日志：简化日志记录

日志 简化日志记录。 var err error var l = log . V ( 0 ) // nil errors get ignored l . Err ( err ) // non nil errors are printed err = errors . New ( "we log non nil errors" ) l . Err ( err ) // or just write a string l . Str ( "hello" ) // and format it sometimes l . Strf ( "hello %s" , "world" )