| Zesstra | 5481d49 | 2021-04-08 20:07:06 +0200 | [diff] [blame] | 1 | CONCEPT |
| 2 | lwobjects |
| 3 | |
| 4 | INTRODUCTION |
| 5 | Lightweight objects are a cross between regular objects and structs. |
| 6 | Like regular objects they are build from programs (.c files) and |
| 7 | encapsulate data und functions. Like structs they are automatically |
| 8 | destructed, they can be copied and saved. |
| 9 | |
| 10 | As with regular objects its variables are hidden from outside |
| 11 | objects, its functions can be called with call_other() and related |
| 12 | efuns. |
| 13 | |
| 14 | Lightweight objects are passed by reference. |
| 15 | |
| 16 | |
| 17 | DEFINITION |
| 18 | Lightweight objects are created from a program, i.e. an LPC file. |
| 19 | This file needs to have the pragma |
| 20 | |
| 21 | #pragma lightweight |
| 22 | |
| 23 | to allow being used as a lightweight object. This pragma implies |
| 24 | the no_clone pragma (which can be overridden with the clone pragma). |
| 25 | |
| 26 | There are no restriction on the program itself. It can inherit |
| 27 | other programs. Those programs don't need to have that pragma, |
| 28 | but the compiler might warn about unsuitable programs. |
| 29 | |
| 30 | |
| 31 | USAGE |
| 32 | A lightweight objects is created by calling the efun new_lwobject(): |
| 33 | |
| 34 | lwobject lwo = new_lwobject("/obj/foo"); |
| 35 | |
| 36 | The efun new_lwobject() will load the file to create a blueprint |
| 37 | from it (which is a regular object) and then creates a lightweight |
| 38 | object therefrom. |
| 39 | |
| 40 | The efun can be given optional arguments that are passed to the |
| 41 | H_CREATE_LWOBJECT driver hook. |
| 42 | |
| 43 | Functions of the lightweight object can be called with the efuns |
| 44 | call_other() and its companions and operators: |
| 45 | |
| 46 | lwo->fun(); |
| 47 | lwo.fun(); |
| 48 | |
| 49 | |
| 50 | MISCELLANEOUS |
| 51 | Only declarative casts to lwobject are possible, there is no |
| 52 | conversion of any other type to lwobjects available (therefore |
| 53 | there is no to_lwobject() efun). |
| 54 | |
| 55 | Support for lightweight objects is signaled by the macro |
| 56 | __LPC_LWOBJECTS__. |
| 57 | |
| 58 | Lightweight objects have a UID and EUID and therefore can also |
| 59 | do file operations or create new objects themselves. |
| 60 | |
| 61 | Lightweight objects can be serialized with save_value(), so |
| 62 | any outside program can inspect its variables. To really hide |
| 63 | variable contents they must be nosave. |
| 64 | |
| 65 | |
| 66 | HISTORY |
| 67 | Lightweight objects were introduced in LDMud 3.6.5. |
| 68 | |
| 69 | |
| 70 | SEE ALSO |
| 71 | structs(LPC), new_lwobject(E), call_other(E), configure_lwobject(E), |
| 72 | lwobject_info(E) |