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+# Code Style Guide for dal.cpp
+
+## Formatting (enforced by `.clang-format`)
+
+- Base style: LLVM
+- Indent: 4 spaces (no tabs)
+- Column limit: 150
+- Brace style: Attach (opening `{` on same line)
+- Pointer binding: to type (`T*` not `T *`)
+- Short `if`/loops: not on single line
+- Short functions: allowed on single line
+- Namespace indent: all
+- Standard: C++17
+
+## Naming Conventions
+
+| Element              | Convention                    | Examples                                          |
+|----------------------|-------------------------------|---------------------------------------------------|
+| Classes/Structs      | PascalCase + trailing `_`     | `Date_`, `Vector_<>`, `ThreadPool_`, `Model_<T_>` |
+| Template params      | Single letter + `_`           | `T_`, `E_`, `LHS_`, `RHS_`, `OP_`                |
+| Functions/Methods    | PascalCase                    | `FromExcel()`, `AddDays()`, `GeneratePath()`      |
+| Member variables     | Trailing `_`                  | `serial_`, `spot_`, `vol_`, `name_`               |
+| Local variables      | snake_case                    | `num_paths`, `batch_size`, `n_threads`            |
+| Constants/Macros     | UPPER_SNAKE_CASE              | `BATCH_SIZE`, `EPSILON`, `FORCE_INLINE`           |
+| Files                | lowercase, no separators      | `threadpool.cpp`, `blackscholes.hpp`              |
+| Test files           | `test_` prefix, snake_case    | `test_vectors.cpp`, `test_date.cpp`               |
+| Namespaces           | PascalCase or lowercase       | `Dal`, `Dal::AAD`, `namespace exception`          |
+
+## Header Files
+
+- Always `#pragma once` (no include guards)
+- File header comment: `// Created by <author> on <date>.`
+- Include order: standard library -> dal headers -> local headers
+- Platform header: most `.cpp` files include `<dal/platform/platform.hpp>`
+
+## Namespace Patterns
+
+- Top-level: `namespace Dal { ... }`
+- Nested for modules: `Dal::AAD`, `Dal::Script`, `Dal::Date`, `Dal::String`
+- Anonymous `namespace { }` for file-local helpers
+- Public API flattens everything into `Dal::` via `using` aliases
+
+## Type Idioms
+
+- `using` over `typedef`: `using base_t = std::vector<E_>;`
+- `Handle_<T_>`: wraps `std::shared_ptr<const T_>` for const-correct shared ownership
+- `std::unique_ptr<T_>`: for exclusive ownership and `Clone()` return types
+- `Vector_<E_>`: private inheritance from `std::vector<E_>` with custom API
+- `String_`: case-insensitive string via custom `ci_traits`
+- `explicit` constructors on all single-argument constructors
+- `[[nodiscard]]` + `const` on all pure getters
+
+## Error Handling
+
+- Custom `Exception_` (from `std::runtime_error`) capturing file/line/function
+- Macro-based: `THROW(msg)`, `ASSERT(cond, msg)` (debug-only), `REQUIRE(cond, msg)` (configurable)
+- Stack context via `NOTICE(x)` / `NOTE(msg)` macros
+- Safe pointer ops: `ASSIGN(p, v)`, `DEREFERENCE(p, v)`
+
+## Common Patterns
+
+- **CRTP**: AAD expression templates
+- **Visitor**: Script AST traversal (`Visitor_<V_>`, `Visitable_<...>`)
+- **Factory**: `NewLinear()`, `NewSobol()`, `Clone()`
+- **Singleton**: `ThreadPool_::instance_`, thread-local `Tape()`
+- **RAII**: Smart pointers, scope-based tape/stack cleanup
+- **Private inheritance**: `Vector_<E_> : private std::vector<E_>`
+
+## Key Macros
+
+- `FORCE_INLINE`: platform-specific forced inline
+- `BASE_EXPORT`: DLL export for shared builds
+- `RUN_AT_LOAD(code)`: execute at program startup
+- `BAREWORD(w)`: generate `static const String_`
+- `RETURN_STATIC(...)`: return static local variable
+- `DYN_PTR(n, t, s)`: `dynamic_cast` shorthand
+
+## Test Conventions (Google Test)
+
+- Always simple `TEST(Suite, Name)` — no fixtures (`TEST_F`)
+- Strongly prefer `ASSERT_*` over `EXPECT_*`
+- Float comparison: `ASSERT_NEAR(actual, expected, tol)` with `1e-8` to `1e-10`
+- Scoped blocks `{ }` within a single `TEST` for sub-cases
+- Test suites: PascalCase (`AADTest`, `VectorTest`)
+- Test names: PascalCase with `Test` prefix (`TestNumberAdd`)
+
+## Comment Style
+
+- Sparse — code is self-documenting
+- Focus on "why" not "what"
+- Single-line `//` for inline notes
+- No docstrings or doxygen-style comments
+- File headers are the only mandatory comments