How do you define constants with the same name but for differents networks?

Question

I'd like to define something like:

pub mod mints {
    use solana_program::{pubkey, pubkey::Pubkey};
    pub const USDC: Pubkey = pubkey!("key");
}

But then be able to access it with mints::USDC and have the value be environment dependent.

Is this possible? How do I achieve this with either just solana/rust or within Anchor?

Answer 1

I personally use the env! and option_env! macros, then set an environment variable e.g. MAINNET when I want to build for mainnet and assume devnet otherwise.

Combined with just to set env-vars it works pretty well, e.g. you can setup a command just build-bpf-mainnet as MAINNET=1 cargo build-bpf

This way it's pretty easy to setup constants for different mints:

pub fn is_mainnet() -> bool {
    option_env!("MAINNET").is_some()
}

pub struct Mint {
    dev: Pubkey,
    main: Pubkey,
}

impl Mint {
    pub fn pubkey(&self) -> Pubkey {
        if is_mainnet() {
            self.main
        } else {
            self.dev
        }
    }
}

pub const USDC: Mint = Mint {
    main: pubkey!("EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"),
    dev: pubkey!("4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU"),
};

pub const LIKE: Mint = Mint {
    main: pubkey!("3bRTivrVsitbmCTGtqwp7hxXPsybkjn4XLNtPsHqa3zR"),
    dev: pubkey!("8KM7nEzUebxtnJ1BRbbnh58Bnm1ZCtmCsp1xW1zYsuWp"),
};

I tried looking for a way for on-chain programs to determine dev/local/mainnet recently but couldn't find any.

Answer 2

this library might might help?

confy