"The art of simplicity is a puzzle of
        complexity” Doug Horton
      
      Feel free to skip this section. It is here to document the process and the
      decisions made during design to be able to review and to reevaluate and to
      ensure the relevancy and the correctness of those decisions and ultimately
      the design. Still, this section might be useful for understanding why and how
      certain decisions have been made and why Boost.Convert
      is the way it is.
    
        Boost.Convert has been designed to satisfy the following
        user requirements:
      
- 
            (R1) Boost.Convert shall provide
            a mechanism and an interface that take a value of type TypeIn
            and yield a value of type TypeOut using an algorithm
            of type Converter;
          
- 
            (R2) Boost.Convert shall provide
            a mechanism and an interface to indicate success or failure of the requested
            conversion;
          
- 
            (R3) Boost.Convert shall provide
            fully-functional interfaces for two different program flows where
            
- 
                  (R3a) error-processing is orthogonal to the
                  normal program flow (exception-throwing interface);
                
- 
                  (R3b) normal and error-processing flows are
                  part of the same program flow (non-throwing interface);
                
 
- 
            (R4) The throwing interface shall return the result
            of successful conversion or shall throw an exception;
          
- 
            (R5) The non-throwing interface shall return the
            result and/or some indication of conversion success or failure;
            
- 
                  (R5a) there shall be means to distinguish
                  success from failure;
                
- 
                  (R5b) the result of conversion shall only
                  be available when conversion succeeds;
                
- 
                  (R5c) when conversion fails, an optional fallback
                  value shall be returned instead if supplied;
                
- 
                  (R5d) in the case of failure (with no fallback
                  provided) an attempt to retrieve the result shall result in an
                  exception thrown;
                
 
- 
            (R6) Boost.Convert shall provide
            a uniform interface suitable for generic programming;
          
- 
            (R7) Boost.Convert shall not
            interfere with or intercept any exceptions that are not part of the official
            converter interface (i.e. exceptions caused by malfunction, etc.);
          
- 
            (R8) Converters shall be independent of and shall
            not rely on the Boost.Convert infrastructure.