bdlar_symbolicconverter

Detailed Description

Provide a utility for convert types with matching member symbols.

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Basic Usage

Purpose

Provide a utility for convert types with matching member symbols.

Classes

• bdlar::SymbolicConverter: symbolic converter utility

See also

bdlat_symbolicconverter

Description

The bdlar::SymbolicConverter utility provided by this component defines a single parameterized function convert. The convert function takes two arguments: a destination and a source object. The destination and source objects may be of different types. Details about the used conversion rules can be found in the bdlat_symbolicconverter component description.

Both bdlat_SymbolicConverter and bdlar::SymbolicConverter classes implement absolutely equivalent functionality and produce the same results. The difference in not what they do, but how they do it. While bdlat_SymbolicConverter uses template metaprogramming and generates a lot of template instances, bdlar::SymbolicConverter doesn't generate any code at compile time - all the required code is pre-compiled. It can reduce code bloat, compile time, and the load on the compiler in general, which can be benificial for large data schemas.

Usage

This section illustrates intended use of this component.

Example 1: Basic Usage

This component can be used with types supported by the bdlat framework. In particular, types generated by the bas_codegen.pl tool can be used. For example, suppose we have the following XML schema inside a file called xsdfile.xsd:

<?xml version='1.0' encoding='UTF-8'?>
<xs:schema xmlns:xs='http://www.w3.org/2001/XMLSchema'
           xmlns:bdem='http://bloomberg.com/schemas/bdem'
           elementFormDefault='unqualified'>
 
    <xs:complexType name='Employee'>
        <xs:sequence>
            <xs:element name='Name'   type='string'/>
            <xs:element name='Dept'   type='string'/>
            <xs:element name='Age'    type='int'/>
            <xs:element name='Salary' type='float'/>
        </xs:sequence>
    </xs:complexType>
 
    <xs:complexType name='Trainee'>
        <xs:sequence>
            <xs:element name='Name' type='string'/>
            <xs:element name='Dept' type='string'/>
            <xs:element name='Age'  type='int'/>
        </xs:sequence>
    </xs:complexType>
 
</xs:schema>

Using the bas_codegen.pl tool, we can generate C++ classes for this schema:

$ bas_codegen.pl -g h -g cpp -p test xsdfile.xsd

This tool will generate the header and implementation files for the test_employee and test_trainee components in the current directory.

Now suppose we want to create a hireTrainee function, that converts a trainee to an employee. Such a function could be written as follows:

#include <test_employee.h>
#include <test_trainee.h>
 
#include <bdlar_symbolicconverter.h>
 
using namespace BloombergLP;
 
int hireTrainee(test::Employee       *result,
                const test::Trainee&  trainee,
                float                 salary)
{
    int retCode = bdlar::SymbolicConverter::convert(result, trainee);
 
    result->salary() = salary;
 
    return retCode;
}

The hireTrainee function can be used as follows:

void usageExample()
{
    test::Trainee trainee;
 
    trainee.name() = "Bob";
    trainee.dept() = "RnD";
    trainee.age()  = 24;
 
    test::Employee employee;
 
    int result = hireTrainee(&employee, trainee, 20000.00f);
 
    assert(0         == result);
    assert("Bob"     == employee.name());
    assert("RnD"     == employee.dept());
    assert(24        == employee.age());
    assert(20000.00f == employee.salary());
}