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69 lines
1.7 KiB
D
69 lines
1.7 KiB
D
/* Create classes from their modules and names.
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*
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* Copyright: Copyright (C) D Language Foundation 2023
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* License: $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
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* Authors: Walter Bright, Steven Schveighoffer
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* Source: $(DRUNTIMESRC core/_factory.d)
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*/
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module core.factory;
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/**
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* Create instance of class specified by the module symbol and a string
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* representing the name of the class.
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* The class must either have no constructors or have
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* a default constructor.
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* Params:
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* mod = symbol representing the module that the class is in
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* classname = string representing the name of the class
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* Returns:
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* null if failed
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* Example:
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* ---
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* module foo.bar;
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*
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* class C
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* {
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* this() { x = 10; }
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* int x;
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* }
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*
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* void main()
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* {
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* auto c = cast(C)factory!(foo.bar)("C");
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* assert(c !is null && c.x == 10);
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* }
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* ---
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*/
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Object factory(alias mod)(string classname)
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{
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foreach(cl; _getModuleClasses!mod)
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{
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if (cl.stringof == classname)
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return cl.classinfo.create();
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}
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return null;
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}
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@system unittest
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{
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Object valid_obj = factory!object("Object");
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Object invalid_obj = factory!object("__this_class_doesnt_exist__");
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assert(valid_obj !is null);
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assert(invalid_obj is null);
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}
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/**************************************
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* Retrieve as a tuple all the types of the top level classes in the module mod.
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*/
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private template _getModuleClasses(alias mod) {
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alias result = _AliasSeq!();
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static foreach(m; __traits(allMembers, mod))
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static if(is(__traits(getMember, mod, m) == class))
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result = _AliasSeq!(result, __traits(getMember, mod, m));
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alias _getModuleClasses = result;
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}
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private template _AliasSeq(TList...) { alias _AliasSeq = TList; }
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