Observing State
Observe statement is used to capture values from the state and sets it to a value.
observe map <- ModMutate.State.num:
If an observe statement ends with an ‘:’ sign then it can have a body in which the value that has been observed can be used. If a variable is not declared in advance the value is lost after the observe statement.
Multiple targets and values can be listed in a single statement, e.g.
observe name, symbol <- Mod.State.name, Mod.State.symbol
Mutating State
Mutate statement is used to set a module value to the state.
mutate n -> ModMutate.State.check
In this case the the value in ‘n’ is set to the check field of the persistent state.
mutate num <- ModMutate.State.num:
If a mutate statement ends with a ‘:’ then the statement can have a context block. In the the case of the mutate statement with a context the final value of num after execution of the block is set back into the persistent state at the end of the mutation context. num can’t be a variable name that’s already declared and it’s local to the mutate block.
As with observe, mutate accepts multiple targets & values in a statement.
coco ModMutate
state persistent:
num Map[String]U64
check U64
endpoint deployer Init!():
pass
endpoint invokable Sum!(num1 U64, str String):
mutate num <- ModMutate.State.num:
num[str] += num1
endpoint invokable Num() -> (output Map[String]U64):
observe output <- ModMutate.State.num
endpoint invokable Numplusone(str String) -> (output U64):
observe map <- ModMutate.State.num:
output = map[str] + 1
endpoint invokable SetCheck!(n U64):
mutate n -> ModMutate.State.check