4.7 sdds::Page construction and field access

• name:
  sdds::Page, field access and assignment
• description:
  Represent one complete or projected SDDS page. A page shares an immutable layout and stores values using sdds::Scalar, sdds::Values, and sdds::ArrayData. A manually constructed page may begin with all fields loaded or unloaded.
• synopsis:
  explicit sdds::Page(std::shared_ptr<const sdds::Layout> layout,  
                      sdds::LoadMode load = sdds::LoadMode::All);  
  std::int64_t number() const noexcept;  
  std::int64_t rowCount() const noexcept;  
  bool recovered() const noexcept;  
  const sdds::Layout &layout() const;  
  bool parameterLoaded(index-or-name) const;  
  bool arrayLoaded(index-or-name) const;  
  bool columnLoaded(index-or-name) const;  
  bool allFieldsLoaded() const noexcept;  
  const sdds::Scalar &parameter(index-or-name) const;  
  const sdds::ArrayData &array(index-or-name) const;  
  const sdds::Values &column(index-or-name) const;  
  void setParameter(index-or-name, sdds::Scalar value);  
  void setArray(index-or-name, sdds::ArrayData value);  
  void setColumn(index-or-name, sdds::Values value);

  Here index-or-name denotes the overload accepting either std::size_t or std::string_view.

• arguments:
  • layout — Shared layout that governs the page.
  • load — Initial loaded-field state for a new page.
  • index-or-name — Field index or exact name.
  • value — Replacement value whose type must match the definition.
• return value:
  Status and access methods return page metadata, load state, or a const reference to stored data. Assignment methods have no return value and mark their fields loaded.
• exceptions:
  sdds::StateError for an unloaded or absent field, sdds::TypeError for a type mismatch, or sdds::FormatError for invalid array dimensions or inconsistent column lengths.
• see also:
  Sections 4.8, 4.10, and 4.19.