arc/borrow.hpp

Static-lifetime loans, one-writer edit packs, and loan-pack alias checks with core-owner access gates.

Fit

• Use it when firmware structure, task lifetime, ownership, command parsing, or policy state needs a visible contract.
• Do not start here when a hardware-specific module already owns the same decision more directly.
• Verification focus: put the owner near board topology, make rollback explicit, and keep slow side effects on Core 0.

Arc Contract

• Header: arc/borrow.hpp
• Module group: Program Shape And Ownership
• CMake feature: core
• Closest example: .

Declare arc_requires(main_requires core) in the component that includes this header.

CMake And Include

include(${CMAKE_CURRENT_LIST_DIR}/../cmake/arc-deps.cmake)

arc_requires(main_requires core)

idf_component_register(
    SRCS "app_main.cpp"
    REQUIRES ${main_requires}
)

#include "arc/borrow.hpp"

Source Landmarks

Source landmarks: BorrowMode, StaticRef, StaticLoan, StaticRead, StaticMut, StaticReads, StaticWrites, StaticEdit, LoanPack, HasLoan, HasStaticRead, HasStaticWrite, HasStaticRefRead, HasStaticRefWrite, StaticReadable, StaticWritable, LoanReadable, LoanWritable, set, with_read, with_reads, with_write, with_edit.

Start From Zero

• Start from the closest example or the root project listed below.
• Load the ESP-IDF environment with . ./env.sh.
• Add the include and CMake feature only in the component that owns this lane.
• Keep board topology, buffers, and ownership in one visible owner type.
• Move from build proof to hardware proof only after the wiring or runtime dependency is known.

Owner Skeleton

namespace app {
void boot()
{
    // Put board policy, buffer ownership, and failure handling here.
    // Keep Core 1 hot work separate from Core 0 service work.
}
}

extern "C" void app_main()
{
    app::boot();
}

Step-By-Step Check

1. Decide whether this module owns silicon, memory, protocol bytes, or policy only.
2. Name the owner type once, close to the board topology.
3. Allocate any DMA or shared buffers before the hardware starts.
4. Initialize with the recoverable path while bringing up the board.
5. Switch to the fail-fast path only after the topology is treated as fixed.
6. Log from Core 0 after the hot path has handed off a compact event or snapshot.

Build Or Example

The root project is the smallest place to try this module.

. ./env.sh
idf.py build
idf.py -p /dev/ttyACM0 flash monitor

Runtime Check

The build command proves the dependency path. Runtime proof still needs the actual board condition that matches this module: attached device, loopback, radio peer, flash partition, sleep wake source, or captured serial/network output. Do not turn the example command into a performance or hardware claim without that evidence.

Next Reading

• Module Guide
• API Reference
• Examples