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    <p>To create a dynamic array dynamically, you need a reference to its type info structure (<code>PTypeInfo</code>) to pass to <code>DynArraySetLength</code>; calling <code>DynArraySetLength</code> and passing a reference to a nil pointer is how you can create a new dynamic array. If the specific shape of dynamic array does not already exist in your Delphi program, there will be no specific <code>PTypeInfo</code> pointer that the compiler will generate for you. In this case, you would have to generate the corresponding <code>PTypeInfo</code> data structure yourself. This is possible, though tedious.</p> <p>Frankly, I'd recommend you use a different structure than built-in Delphi dynamic arrays to represent arrays in your scripting language-like problem. In the long run it will probably be a lot less work than trying to dynamically generate the low-level RTTI data, which is more likely to change from version to version now that it has a much higher level abstraction in the Rtti unit.</p>
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    1. COI really hope the format of TTypeInfo and TTypeData doesn't change, except to add new branches to the TTypeData union tree that fill in gaps in the existing RTTI. I've been doing a lot of theoretical work in the area of dynamic class and type generation in order to implement a scripting system that integrates seamlessly with compiled Delphi code through RTTI. I'm a week or two away from having a working POC compiler now, and it would be rather annoying to have to completely rework my type data generation code when a new version comes out.
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      1. USMason Wheeler
    2. CO@Mason It's less a case of completely changing, than having more data appended on the end. It's a real PITA to jam in extra data without breaking code. As it is, the RTTI format contributes a fairly substantial size penalty largely because its encoding can't be optimized much. It would be nice to consider something like e.g. .NET metadata tables, which use a conciser representation. Instead, Delphi RTTI is left with every xref taking up a minimum of 4 bytes, and frequently with redundant strings for names that could be pooled. But that can't happen within the current framework.
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    3. COFair enough. It's a real mess trying to write code to read RTTI structures because of all of the inline data arrays without a static size, meaning the compiler can't find the field that comes next and you need a bunch of pointer math. If your new format could get rid of *that* I'd be all for it, and I'd only need to rewrite my generation code once. The part that bugged me was when you said "from version to version," implying that there will (might) be format revamps with each new release, or a significant fraction of them. That would be a pain.
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