Doyxgen onetime macro expansion / expansion command - macros

Question

I have some code like the following example:
/** #file HelloPi.c */
/** The definition of pi */
#define PI 3.1415
/** #brief The main function.
* #details Prints the value of #PI, which is actual defined as 3.1415. */
void main()
{
printf("The value of pi is %f\n",PI);
}
In my doxygen dokumentation I would like to to have NO macro expansion for PI (and other defines) in general.
But on one paragraph in the documentation I need the value of pi (e.g. #details description of the main function).
Is there any possibility to expand the macro at this single part of documentation with a command or something? Something like /** #details ...the value of #PI is $(PI).*/
I only know the build-in MACRO_EXPANSION tag which works for the whole documentation: https://www.doxygen.nl/manual/preprocessing.html :-/
Thanks for help :)
Jan
Edit:
Add an other example which maybe better describes my Problem:
/** #file ErrorHandling.c */
#define ERR_CODE_POWERUNIT 1001 ///< Error in power unit */
/** #page errors
* [value of ERR_CODE_POWERUNIT ] means \copybrief ERR_CODE_POWERUNIT */
void errHandler(int error)
{
if(error=ERR_CODE_POWERUNIT)
printf("Error %d occur\n",ERR_CODE_POWERUNIT);
}
In the documentation I would like to have:
"1001 means Error in power unit"

Answer 1

In doxygen there is no possibility to do a conversion of a predefined variable (only) in the documentation.
You used in your documentation the an environment variable $(PI) but ths is quite cumbersome as you have to st the environment variable each time.
A better solution would be to use an ALIASES like:
ALIASES += pi=3.1415
or
ALIASES +\= "The value of PI = 3.14159265359..."
with which you define a command \pi that can be used in the documentation and will be replaced with the text / commands in the alias.
/** #details ...the value of #PI is \pi.*/
would result in something like (by head:
...the value of #PI is 3.1415