Minimal parse-time hook before BuildDocument() for read-only extraction

[DomCR]

Discussed in #1031

^{Originally posted by sreekanthedayar April 13, 2026}
We use ACadSharp for read-only extraction, not editing. We need a minimal hook at parse time, before BuildDocument(), so we can observe each object/template as it is read and emit our own output incrementally without retaining the full CadDocument. Would you be open to exposing that hook in the reader/builder path?

To implement this feature I think the hook should be located when the Templates are added to the DocumentBuilder and when the template is build (it will still have unreferenced properties until the whole document is read).

The information that will be send it could be a clone of the current state of the CadObject (this will increase the reading time depending on the object size if the hook is present), and for the references (handles in dwg and handles and names for dxf) that can be stored in a dictionary which it will link the type/property to the handle (maybe using the current dxf codes for the objects which they are already assigned to the properties).

@sreekanthedayar, please confirm the criteria for the feature.

[sreekanthedayar]

Sorry, i missed the notification. Yes, this is directionally what we need. The key part for us is a read-only hook during parse/build, especially when templates are added to DocumentBuilder and when they are built, so we can emit incremental output before BuildDocument() finishes.

We would prefer the hook payload to be as lightweight as possible, ideally a snapshot/DTO of the fields needed for streaming output rather than a full clone of the CadObject. A full clone could work, but it may add too much overhead for our high-concurrency use case.

For references, using handle-based tracking for DWG and handle/name tracking for DXF sounds good. That would let us preserve identity and resolve links on our side without retaining the full CadDocument. So yes, this is the right direction, as long as the hook remains read-only and lightweight enough for incremental extraction.