massProps
A mass-properties rollup spends a year on documentation and follows its sibling's API
Comparison · Infra & APIs
rollupTree vs watcher
A side-by-side editorial comparison of rollupTree and watcher — release velocity, themes, recent moves, and the top alternatives to consider.
rollupTree vs watcher: at a glance
What is rollupTree?
The recursive-computation engine under massProps grows the accessors its consumer needed
rollupTree performs recursive computations over tree and DAG structures — the generic engine that its author's massProps package uses to roll mass properties up an assembly breakdown. It is small and moves slowly: five releases in a year, of which two are README and vignette work. The current surface added row-level get and set accessors by key and by id at 0.4.0.
What is watcher?
watcher is a thin filesystem-events binding whose releases are mostly build work.
The package wraps libfswatch in an R6 Watcher class for monitoring files and directories. Seven releases over sixteen months have added a vector path argument and two accessor methods, and spent the rest of their effort on build portability — non-standard system library locations, Windows bi-arch source builds on old rtools, and most recently removing the cmake requirement so the bundled source compiles with the R toolchain alone.
rollupTree vs watcher: editorial side-by-side
rollupTree
0.0INFRA · APIS
The recursive-computation engine under massProps grows the accessors its consumer needed
◆ Current state
rollupTree performs recursive computations over tree and DAG structures — the generic engine that its author's massProps package uses to roll mass properties up an assembly breakdown. It is small and moves slowly: five releases in a year, of which two are README and vignette work. The current surface added row-level get and set accessors by key and by id at 0.4.0.
◆ Where it's heading
The package develops in response to its one visible consumer. The 0.4.0 accessors appeared in January 2026 and massProps switched to them thirteen days later; 0.4.1 then fixed missing column names in the setters, which is the kind of defect only real use surfaces. Before that, 0.3.0's default_validate_dag() extended validation past strict trees to directed acyclic graphs, widening what structures the engine will accept.
◆ Prediction
On the established pattern the next release will be whatever massProps needs next, discovered by using it. A DAG validator suggests non-tree structures are in scope, but nothing in these notes says that path is being pushed further.
watcher
0.0INFRA · APIS
watcher is a thin filesystem-events binding whose releases are mostly build work.
◆ Current state
The package wraps libfswatch in an R6 Watcher class for monitoring files and directories. Seven releases over sixteen months have added a vector path argument and two accessor methods, and spent the rest of their effort on build portability — non-standard system library locations, Windows bi-arch source builds on old rtools, and most recently removing the cmake requirement so the bundled source compiles with the R toolchain alone.
◆ Where it's heading
The API is deliberately small and appears finished; the work that remains is making the C dependency install cleanly everywhere. Dropping cmake follows the same move nanonext made, which is not a coincidence — both come from the same author and both are aiming at environments where installing a build system is not an option.
◆ Prediction
With cmake gone and the bundled library current, further releases are most likely to track libfswatch upstream rather than extend the R interface.
Alternatives to rollupTree and watcher
Other Infra & APIs products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either rollupTree or watcher.
writeAlizer
Six months of releases and not one of them touched the scoring models
samplr
A cognitive-science sampling package ships once, then goes quiet for eighteen months
stochvol
A Bayesian volatility sampler in its maintenance decade, paying for its own speed
midr
A black-box interpreter reaches CRAN, then learns multi-class and survival responses
GeoThinneR
Spatial thinning grows a result object, and the API breaks to make room for it
See all rollupTree alternatives → · See all watcher alternatives →
Recent activity from rollupTree and watcher
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 1mo agowatchercmake dropped from the bundled library build
- 3mo agowatcherBundled libfswatch updated to 1.20.1
- 6mo agorollupTreeMissing column names in the new row setters
- 6mo agorollupTreeRow-level get and set accessors by key and by id
- 8mo agowatcherWindows CPU usage fix for sub-second latency
- 1y agowatcherSystem libfswatch found in non-standard locations
- 1y agorollupTreeMinor vignette improvements
- 1y agorollupTreeBadges and GitHub Actions added to the README
- 1y agowatcherMultiple paths per watcher, and older Windows builds fixed
- 1y agorollupTreedefault_validate_dag() extends validation past strict trees
- 1y agowatcherAccessor methods replace public Watcher fields
Frequently asked questions
What is the difference between rollupTree and watcher?
They serve adjacent needs but don't currently overlap on shipped themes. rollupTree and watcher are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is rollupTree better than watcher?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. rollupTree and watcher are shipping at a similar cadence (velocity 0.0 vs 0.0, both within Sparkpulse's "active" band). For your specific use case, the alternatives sections above list other Infra & APIs products to evaluate alongside.
What are the best alternatives to rollupTree?
Top rollupTree alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "rollupTree alternatives" section above for the current picks, or visit /alternatives/rolluptree for the full list with editorial commentary on each.
What are the best alternatives to watcher?
Top watcher alternatives in Infra & APIs are ranked by recent ship velocity. Browse the "watcher alternatives" section above for the current picks, or visit /alternatives/watcher for the full list with editorial commentary on each.