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| -rw-r--r-- | doc/manual_experimental.md | 27 |
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diff --git a/doc/manual_experimental.md b/doc/manual_experimental.md index 72e883cbc..dd28fa67c 100644 --- a/doc/manual_experimental.md +++ b/doc/manual_experimental.md @@ -2382,6 +2382,33 @@ In the example above `CppClass` has a deleted default constructor. Notice how by Notice when calling a constructor in the section of a global variable initialization, it will be called before `NimMain` meaning Nim is not fully initialized. +Constructor Initializer +======================= + +By default Nim initializes `importcpp` types with `{}`. This can be problematic when importing +types with a deleted default constructor. In order to avoid this, one can specify default values for a constructor by specifying default values for the proc params in the `constructor` proc. + +For example: + +```nim + +{.emit: """/*TYPESECTION*/ +struct CppStruct { + CppStruct(int x, char* y): x(x), y(y){} + int x; + char* y; +}; +""".} +type + CppStruct {.importcpp, inheritable.} = object + +proc makeCppStruct(a: cint = 5, b:cstring = "hello"): CppStruct {.importcpp: "CppStruct(@)", constructor.} + +(proc (s: CppStruct) = echo "hello")(makeCppStruct()) +# If one removes a default value from the constructor and passes it to the call explicitly, the C++ compiler will complain. + +``` + Member pragma ============= |