How formatters operate

• TFormattable classes
• TFormatter classes

TFormattable provides a wrapper for data, allowing it to be formatted by a TFormatter. The system provides the following TFormattable derived classes to wrap a specific type of data:

• TFormattableNumber encapsulates a number, using the data type double, allowing it to be formatted by a class derived from TNumberFormatter.
• TFormattableText encapsulates a text string, an instance of TText, allowing it to be formatted by TSimpleTextFormatter.
• TFormattableTime encapsulates time data, an instance of TTime, allowing it to be formatted by a class derived from TDateTimeFormatter.
• TFormattableParameterList encapsulates an indexed list of TFormattable instances for use by a TParameterFormatter.

• Format takes formattable data and formats it as text data.
• Scan parses text data into the appropriate type of formattable data.

• TDateTimeFormatter is the abstract base class for classes that format and scan instances of TFormattableTime. See "Date and time formatting" on page 246 for information on TDateTimeFormatter subclasses.
• TNumberFormatter is the abstract base class for classes that format and scan instances of TFormattableNumber. See "Using TNumberFormatter subclasses" on page 238 for information on TNumberFormatter subclasses that format specific types of numbers.
• TSimpleTextFormatter formats and scans instances of TFormattableText.
• TParameterFormatter takes a list of TFormattable data parameters (an instance of TFormattableParameterList) and formats them into text strings, or scans text into a list of data parameters. This class also takes a text template, which you use to create strings with variable segments.
• TChoiceFormatter specifies a mapping between numerical values and a set of text strings or TParameterFormatter instances. Use this class to provide a set of conditional formatters.