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