Storage

A storage attribute indicates the purity of a function i.e. whether it:

• reads from storage
• writes to storage
• reads from and writes to storage
• does not read or write (is pure)

When a function is pure the annotation is omitted otherwise the correct annotation must be placed above the function signature.

More information about storage can be found in the common storage operations section.

Reading from Storage

When we read from storage we use the read keyword.

#[storage(read)]

Writing to Storage

When we write to storage we use the write keyword.

#[storage(write)]

Reading & Writing

When we read from and write to storage we use the read & write keywords.

#[storage(read, write)]