Announce: scripting fossil with tcl (early stages)
(1) By Stephan Beal (stephan) on 2025-05-24 16:24:28 [source]
For those who are Tcl-inclined...
As of today, libfossil has some rudimentary Tcl scripting capabilities, provided in the form of a Tcl loadable extension.
It's demonstrated in this test script and what features are available are documented here.
Current capabilities:
- Create new fossil context objects and use them to...
- Open/close repos.
- Resolve symbolic fossil names to their UUIDs or RIDs.
- Run arbitrary SQL, including access to the libfossil SQL functions, via a pretty spiffy pair of SQL-execution APIs:
- It has flexible way to specify data types when binding SQL parameters (keeping in mind that in Tcl, everything is a string).
- It can "eval" a user-provided script for each result row.
- Its query API can return query results directly to the caller.
- The user can specify one of several formats for data returned from a query, e.g. just column 3 of the first row, or column 2 of all rows, or one of several list-based and dict-based formats.
This code is all new - it was started only a week ago - and the list of TODOs is effectively endless, but it shows some promise. Collaborators are welcomed - get in touch.
(2) By Torsten Berg (torstenberg) on 2025-05-26 12:25:37 in reply to 1 [link] [source]
Wow. Cool to hear this.
This is another heavy argument for me to try libfossil! I have to find some time for this and explore the possibilities.
Thanks so much for doing all this!
(3) By Stephan Beal (stephan) on 2025-05-26 15:57:00 in reply to 2 [link] [source]
Thanks so much for doing all this!
Thank you for the feedback! This is my 9th(10th?) time binding sqlite to a scripting engine, so it's moving pretty quickly, but this is my first time using the C Tcl API for anything beyond literally "Hello, World!" so there's a learning curve there. Even so, the db part of the API is "mostly" feature-complete, with parameter binding and column fetching in multiple flavors, transactions, and scalar UDFs (aggregates and window functions are coming Real Soon Now™. The infrastructure is all in place, they just need to be added on top of it).
(4) By Torsten Berg (torstenberg) on 2025-05-27 18:37:49 in reply to 3 [link] [source]
If you need help with the Tcl C API, I can recommend to ask on comp.lang.tcl where you always will find some Tcl wizards listening. I have only limited experience with the C API (only having used it for some gdal binding to Tcl yet). In general, the Tcl C API function are quite well documented in the respective manual pages and there are good books on their basic usage.