fable: Perfect-forward arguments to fmt::format

Author: cassava

fable/include/fable/conf.hpp

@@ -321,8 +321,8 @@ class Conf {
   std::string resolve_file(const std::string& filename) const;
 
   template <typename... Args>
-  [[noreturn]] void throw_error(const char* msg, const Args&... args) const {
-    throw_error(fmt::format(msg, args...));
+  [[noreturn]] void throw_error(std::string_view format, Args&&... args) const {
+    throw_error(fmt::format(format, std::forward<Args>(args)...));
   }
   [[noreturn]] void throw_error(const std::string& msg) const;
   [[noreturn]] void throw_unexpected(const std::string& key, const std::string& msg = "") const;

fable/include/fable/error.hpp

@@ -41,7 +41,8 @@ class Error : public std::exception {
   explicit Error(const char* what) : err_(what) {}
 
   template <typename... Args>
-  explicit Error(const char* format, const Args&... args) : err_(fmt::format(format, args...)) {}
+  explicit Error(std::string_view format, Args&&... args)
+      : err_(fmt::format(format, std::forward<Args>(args)...)) {}
 
   virtual ~Error() noexcept = default;
 
@@ -59,9 +60,10 @@ class ConfError : public Error {
 
   ConfError(const Conf& c, const std::string& msg) : Error(msg), data_(c) {}
   ConfError(const Conf& c, const char* msg) : Error(msg), data_(c) {}
+
   template <typename... Args>
-  ConfError(const Conf& c, const char* format, const Args&... args)
-      : Error(format, args...), data_(c) {}
+  ConfError(const Conf& c, std::string_view format, Args&&... args)
+      : Error(format, std::forward<Args>(args)...), data_(c) {}
 
   std::string file() const { return data_.file(); }
   std::string root() const { return data_.root(); }
@@ -122,19 +124,49 @@ class SchemaError : public ConfError {
  public:  // Constructors
   virtual ~SchemaError() noexcept = default;
 
+  /**
+   * Construct SchemaError with a ConfError.
+   *
+   * \param c ConfError
+   * \param s Schema used for validation
+   */
   SchemaError(const ConfError& c, const Json& s) : ConfError(c), schema_(s) {}
 
+  /**
+   * Construct SchemaError with a ConfError.
+   *
+   * \param c ConfError
+   * \param s Schema used for validation
+   * \param ctx Extra contextual data as JSON
+   */
   SchemaError(const ConfError& c, const Json& s, const Json& ctx)
       : ConfError(c), schema_(s), context_(ctx) {}
 
+  /**
+   * Construct SchemaError.
+   *
+   * \param c Input Conf where error occurred
+   * \param s Schema used for validation
+   * \param format Message format string for fmt::format
+   * \param args Arguments to message format
+   */
   template <typename... Args>
-  SchemaError(const Conf& c, const Json& s, const char* format, const Args&... args)
-      : ConfError(c, format, args...), schema_(s) {}
-
+  SchemaError(const Conf& c, const Json& s, std::string_view format, Args&&... args)
+      : ConfError(c, format, std::forward<Args>(args)...), schema_(s) {}
+
+  /**
+   * Construct SchemaError.
+   *
+   * \param c Input Conf where error occurred
+   * \param s Schema used for validation
+   * \param ctx Extra contextual data as JSON
+   * \param format Message format string for fmt::format
+   * \param args Arguments to message format
+   */
   template <typename... Args>
-  SchemaError(const Conf& c, const Json& s, const Json& ctx, const char* format,
-              const Args&... args)
-      : ConfError(c, format, args...), schema_(s), context_(ctx) {}
+  SchemaError(const Conf& c, const Json& s, const Json& ctx, std::string_view format,
+              Args&&... args)
+      : ConfError(c, format, std::forward<Args>(args)...), schema_(s), context_(ctx) {}
 
  public:  // Special
   const Json& schema() const { return schema_; }