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+# Compile Time Execution Problems (Metaprogramming)
+2016-11-02
+
+## Memory and Types
+
+Compile time execution (CTE) is a stage of the compiler which runs any Odin code the
+user requests before the creation of the executable. The data modified and generated
+by this stage will be used as the initialization data for the _compiled_ code.
+
+The CTE stage is an interpreter running the generated _single static assignment_ (SSA)
+tree for the requested code. When using the memory generated by the interpreter for the
+compiled code, there are a few problems. The main problem being: pointers will point
+to invalid memory addresses. This is becaused the memory space of the interpreter is
+completely different to the memory space of the executable (compiled code).
+
+The table below presents which data types are safe for transferal and which are not.
+
+Key:
+
+* Y - Yes
+* N - No
+* D - Dependent on elements
+* ? - Highly depends on a lot of factors (most likely no)
+
+| Type      | Safe?                                                                  |
+|-----------|------------------------------------------------------------------------|
+| boolean   | Y                                                                      |
+| integer   | Y                                                                      |
+| float     | Y                                                                      |
+| pointer   | N - Maybe safe if never changed                                        |
+| string    | Y - Even though (ptr+int) interally, still safe to convert to constant |
+| any       | N - (ptr+ptr)                                                          |
+| array     | D                                                                      |
+| vector    | Y - Elements can only be boolean, integer, or float (thus safe)        |
+| slice     | N - Internally (ptr+int+int)                                           |
+| maybe     | D                                                                      |
+| struct    | D                                                                      |
+| enum      | Y                                                                      |
+| union     | N - (blob+int)                                                         |
+| raw_union | N - ^^^                                                                |
+| tuple     | D                                                                      |
+| proc      | ? - Need to solve the next problem                                     |
+
+
+## Calling procedures (external and internal)
+
+If all the procedures are only from within the code itself, i.e. not a loaded pointer,
+then it is "safe". However, calling external procedures and passing procedures from the
+interpreter to external programs _will_ cause problems as many of the procedures are not
+stored in _real_ memory. This causes numerous problems.
+
+**TODO:**
+
+* Look at how other languages solve this problem (e.g. LUA)
+* ???