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Runtime String

libxr_string.hpp provides LibXR::RuntimeStringView<Source, Args...>, a runtime-built, retained NUL-terminated string for module names, topic names and runtime-formatted results that are built once or rewritten repeatedly.

  • The text is kept in internal storage and can be read repeatedly through View() / CStr().
  • A formatted instance allocates capacity from a compile-time upper bound before its first rewrite and reuses that storage.

Two construction paths​

  1. Plain text copy / concatenation
LibXR::RuntimeStringView<> topic_name("camera/front");
LibXR::RuntimeStringView<> path("/dev/", "ttyUSB0");

This path accepts text inputs only; numbers go through the rewrite path below. Character pointers must reference valid NUL-terminated strings.

  1. Formatted rewrite
LibXR::RuntimeStringView<"camera_{}", unsigned int> name;
if (name.Reformat(7U) != LibXR::ErrorCode::OK) {
  // handle the failure
}
// name.View() == "camera_7"

LibXR::RuntimeStringView<"frame_%03u", unsigned int> frame;
if (frame.Reprintf(5U) != LibXR::ErrorCode::OK) {
  // handle the failure
}
// frame.View() == "frame_005"
  • Reformat(...) uses brace-style formatting.
  • Reprintf(...) uses printf-style formatting.
  • The argument types of a rewrite call must match Args... exactly.

Semantics​

  • Formatted arguments must be value types with a statically bounded size; runtime string arguments are rejected at compile time, and text concatenation uses the plain RuntimeStringView<> constructors.
  • The destructor does not free the allocated storage; the type suits names and formatted results allocated once and reused.
  • Status() reports the latest construction or rewrite result; after a failure the visible text is empty.
  • Copy construction and all assignments are deleted; move construction takes over the storage and leaves the source empty.

Common access APIs​

  • std::string_view View() const
  • const char* CStr() const
  • size_t Size() const
  • bool Empty() const
  • ErrorCode Status() const
  • Implicit conversion to std::string_view and const char*.