泛型(Generics)

struct Repo⟨T⟩ {
    db DB
}

fn new_repo⟨T⟩(db DB) Repo⟨T⟩ {
    return Repo⟨T⟩{db: db}
}

// This is a generic function. V will generate it for every type it's used with. 
fn (r Repo⟨T⟩) find_by_id(id int) ?T {  
    table_name := T.name // in this example getting the name of the type gives us the table name 
    return r.db.query_one⟨T⟩('select * from $table_name where id = ?', id)
}

db := new_db()
users_repo := new_repo⟨User⟩(db)
posts_repo := new_repo⟨Post⟩(db)
user := users_repo.find_by_id(1)? 
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<>。

The initial version of V had generics because arrays and maps were built with them. Later I figured out a way to implement these data structures without generics. This simplified code greatly.

Since I no longer needed them, they were moved to a branch, because maintaining generics is tough. Generics will not be available when the language is released in June, but they should be back by July.

摘录自V语言作者Alex