Here is an article with explanations and examples on how to conditionally set the program_id parameter in the declare_id! macro:

Conditional Program IDs in Anchor Declarations

In Anchor, you can use the declare_id! macro to create a program identifier that can be used in different versions. One common use case is if you want to deploy your application differently depending on whether it is running in production or staging mode.

Basic Usage

Let’s first look at how you can conditionally set the program_id parameter using the declare_id! macro:

use anchor_lang::declares;
#[derive(AnchorProgram)]
pub mod my_program {
declare_id!("3gHtqUaKGu3RJCWVbgQFd5Gv4MQfQKmQjKSvdejkLoA6");
}

In this example, “program_id” is hardcoded as “3gHtqUaKGu3RJCWVbgQFd5Gv4MQfQKmQjKSvdejkLoA6”, which will always be used.

Using a constant

To make the code more readable and easier to maintain, you can define a constant for the “program_id” parameter:

use anchor_lang::declares;
const PROGRAM_ID: &str = "3gHtqUaKGu3RJCWVbgQFd5Gv4MQfQKmQjKSvdejkLoA6";
#[derive(AnchorProgram)]
pub mod my_program {
declare_id!(&PROGRAM_ID);
}

In this example, the constant PROGRAM_ID is defined and used in the macro declare_id!.

Using a variable

If you need to use the program ID as a variable, you can define it using the “program_id” type:

use anchor_lang::declares;
pub const PROGRAM_ID: &str = get_program_id();

And then use it in the macro declare_id!

#[derive(AnchorProgram)]
pub mod my_program {
declare_id!(PROGRAM_ID);
}

Staging builds

To create staged builds, you can use the “program_id” parameter to conditionally set the program ID. For example, let’s say you have a function that depends on the program ID:

use anchor_lang::declares;
fn my_function(program_id: &str) -> Result<(), AnchorError> {
//...
}

You can define a staging build using the “program_id” parameter, like this:

#[derive(AnchorProgram)]
pub mod my_program {
declare_id!(if_staging() { PROGRAM_ID } else { get_program_id() });
#[function]
pub fn my_function(program_id: &str) -> Result<(), AnchorError> {
//...
}
}

In this example, the function “my_function” will use the program ID defined in the staging build if it is executed in a staging build.

Conclusion

Using the macro declare_id! and by defining constants or variables for program IDs, you can create more flexible and maintainable code that adapts to different versions. Remember to always follow the anchor documentation guidelines when writing your code.