Custom Compiler Options
V provides the ability to set custom compiler options that can be used in program code. With their help, you can, for example, execute code only if the option was passed during compilation. V will be able to optimize such code, and will not include it in the binary if the option was not passed.
To pass a custom option, use the -d flag followed by the option name:
v -d verbose_debug_output .
To pass multiple options, use -d multiple times:
v -d verbose_debug_output -d another_flag .
Now in code, we can use compile-time if to check if a option was passed.
fn busniness_logic() {
$if verbose_debug_output ? {
println('some verbose debug output')
}
// ...
}
Notice the question mark after the option name in the
$ifexpression.
You can also use negation:
fn busniness_logic() {
$if !verbose_debug_output ? {
println('verbose_debug_output option was NOT passed')
}
// ...
}
Or || and &&:
fn busniness_logic() {
$if verbose_debug_output || another_option ? {
println('verbose_debug_output OR another_option was passed')
}
// ...
}
You can add $else $if or $else which will work as normal conditions:
fn busniness_logic() {
$if verbose_debug_output ? {
println('verbose_debug_output option was passed')
} $else $if another_flag ? {
println('another_option option was passed')
} $else {
println('neither verbose_debug_output nor another_option was passed')
}
// ...
}