Compile-time functions
V provides several compile-time functions.
$tmpl
$tmpl is a compile-time function that allows you to embed a template into your code.
See Templates for more information.
$env
V can bring in values at compile time from environment variables.
$env('ENV_VAR') can also be used in top-level #flag and #include statements:
#flag linux -I $env('JAVA_HOME')/include.
module main
fn main() {
compile_time_env := $env('ENV_VAR')
println(compile_time_env)
}
$compile_error and $compile_warn
These two compile time functions are very useful for displaying custom errors/warnings during compile time.
Both receive as their only argument a string literal that contains the message to display:
example.v:
$if linux {
$compile_error('Linux is not supported')
}
fn main() {
}
Output:
example.v:4:5: error: Linux is not supported
2 |
3 | $if linux {
4 | $compile_error('Linux is not supported')
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5 | }
6 |