On Monday, 27 March 2023 at 22:22:26 UTC, Jeremy wrote:
Is there a way I can define a manifest constant from the
compiler command-line, like the -Dmacro option for C compilers?
You can do this way:
```
dmd -version=FEATURE_A
```
```D
import std.stdio;
void main()
{
version(FEATURE_A)
{
writeln("feature A enabled");
}
}
```
Unfortunatly there is not #ifndef, so in case you want to make
sure FEATURE_A is not there you'll have to do:
```D
import std.stdio;
void main()
{
version(FEATURE_A)
{}
else
{
writeln("feature A not available");
}
}
```
or
```D
import std.stdio;
version(FEATURE_A)
{
enum FEATURE_A_AVAILABLE = true;
}
else
{
enum FEATURE_A_AVAILABLE = false;
}
void main()
{
static if (!FEATURE_A_AVAILABLE)
{
writeln("feature A not available");
}
}
```
For some reason they force us to be overly verbose
Or it's possible to do it, but i don't know much more than this
about ``-version``
(if you use ldc compiler, it's ``-d-version=``)
