Trait Context 

pub trait Context {
    // Required methods
    fn trap(&self, message: &str) -> !;
    fn print<S: AsRef<str>>(&self, s: S);
    fn id(&self) -> Principal;
    fn time(&self) -> u64;
    fn balance(&self) -> u64;
    fn caller(&self) -> Principal;
    fn msg_cycles_available(&self) -> u64;
    fn msg_cycles_accept(&self, amount: u64) -> u64;
    fn msg_cycles_refunded(&self) -> u64;
    fn stable_store<T>(&self, data: T) -> Result<(), Error>
       where T: ArgumentEncoder;
    fn stable_restore<T>(&self) -> Result<T, String>
       where T: for<'de> ArgumentDecoder<'de>;
    fn call_raw<S: Into<String>>(
        &'static self,
        id: Principal,
        method: S,
        args_raw: Vec<u8>,
        cycles: u64,
    ) -> CallResponse<Vec<u8>>;
    fn set_certified_data(&self, data: &[u8]);
    fn data_certificate(&self) -> Option<Vec<u8>>;
    fn spawn<F: 'static + Future<Output = ()>>(&mut self, future: F);
    fn stable_size(&self) -> u32;
    fn stable_grow(&self, new_pages: u32) -> Result<u32, StableMemoryError>;
    fn stable_write(&self, offset: u32, buf: &[u8]);
    fn stable_read(&self, offset: u32, buf: &mut [u8]);
    fn with<T: 'static + Default, U, F: FnOnce(&T) -> U>(
        &self,
        callback: F,
    ) -> U;
    fn maybe_with<T: 'static, U, F: FnOnce(&T) -> U>(
        &self,
        callback: F,
    ) -> Option<U>;
    fn with_mut<T: 'static + Default, U, F: FnOnce(&mut T) -> U>(
        &self,
        callback: F,
    ) -> U;
    fn maybe_with_mut<T: 'static, U, F: FnOnce(&mut T) -> U>(
        &self,
        callback: F,
    ) -> Option<U>;
    fn take<T: 'static>(&self) -> Option<T>;
    fn swap<T: 'static>(&self, value: T) -> Option<T>;
    fn store<T: 'static>(&self, data: T);
    fn get_maybe<T: 'static>(&self) -> Option<&T>;
    fn get<T: 'static + Default>(&self) -> &T;
    fn get_mut<T: 'static + Default>(&self) -> &mut T;
    fn delete<T: 'static + Default>(&self) -> bool;

    // Provided methods
    fn call<T: ArgumentEncoder, R: for<'a> ArgumentDecoder<'a>, S: Into<String>>(
        &'static self,
        id: Principal,
        method: S,
        args: T,
    ) -> CallResponse<R> { ... }
    fn call_with_payment<T: ArgumentEncoder, R: for<'a> ArgumentDecoder<'a>, S: Into<String>>(
        &'static self,
        id: Principal,
        method: S,
        args: T,
        cycles: u64,
    ) -> CallResponse<R> { ... }
}

Required Methods

fn trap(&self, message: &str) -> !

Trap the code.

fn print<S: AsRef<str>>(&self, s: S)

Print a message.

fn id(&self) -> Principal

ID of the current canister.

fn time(&self) -> u64

The time in nanoseconds.

fn balance(&self) -> u64

The balance of the canister.

fn caller(&self) -> Principal

The caller who has invoked this method on the canister.

fn msg_cycles_available(&self) -> u64

Return the number of available cycles that is sent by the caller.

fn msg_cycles_accept(&self, amount: u64) -> u64

Accept the given amount of cycles, returns the actual amount of accepted cycles.

fn msg_cycles_refunded(&self) -> u64

Return the cycles that were sent back by the canister that was just called. This method should only be called right after an inter-canister call.

fn stable_store<T>(&self, data: T) -> Result<(), Error>

where T: ArgumentEncoder,

Store the given data to the stable storage.

fn stable_restore<T>(&self) -> Result<T, String>

where T: for<'de> ArgumentDecoder<'de>,

Restore the data from the stable storage. If the data is not already stored the None value is returned.

fn call_raw<S: Into<String>>( &'static self, id: Principal, method: S, args_raw: Vec<u8>, cycles: u64, ) -> CallResponse<Vec<u8>>

Perform a call.

fn set_certified_data(&self, data: &[u8])

Set the certified data of the canister, this method traps if data.len > 32.

fn data_certificate(&self) -> Option<Vec<u8>>

Returns the data certificate authenticating certified_data set by this canister.

fn spawn<F: 'static + Future<Output = ()>>(&mut self, future: F)

Execute a future without blocking the current call.

fn stable_size(&self) -> u32

Returns the current size of the stable memory in WebAssembly pages. (One WebAssembly page is 64KiB)

fn stable_grow(&self, new_pages: u32) -> Result<u32, StableMemoryError>

Tries to grow the memory by new_pages many pages containing zeroes. This system call traps if the previous size of the memory exceeds 2^32 bytes. Errors if the new size of the memory exceeds 2^32 bytes or growing is unsuccessful. Otherwise, it grows the memory and returns the previous size of the memory in pages.

fn stable_write(&self, offset: u32, buf: &[u8])

Writes data to the stable memory location specified by an offset.

fn stable_read(&self, offset: u32, buf: &mut [u8])

Reads data from the stable memory location specified by an offset.

fn with<T: 'static + Default, U, F: FnOnce(&T) -> U>(&self, callback: F) -> U

Pass an immutable reference of data with type T to the callback, stores the default value if not present, and return the transformation.

fn maybe_with<T: 'static, U, F: FnOnce(&T) -> U>( &self, callback: F, ) -> Option<U>

Pass an immutable reference of data with type T to the callback, and return the mapped value.

fn with_mut<T: 'static + Default, U, F: FnOnce(&mut T) -> U>( &self, callback: F, ) -> U

Pass the mutable reference of data with type T to the callback, stores the default value if not present, and return the transformation.

fn maybe_with_mut<T: 'static, U, F: FnOnce(&mut T) -> U>( &self, callback: F, ) -> Option<U>

Pass the mutable reference of data with type T to the callback, and return the callback’s result.

fn take<T: 'static>(&self) -> Option<T>

Remove the data associated with the given type, and return it.

fn swap<T: 'static>(&self, value: T) -> Option<T>

Replaced the stored value of type T with the new provided one and return the old one if any.

fn store<T: 'static>(&self, data: T)

👎Deprecated

See ic::store

fn get_maybe<T: 'static>(&self) -> Option<&T>

👎Deprecated

See ic::store

fn get<T: 'static + Default>(&self) -> &T

👎Deprecated

See ic::store

fn get_mut<T: 'static + Default>(&self) -> &mut T

👎Deprecated

See ic::store

fn delete<T: 'static + Default>(&self) -> bool

👎Deprecated

See ic::store

Provided Methods

fn call<T: ArgumentEncoder, R: for<'a> ArgumentDecoder<'a>, S: Into<String>>( &'static self, id: Principal, method: S, args: T, ) -> CallResponse<R>

Perform the call and return the response.

fn call_with_payment<T: ArgumentEncoder, R: for<'a> ArgumentDecoder<'a>, S: Into<String>>( &'static self, id: Principal, method: S, args: T, cycles: u64, ) -> CallResponse<R>

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl Context for MockContext