Wrapper Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 25.6 垃圾回收安全 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 25.7 Non-constant Data through a Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 25.14线程安全 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271 25.15关于 14不要过度使用宏 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353 37.15不要把不安全的操作暴露在接口层 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353 37.16不要重载基础容器类型的方法 . . .

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values

ERROR: UndefRefError: access to undefined reference This avoids the need to continually check for null values. However, not all object fields are references. Julia considers some types to be "plain data" raw pointer value must be called at runtime for precompilation to work (Ptr objects will turn into null pointers unless they are hidden inside an isbits object). This includes the return values of the the missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 21.1 Propagation of Missing Values