format_context::get is now move only

example/batch_inserts.cpp

@@ -123,7 +123,7 @@ static std::string compose_batch_insert(
     // Formatting can fail (e.g. if you supply strings with invalid UTF-8),
     // so get() returns a boost::system::result<std::string>.
     // Calling value() will retrieve the string or throw an exception on failure.
-    return ctx.get().value();
+    return std::move(ctx).get().value();
 }
 
 void main_impl(int argc, char** argv)

example/dynamic_filters.cpp

@@ -163,7 +163,7 @@ std::string compose_get_employees_query(const boost::mysql::any_connection& conn
         ctx.append_value(boost::mysql::identifier(*filts.order_by));
     }
 
-    return ctx.get().value();
+    return std::move(ctx).get().value();
 }
 
 void main_impl(int argc, char** argv)

example/snippets.cpp

@@ -1579,7 +1579,7 @@ std::string compose_update_query(
     ctx.append_value(employee_id);
 
     // Retrieve the generated query string
-    return ctx.get().value();
+    return std::move(ctx).get().value();
 }
 //]
 #endif
@@ -1842,7 +1842,7 @@ void section_sql_formatting(string_view server_hostname, string_view username, s
         boost::mysql::basic_format_context<std::pmr::string> ctx(conn.format_opts().value());
 
         // Compose your query as usual
-        std::pmr::string query = ctx.get().value();
+        std::pmr::string query = std::move(ctx).get().value();
         //]
     }
 #endif

include/boost/mysql/format_sql.hpp

@@ -250,7 +250,15 @@ class format_context_base
     error_code error_state() const noexcept { return impl_.ec; }
 };
 
-/// (EXPERIMENTAL) Implements stream-like SQL formatting (TODO).
+/**
+ * \brief (EXPERIMENTAL) Implements stream-like SQL formatting.
+ * - Concrete classes for SQL stream formatting
+ * - Owns an OutputString, to which characters will be appended when formatting.
+ *   Should satisfy the OutputString concept.
+ * - See format_context for the most common type alias.
+ * - Move only
+ * - Create, append, then call get.
+ */
 template <BOOST_MYSQL_OUTPUT_STRING OutputString>
 class basic_format_context : public format_context_base
 {
@@ -288,8 +296,7 @@ class basic_format_context : public format_context_base
         assign(rhs);
     }
 
-    // TODO: do we make this move-only?
-    system::result<OutputString> get()
+    system::result<OutputString> get() &&
     {
         auto ec = error_state();
         if (ec)
@@ -334,7 +341,7 @@ std::string format_sql(constant_string_view format_str, const format_options& op
 {
     format_context ctx(opts);
     format_sql_to(format_str, ctx, args...);
-    return detail::check_format_result(ctx.get());
+    return detail::check_format_result(std::move(ctx).get());
 }
 
 }  // namespace mysql

include/boost/mysql/impl/internal/sansio/set_character_set.hpp

@@ -42,7 +42,7 @@ class set_character_set_algo : public sansio_algorithm, asio::coroutine
         // For security, if the character set has non-ascii characters in it name, reject it.
         format_context ctx(format_options{ascii_charset, true});
         ctx.append_raw("SET NAMES ").append_value(charset.name);
-        return ctx.get();
+        return std::move(ctx).get();
     }
 
 public:

test/unit/test/format_sql.cpp

@@ -499,7 +499,7 @@ error_code format_single_error(const Arg& arg)
 {
     format_context ctx(opts);
     ctx.append_value(arg);
-    return ctx.get().error();
+    return std::move(ctx).get().error();
 }
 
 BOOST_AUTO_TEST_CASE(individual_error)
@@ -752,7 +752,7 @@ BOOST_AUTO_TEST_CASE(format_strings_invalid_arguments)
 BOOST_AUTO_TEST_CASE(format_context_success)
 {
     // Helper
-    auto get = [](format_context_base& ctx) { return static_cast<format_context&>(ctx).get().value(); };
+    auto get = [](format_context_base& ctx) { return static_cast<format_context&&>(ctx).get().value(); };
 
     // Empty
     BOOST_TEST(format_context(opts).get().value() == "");
@@ -804,7 +804,7 @@ BOOST_AUTO_TEST_CASE(format_context_charset)
         .append_value("abd\xff{}")
         .append_raw(" + ")
         .append_value(identifier("i`d`ent\xff`ifier"));
-    BOOST_TEST(ctx.get().value() == "SELECT '\xff{abc' + 'abd\xff{}' + `i``d``ent\xff`ifier`");
+    BOOST_TEST(std::move(ctx).get().value() == "SELECT '\xff{abc' + 'abd\xff{}' + `i``d``ent\xff`ifier`");
 }
 
 BOOST_AUTO_TEST_CASE(format_context_backslashes)
@@ -816,13 +816,13 @@ BOOST_AUTO_TEST_CASE(format_context_backslashes)
         .append_value("ab'cd\"ef")
         .append_raw(" + ")
         .append_value(identifier("identif`ier"));
-    BOOST_TEST(ctx.get().value() == "SELECT 'ab''cd\"ef' + `identif``ier`");
+    BOOST_TEST(std::move(ctx).get().value() == "SELECT 'ab''cd\"ef' + `identif``ier`");
 }
 
 BOOST_AUTO_TEST_CASE(format_context_error)
 {
     // Helper
-    auto get = [](format_context_base& ctx) { return static_cast<format_context&>(ctx).get().error(); };
+    auto get = [](format_context_base& ctx) { return static_cast<format_context&&>(ctx).get().error(); };
 
     // Just an error
     BOOST_TEST(get(format_context(opts).append_value("bad\xff")) == client_errc::invalid_encoding);