What?
We would like to create:
A header file
#pragma once // optional
#ifndef _INCLUDED_HEADER_HEADER_0_H
#define _INCLUDED_HEADER_HEADER_0_H
// optional extra line
#ifndef STD_STRING_INCLUDED
#define STD_STRING_INCLUDED
#include <string>
#endif
// includes (with optional header guard)
#ifndef _INCLUDED_HEADER_HEADER_1_H
#include "header_1.h"
#endif
#ifndef _INCLUDED_HEADER_HEADER_2_H
#include "header_2.h"
#endif
// ...
// content here...
A class declaration
// class (complexity = 3):
class header_0_Class
{
private:
int m_variable_0;
double m_variable_1;
float m_variable_2;
public:
header_0_Class()
: m_variable_0( 0 )
, m_variable_1( 0.0 )
, m_variable_2( 0.0f )
{ }
void setm_variable_0(int v) { m_variable_0 = v; }
int getm_variable_0() const { return m_variable_0; }
void setm_variable_1(double v) { m_variable_1 = v; }
double getm_variable_1() const { return m_variable_1; }
void setm_variable_2(float v) { m_variable_2 = v; }
float getm_variable_2() const { return m_variable_2; }
};
It is a simple class with N-different variables with getters and setters. This class declaration can be put in a header file.
A Cpp file
#ifndef _INCLUDED_HEADER_HEADER_0_H
#include "header_0.h"
#endif
#ifndef _INCLUDED_HEADER_HEADER_1_H
#include "header_1.h"
#endif
#ifndef _INCLUDED_HEADER_HEADER_2_H
#include "header_2.h"
#endif
int main()
{
header_0_Class object_header_0_Class;
header_1_Class object_header_1_Class;
header_2_Class object_header_2_Class;
return 0;
}
Source file where all of our classes are used - just by simple object creation.
Why?
We would like to have an option to test compile time of code structure. We have several options to test:
- various structure configuration: We can use the generator to create different code configurations. For instance, simple test could involve only one cpp file that include N header files. Each header file includes all other header files as well.
- #pragma once: How this improves the compilation time?
- additional include guard: How this improves the compilation time?
Structure
Generator - Main class that is runs the generation process. Created in
main in generator.cpp file.It has some important members:
- m_headerCount - number of headers to generate
- m_complexCount - how generated classes are complex, or simply how many fields they have.
SourceFile - Base class that describes source file to be generated and the creation method. Holds info like fileName, type (Header or Cpp), and a list of header files that are included - both .h files and .cpp files can include things.
HeaderFile - Can create a header file.
CppFile - Can create a cpp file.
ClassGenerator - Knows how to create declaration of a class.
main() - creates one Generator and initializes it with params obtained from command line.
Examples
generator.exe 3 3 path ifDef pragmaOnce
Generates 3 header files with 3 different classes that have 3 members inside. We use all headers options so both pragma and additional include guards will be used.
#pragma once
#ifndef _INCLUDED_HEADER_HEADER_0_H
#define _INCLUDED_HEADER_HEADER_0_H
#ifndef STD_STRING_INCLUDED
#define STD_STRING_INCLUDED
#include <string>
#endif
#ifndef _INCLUDED_HEADER_HEADER_1_H
#include "header_1.h"
#endif
#ifndef _INCLUDED_HEADER_HEADER_2_H
#include "header_2.h"
#endif
generator.exe 3 3 path
Same as above, but header file looks like that:
#ifndef _INCLUDED_HEADER_HEADER_0_H
#define _INCLUDED_HEADER_HEADER_0_H
#include <string>
#include "header_1.h"
#include "header_2.h"
Todo
- Classes like SourceFile, HeaderFile and CppFile violates SRP (they hold info about a file and at the same time they are used to generate such file). Maybe there should be some additional class like HeaderGenerator, CppGenerator or similar.
- Automatic makefile/project creation would be helpful as well
- Ability to use techniques like forward declarations (and use pointers/referances instead of values) to reduce compile time coupling. This would require better ClassGenerator implementation
- Probably the class HeaderFile should be extended to support system header files, like
<string>,<windows.h>etc...
Last words
Whole sources can be found on github: @fenbf/articles/inludeTest.
In the next blog post finally, I will be able to write about the results of my compilation tests using this code generator.