lang: remove default space calc

[paul-schaaf]

closes #1563

force usage of the space constraint with init

[paul-schaaf]

I remember us talking about this but just wanted to check whether you still think this should be done before I continue? @armaniferrante

[armaniferrante]

I remember us talking about this but just wanted to check whether you still think this should be done before I continue? @armaniferrante

I'm for it.

[paul-schaaf]

what do you think about adding a len attribute #[len(50)]. Alternatively we could add #[len(x)] attributes on each field. If it's not given on the field, try to infer it. e.g. u64 -> 8. len should be its own attribute and not be an attribute only on #[account] so it can also be used with types that only implement serialize traits

that would then generate a

impl #name {
    pub const LEN: usize = #sum_lengths;
}

If we do this, we'd better do it in a different PR but in the same release imo.

[armaniferrante]

what do you think about adding a len attribute

Happy to discuss it in an issue. At first glance, I'm not super excited about it and would rather explicitly state the length via space.

[armaniferrante]

Let's wait to merge this until after the next patch release.

[armaniferrante]

No need to change this. But generally I'm not a fan of these comments. They don't really add any useful information.

[paul-schaaf]

• writing the individual parts down explicitly before summing them up reduces likelihood of mistakes
• it becomes easier to parse mentally because you dont need to go through the calculation steps again. Then again, how often do you need to parse the space of an account? probably not often.

[armaniferrante]

• the second bullet point is better solved imo by having a cumulative sum comment rather than saying the iindividual sizes.

[utx0]

Whats the reasoning for removing this? Was quite a handy feature for me?

[paul-schaaf]

@utx0 reasoning is in the issue

[daweth]

is there a guide on how to calculate account space?

[ronanyeah]

I usually have something like this:

use anchor_client::anchor_lang::AnchorSerialize;

fn main() {
    let pubkey = str::parse::<Pubkey>("11111111111111111111111111111111").unwrap();

    let value = your_program::YourStruct {
        pubkey_option: Some(pubkey),
        integer: u64::MAX,
    };

    println!("size: {}", value.try_to_vec().unwrap().len());
}

[utx0]

is there a guide on how to calculate account space?

I am doing this:

    #[account(
        init,
        space = 8 + mem::size_of::<PoolState>(),
        payer = payer,
        seeds = [ POOL_STATE_SEED, lp_token_mint.key().as_ref() ],
        bump,
    )]
    pub pool_state: Box<Account<'info, PoolState>>,

[paul-schaaf]

there is a guide in the book. https://book.anchor-lang.com/chapter_5/space.html

@utx0 we recommend not using mem::size_of. (see the tic-tac-toe milestone project in the book for an explanation)

also, going forward, please dont use issues to discuss support questions and use the discord instead. https://discord.gg/rnNpg7Ys.