C Memory Representation

text/0001-c-memory-representation.md

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+Summary
+=======
+
+We need to figure out rules for how we map types from C++ to C. There's several considerations that need to be made such as public/private attributes in a class or struct and std library types. The easiest solution would be to have everything go on the heap and have all the types in C forward declare the C++ classes, but that is not going to be the best in terms of performance.
+
+So, there's some rules that we can follow to handle public, private, and standard library types.
+
+Solution
+========
+
+We follow the following set of rules:
+
+- If a type contains a std library type, then it has to on the heap.
+- If a type does not contain a std library type, but it contains private fields, then it has to be represented in c as an unsigned char array.
+- If the type does not contain a std library type, and it only contains public fields, then it can be implementented as a struct in C.
+
+Examples
+========
+
+Heap
+----
+
+### C++
+
+```cpp
+class MyType {
+    std::string my_value;
+}
+```
+
+### C
+
+```c
+struct MyType;
+```
+
+Private
+-------
+
+### C++
+
+```cpp
+class MyType {
+private:
+    int my_value;
+}
+```
+
+### C
+
+```c
+typedef unsigned char MyType[2];
+```
+
+
+Public
+------
+
+### C++
+
+```cpp
+class MyType {
+public:
+    int my_value;
+}
+```
+
+### C
+
+```c
+typedef struct {
+    int my_value;
+}
+```