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2acb5743fa
The documentation is now generated from markdown. Samples are generated from the tutorial pages. Testing is done by a Python script which runs the tests for a large number of compilers. This version is not very developer-friendly - the Python scripts need ways of limiting what compilers they try to run. If you don't have 15 compilers installed, you won't be able to run the tests in this commit. Fix coming soon.
1.4 KiB
1.4 KiB
Compile-time usage
When used with $cxx11, Better Enums are generated entirely during compilation.
All the data is available for use by your own constexpr functions. The
examples in this tutorial aren't very useful, but read the following tutorials
to get an idea of what can be done. Here, you will see the basics.
#include <iostream>
#ifndef BETTER_ENUMS_CONSTEXPR_TO_STRING
#define BETTER_ENUMS_CONSTEXPR_TO_STRING
#endif
<em>#include <enum.h></em>
<em>ENUM(Channel, int, Red = 1, Green = 2, Blue = 3)</em>
<em>constexpr</em> Channel channel = Channel::Green;
<em>constexpr</em> int value = <em>channel._to_integral()</em>;
<em>constexpr</em> const char *name = <em>channel._to_string()</em>;
<em>constexpr</em> Channel parsed = <em>Channel::_from_string("Red")</em>;
All of the above are computed during compilation. You can do apparently useless things such as:
<em>constexpr size_t length</em>(<em>const char *s</em>, <em>size_t index = 0</em>)
{
return <em>s[index] == '\0'</em> ? <em>index</em> : <em>length(s, index + 1)</em>;
}
<em>constexpr</em> size_t <em>length_of_name_of_second_constant</em> =
<em>length(Channel::_names()[1])</em>;
int main()
{
std::cout << <em>length_of_name_of_second_constant</em> << std::endl;
return 0;
}
Which prints "5", the length of "Green". That 5 was also computed during compilation.