Simplify DelimWriter factory functions

Author: vincentlaucsb

AGENTS.md

@@ -70,6 +70,7 @@ See `tests/AGENTS.md` for test strategy, checklist, and conventions.
    - **Trivial one-liner accessors** may be unconditionally `inline` in the header when the call overhead is measurable and the body will never change.
    - **Consolidation:** If a `.cpp` would be under ~100 lines *and* the split causes excessive comment duplication between the two files, prefer a single `.hpp` with definitions marked `inline` (free functions and methods alike). Do not use `CSV_INLINE` for consolidated definitions — `CSV_INLINE` expands to empty in multi-header mode, which would produce ODR violations across TUs. Do not consolidate just for brevity — only when duplication is the dominant cost.
 7. **Prefer LF (`\n`) line endings for tracked source, test, CMake, and Markdown files.** When you touch a file with mixed line endings, normalize the edited file to LF unless there is a file-specific reason not to. Avoid introducing mixed CRLF/LF endings in the same file.
+8. **Keep preprocessor directives flush left.** `#define`, `#if`, `#ifdef`, `#else`, and `#endif` should start at column 0. Code inside multi-line macros should be indented exactly as the equivalent non-macro code would be; do not add extra indentation just because it lives inside a macro body.
 
 ### Rules for Comments
 1. **Always update or remove incorrect comments.**

ARCHITECTURE.md

@@ -22,6 +22,7 @@ Notes:
 - When editing a function, remove `@param` and `@return` descriptions that merely restate the function name or signature.
 - Private member naming should prefer trailing underscores; when editing mixed-style code, normalize the touched region toward that convention.
 - Prefer LF (`\n`) line endings for tracked source, test, CMake, and Markdown files; when touching a file with mixed endings, normalize it to LF unless there is a file-specific reason not to.
+- Keep preprocessor directives flush left; `#define`, `#if`, `#ifdef`, `#else`, and `#endif` should start at column 0, and code inside multi-line macros should be indented as if the macro wrapper were not present.
 - Compatibility macros defined in `common.hpp` must only be referenced after including `common.hpp`. See AGENTS.md and CLAUDE.md for details.
 - API constraints should be user-friendly: do not over-constrain templates unless needed for correctness, safety, or a measured performance win.
 - `CSVReader` is intentionally non-copyable and move-enabled; use explicit ownership transfer patterns (`std::move`, `std::unique_ptr`) at API boundaries.

CLAUDE.md

@@ -39,6 +39,7 @@
 - **`CSVReader` is non-copyable and move-enabled** — prefer explicit ownership transfer (`std::move`) or `std::unique_ptr<CSVReader>` when handing off parser ownership
 - **Prefer trailing underscore for private members** — when touching mixed-style code, normalize the edited region toward names like `source_` and `leftover_`
 - **Prefer LF (`\n`) line endings** for tracked source, test, CMake, and Markdown files — when touching a file with mixed endings, normalize it to LF unless a file-specific reason says otherwise
+- **Keep preprocessor directives flush left** — `#define`, `#if`, `#ifdef`, `#else`, and `#endif` start at column 0; indent code inside multi-line macros exactly as equivalent non-macro code would be
 - **Prefer user-friendly API constraints** — do not narrow template constraints unless required for correctness, safety, or a measured performance win; if common containers/ranges already work, keep them accepted
 - **Respect compile-time compatibility macros** — keep constructs like `IF_CONSTEXPR` and `CONSTEXPR_VALUE` unless there is a correctness bug
 - **Do not rewrite compile-time logic to silence warnings** — prefer tightly scoped suppression at the exact site when needed

README.md

@@ -660,6 +660,7 @@ auto writer = make_csv_writer(ss);
 // auto writer = make_tsv_writer(ss);               // For tab-separated files
 // DelimWriter<stringstream, '|', '"'> writer(ss);  // Your own custom format
 // set_decimal_places(2);                           // How many places after the decimal will be written for floats
+// writer.set_auto_flush(false);                    // Buffer writes until flush()/destructor
 
 writer << vector<string>({ "A", "B", "C" })
     << deque<string>({ "I'm", "too", "tired" })

docs/source/csv_writing.md

@@ -14,6 +14,14 @@ CSV/TSV data.
 Use `csv::make_csv_writer()` for comma-delimited output and
 `csv::make_tsv_writer()` for tab-delimited output.
 
+If you want buffered behavior, call `set_auto_flush(false)` on the writer
+instead of using a separate factory:
+
+@code
+std::stringstream output;
+auto writer = csv::make_csv_writer(output).set_auto_flush(false);
+@endcode
+
 ## Writing Containers with `operator<<`
 
 Any row-like container of string-convertible values can be streamed directly.