Add error-code constructors for directory (#143)

Add `directory::directory(std::error_code&)` and
`directory::directory(std::string_view, std::error_code&)`

include/tmp/directory

@@ -39,11 +39,20 @@ namespace tmp {
 class TMP_EXPORT directory : public entry {
 public:
   /// Creates a unique temporary directory
-  /// @param label     A label to attach to the temporary directory path
+  /// @param[in] label A label to attach to the temporary directory path
   /// @throws std::filesystem::filesystem_error if cannot create a directory
   /// @throws std::invalid_argument             if the label is ill-formatted
   explicit directory(std::string_view label = "");
 
+  /// Creates a unique temporary directory
+  /// @param[out] ec Parameter for error reporting
+  explicit directory(std::error_code& ec);
+
+  /// Creates a unique temporary directory
+  /// @param[in]  label A label to attach to the temporary directory path
+  /// @param[out] ec    Parameter for error reporting
+  explicit directory(std::string_view label, std::error_code& ec);
+
   /// Creates a unique temporary copy recursively from the given path
   /// @param path      A path to make a temporary copy from
   /// @param label     A label to attach to the temporary directory path

src/directory.cpp

@@ -19,6 +19,12 @@ constexpr fs::copy_options copy_options =
 directory::directory(std::string_view label)
     : entry(create_directory(label)) {}
 
+directory::directory(std::error_code& ec)
+    : entry(create_directory("", ec)) {}
+
+directory::directory(std::string_view label, std::error_code& ec)
+    : entry(create_directory(label, ec)) {}
+
 directory directory::copy(const fs::path& path, std::string_view label) {
   directory tmpdir = directory(label);