antistrefo / rules
Cursor rule4 starsChanged 9 days agoMITView on GitHub
Reuse utils instead of hand-rolled buffers, strings, and hashes
We split this reuse.mdc into the rules it gives an agent
1 rule. About 0 are common, 0 are distinctive, and 1 is very specific to this project.
≈0
Common · estimate
Many files like this have a rule of this kind.
≈0
Distinctive · estimate
This author's own choices. Worth a look.
1
Very specific
Tied to their project's names, files or tools. Probably skip.
- Common
- Distinctive
- Very specific
- Very specific: line 8
Before writing a function, read docs/util-catalog.md and grep src/utils/.
≈ “Common” is an estimate: at least 1 in 5 of the 6,350 Cursor rule files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Files
---
description: Reuse utils instead of hand-rolled buffers, strings, and hashes
alwaysApply: true
---
# Reuse first
Before writing a function, read `docs/util-catalog.md` and grep `src/utils/`. Do not reinvent what exists.
| If you were about to write | Use |
|---|---|
| a byte-by-byte copy loop | `re_memcpy` on a sized span |
| `realloc` or manual buffer doubling | `re_strbuf_*` |
| a grow-array with capacity doubling | `re_vec_*` |
| `strlen` / `strcmp` / `strcat` / `strtok` | `re_str_*` |
| hex nibble arithmetic | `re_hex_*` |
| `sprintf` or manual int-to-decimal | `re_strbuf_appendf`, `re_fmt_*` |
| `while (x) { x &= x - 1; }` | `re_bits_*` |
| a hand-rolled hash or CRC | `re_crc_*`, `re_hash_*` |
| splitting on `/` or `\` | `re_path_*` |
| a `switch` that emits `{"k":` | `re_jw_*` |
| `fprintf(stderr, ...)` | `re_log_*` |
Escape hatch: used once, 15 lines or fewer, and no loop over bytes stays `static` in the caller. Needed twice, or it loops over bytes, or it crosses a module: make a util first. Never inline a would-be util into its consumer. A util that would pass 500 lines splits; it is never absorbed.
Where files are headingNew Cursor rule files have more rules about planning and tracking tasks, and fewer about code style.
Of the Cursor rule files we read, the 3,978 first seen in the last six months, against the older ones: the kind of rule that gained most share, and the kind that lost most. About files like this in general, not this one, and an estimate, since a kind is a pattern in the words.
In this repository9 other files it gives its agents.
- .cursor/rules/architecture.mdcCursor rule
- .cursor/rules/banner.mdcCursor rule
- .cursor/rules/build.mdcCursor rule
- .cursor/rules/gate.mdcCursor rule
- .cursor/rules/layout.mdcCursor rule
- .cursor/rules/no-personal-emails.mdcCursor rule
- .cursor/rules/output.mdcCursor rule
- .cursor/rules/project.mdcCursor rule
- .cursor/rules/scope.mdcCursor rule
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