Overview

Rather than provide a complex inheritable family of classes with super-imposed mixins to represent the varying degrees of generic device functionalities (e.g. source, sink, seekable...) a rather more simpler (and faster) concept based method is used for the devices in ecl's input-output library. The concepts are required to validate the classes for use by higher level structures such as streams.

Compiling & Linking

Include the following at the top of any translation unit for which you are running compile time checks on your blueprint classes.

#include <ecl/concepts.hpp>
 
using ecl::InputCharDeviceConcept;
using ecl::OutputCharDeviceConcept;
using ecl::InputOutputCharDeviceConcept;
using ecl::InputByteDeviceConcept;
using ecl::OutputByteDeviceConcept;
using ecl::InputOutputByteDeviceConcept;

Since it only uses macros and templatised objects, no linking is required for just this feature.

Concept Definition

InputCharDevice

An input device class has to satisfy the following conditions:

long read(char &c) : read a single character from the device buffer.
long read(char *s, unsigned long n) : read a char buffer from the device buffer.

OutputCharDevice

An output device class has to satisfy the following conditions:

long write(char &c) : write a single character from the device buffer.
long write(char *s, unsigned long n) : write a char buffer from the device buffer.
void flush() : a method for flushing the output device buffer to the device.

InputOutputCharDevice

An input-output device class has to satisfy the conditions required by both input and output devices simultaneously.

ByteDevice

The three byte device concepts are similar except they add additional read/write capabilities for the other is_byte types (refer to ecl_mpl's type traits). Namely char, signed char and unsigned char.

Usage

Generally, you won't need to use these directly. Rather they're embedded in other ecl objects such as streams. However, a simple example of a device function definition and the concept check usage is outlined below.

#include <ecl/concepts/devices.hpp>
 
using ecl::InputCharDevice;
 
template <typename Device>
class MyStream {
public:
    
    MyStream(Device *device) {
        compile_time_concept_check(InputCharDeviceConcept<Device>);
    }
};