Message mode

As you might've noticed, messages are sent with the mode param of a struct SendParameters. It's an Int value, which is combined from base modes and optional flags, which are also Int values.

It's possible to use raw Int values and manually provide them for the mode, but for your convenience there's a set of constants which you may use to construct the compound mode with ease. Take a look at the following tables for more information on base modes and optional flags.

Base modes

Optional flags

Combining modes with flags

To make the Int value for mode field of SendParameters, you just have to combine base modes with optional flags by adding them together as numbers.

For example, if you want to send a regular message and pay transfer fees separately, use the mode $0$ (default) and a flag $+1$ to get mode $= 1$, which is equal to just use SendPayGasSeparately constant.

Alternatively, if you want to send the whole contract balance and destroy it immediately, use the mode $128$ and flag $+32$ to get mode $= 160$, which is equal to SendRemainingBalance + SendDestroyIfZero.

Here's how the latter example would look in code:

let to: Address = ...;
let value: Int = ton("1");
send(SendParameters{
    to: to,
    value: value,
    mode: SendRemainingBalance + SendDestroyIfZero,
    body: "Hello, World!".asComment()
});