(db DB) Repo⟨T⟩ {
    6.     return Repo⟨T⟩{db: db}
    7. }
    9. // This is a generic function. V will generate it for every type it's used with. 
    10. fn (r Repo⟨T⟩) find_by_id(id int) ?T {  
    11.     table_name := T.name // in this example getting the name of the type gives us the table name 
    12.     return r.db.query_one⟨T⟩('select * from $table_name where id = ?', id)
    13. }
    15. db := new_db()
    16. users_repo := new_repo⟨User⟩(db)
    17. posts_repo := new_repo⟨Post⟩(db)
    18. user := users_repo.find_by_id(1)? 
    19. post := posts_repo.find_by_id(1)?

    为了方便阅读，允许使用⟨⟩代替<>。vfmt最终会将⟨⟩替换为<>。