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When creating, copying or restoring lightweight objects always call __INIT. This is needed, because restore will not touch nosave variables, and __INIT might have side-effects that are needed. Also when copying and restoring free any previous contents of variables (might come from __INIT or the UID hook). And when pragma share_variables is in effect, abort __INIT also in lightweight objects.
76 lines
2.6 KiB
Text
76 lines
2.6 KiB
Text
CONCEPT
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lwobjects
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INTRODUCTION
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Lightweight objects are a cross between regular objects and structs.
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Like regular objects they are build from programs (.c files) and
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encapsulate data and functions. Like structs they are automatically
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destructed, they can be copied and saved.
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As with regular objects its variables are hidden from outside
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objects, its functions can be called with call_other() and related
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efuns.
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Lightweight objects are passed by reference.
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DEFINITION
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Lightweight objects are created from a program, i.e. an LPC file.
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This file needs to have the pragma
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#pragma lightweight
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to allow being used as a lightweight object. This pragma implies
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the no_clone pragma (which can be overridden with the clone pragma).
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There are no restriction on the program itself. It can inherit
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other programs. Those programs don't need to have that pragma,
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but the compiler might warn about unsuitable programs.
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USAGE
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A lightweight objects is created by calling the efun new_lwobject():
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lwobject lwo = new_lwobject("/obj/foo");
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The efun new_lwobject() will load the file to create a blueprint
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from it (which is a regular object) and then creates a lightweight
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object therefrom.
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The efun can be given optional arguments that are passed to the
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H_CREATE_LWOBJECT driver hook.
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Functions of the lightweight object can be called with the efuns
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call_other() and its companions and operators:
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lwo->fun();
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lwo.fun();
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MISCELLANEOUS
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Only declarative casts to lwobject are possible, there is no
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conversion of any other type to lwobjects available (therefore
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there is no to_lwobject() efun).
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Support for lightweight objects is signaled by the macro
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__LPC_LWOBJECTS__.
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Lightweight objects have a UID and EUID and therefore can also
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do file operations or create new objects themselves.
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Lightweight objects can be serialized with save_value(), so
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any outside program can inspect its variables. To really hide
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variable contents they must be nosave.
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Prior to restoring or copying a lightweight object all variables
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of the new lightweight object will be initialized regularly first
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when pragma init_variables is in effect.
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HISTORY
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Lightweight objects were introduced in LDMud 3.6.5.
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SEE ALSO
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structs(LPC), new_lwobject(E), call_other(E), configure_lwobject(E),
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lwobject_info(E)
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