xtd::iformatable Class Reference

Inheritance diagram for xtd::iformatable:

Definition

Provides functionality to format the value of an object into a string representation.

Namespace

xtd

Library

xtd.core

Remarks

The xtd::iformattable interface converts an object to its string representation based on a format string and a locale.

A format string typically defines the general appearance of an object. For example, the xtd framework supports the following:

* Standard format strings for formatting enumeration values (see [Enumeration Format Strings]()).

* Standard and custom format strings for formatting numeric values (see [Standard Numeric Format Strings]() and [Custom Numeric Format Strings]()).

* Standard and custom format strings for formatting date and time values (see [Standard Date and Time Format Strings]() and [Custom Date and Time Format Strings]()).

* Standard and custom format strings for formatting time intervals (see [Standard time_span Format Strings]() and [Custom TimeSpan Format Strings]()).

You can also define your own format strings to support formatting of your application-defined types.

The xtd::iformattable interface defines a single method, xtd::iformatable::to_string, that supplies formatting services for the implementing type. The xtd::iformatable::to_string method can be called directly. In addition, it is called automatically by the xtd::convert.to_string methods, and by methods that use the composite formatting feature in the xtd framework. Such methods include xtd::console::write_line, xtd::string::format, and xtd::text::string_builder::apend_format, among others. The ToString method is called for each format item in the method's format string.

The xtd::iformattable interface is implemented by the base data types.

Notes to Implementers

Classes that require more control over the formatting of strings than xtd::iformattable::to_string() provides should implement xtd::iformattable. A class that implements xtd::iformattable must support the "G" (general) format specifier. Besides the "G" specifier, the class can define the list of format specifiers that it supports. In addition, the class must be prepared to handle a format specifier that is null. For more information about formatting and formatting codes, see [Formatting Type]()s

Examples

The following example shows how to use xtd::iformatable interface.

#include <xtd/console>
#include <xtd/environment>
#include <xtd/iformatable>
 
using namespace xtd;
 
class foo : public object, public iformatable {
public:
  explicit foo(int value) : value_ {value} {}
  
  using object::to_string;
  string to_string(const string& format, const std::locale& loc) const override {return string::format(string::format("{{:{}}}", format), value_);}
  
private:
  int value_ = 0;
};
 
auto main() -> int {
  auto f = foo {42};  
  console::out << "standard output :" << environment::new_line;
  console::out << "  " << f << environment::new_line;
  console::out << "  " << f.to_string() << environment::new_line;
  console::out << string::format("  {}", f) << environment::new_line;
  console::out << string::format("  0b{:b8}", f) << environment::new_line;
  console::out << "  0b" << f.to_string("b8", std::locale {}) << environment::new_line;
  console::write_line();
 
  console::write_line("write_line :");
  console::write("  ");
  console::write_line(f);
  console::write("  ");
  console::write_line(f.to_string());
  console::write_line("  {}", f);
  console::write_line("  0b{:b8}", f);
  console::write("  0b");
  console::write_line(f.to_string("b8", std::locale {}));
}
 
// This code produces the following output :
//
// standard output :
//   42
//   42
//   42
//   0b00101010
//   0b00101010
//
// write_line :
//   42
//   42
//   42
//   0b00101010
//   0b00101010

Examples

format_class_with_specified_formating.cpp, iformatable.cpp, iformatable_vs_to_string.cpp, and sprintf_class_with_specified_formating.cpp.

Public Methods
virtual xtd::string	to_string (const xtd::string &format, const std::locale &loc) const =0
	Formats the value of the current instance using the specified format.

Member Function Documentation

to_string()

virtual xtd::string xtd::iformatable::to_string ( const xtd::string &  format, const std::locale &  loc  ) const

pure virtual

Formats the value of the current instance using the specified format.

Parameters

format	The format to use -or- A xtd::string::empty_string ("") to use the default format defined for the type of the xtd::iformattable implementation.
loc	An std::locale object that contains locale information (see std::locale).

Returns

The value of the current instance in the specified format.

Implemented in xtd::date_time, xtd::guid, xtd::time_span, xtd::box< type_t >, and xtd::enum_object< enum_t >.

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The documentation for this class was generated from the following file:

• xtd.core/include/xtd/iformatable.h