flag.read_context: A function, a constant or other pure code reads a flag, which only an action, a test or a route's run: can

A function, a constant or other pure code reads a flag, which only an action, a test or a route's run: can.

Area 16, Built-in services; not declinable; the next step is usually the agent's.

Why Jadpo refuses it

A flag's value is worked out for whoever is calling, and can change while the app runs. A function gives the same result for the same arguments, so a flag read inside one would make it give different answers for the same call, and its tests would no longer say what it does.

What it looks like

example

type CheckoutSteps = Int {    min: 1    max: 3}flags {    new_checkout: Bool {        default: false        owner: "payments"        expires: "2099-01-31"    }}function checkout_steps() -> CheckoutSteps {    if (flags.new_checkout) {        return 1    }    return 3}

jadpo checkcheck failed: 1 error, 1 file

error A function can't read flags.new_checkout

--> main.jadpo:15:9

   |15 |     if (flags.new_checkout) {   |         ^^^^^^^^^^^^^^^^^^ reads a flag

reason: A flag's value is worked out for the caller while the app runs, and a function gives the same result for the same arguments, so it can't read one; an action reads it and passes its value in as a parameter.
next: Read flags.new_checkout in the action that calls this, and pass its value as a parameter (agent)
rule: flag.read_context
help: https://jadpo.dev/docs/errors/flag.read_context

(agent) at the end of the next: line means your coding agent can make the fix itself.

How to fix it

If the function's callers are actions, read the flag there and pass its value in:

example

function checkout_steps(new_checkout: OnePage) -> CheckoutSteps {    if (new_checkout) {        return 1    }    return 3}action start_checkout() -> CheckoutSteps {    return checkout_steps(OnePage(flags.new_checkout))}

checkout_steps is pure again, and its tests can pass it either value.

Why Jadpo refuses it

What it looks like

How to fix it

Related