Let's start with the smallest possible Slither script:

from slither.slither import Slither  
  
slither = Slither('file.sol')  

A Slither object has:

• contracts (list(Contract): list of contracts
• contracts_derived (list(Contract): list of contracts that are not inherited by another contract (subset of contracts)
• get_contract_from_name (str): Return a contract from its name

contracts_derived iterates over contracts that are not inherited. It is useful to prevent duplicate findings. If you find an issue in a derived contract, then one of its inherited contracts is likely to have the same issue.

A Contract object has:

• name (str): Name of the contract
• functions (list(Function)): List of functions
• modifiers (list(Modifier)): List of functions
• all_functions_called (list(Function/Modifier)): List of all the internal functions reachable by the contract
• inheritance (list(Contract)): List of inherited contracts
• get_function_from_signature (str): Return a Function from its signature
• get_modifier_from_signature (str): Return a Modifier from its signature
• get_state_variable_from_name (str): Return a StateVariable from its name

A Function or a Modifier object has:

• name (str): Name of the function
• nodes (list(Node)): List of the nodes composing the CFG of the function/modifier
• entry_point (Node): Entry point of the CFG
• variables_read (list(Variable)): List of variables read
• variables_written (list(Variable)): List of variables written
• state_variables_read (list(StateVariable)): List of state variables read (subset of variables`read)
• state_variables_written (list(StateVariable)): List of state variables written (subset of variables`written)

Variables can be different types, such as StateVariable, or LocalVariable. All variables have:

• name (str): Name of the variable
• initialized (boolean): True if the variable is initialized at declaration

A Node object has:

• type (NodeType): The type of the node (ex: If a control flow node, RETURN is for the node containing the return statement).
• expression (Expression): Expression associated with the node (not all nodes contain an expression)
• variables_read (list(Variable)): List of variables read
• variables_written (list(Variable)): List of variables written
• state_variables_read (list(StateVariable)): List of state variables read (subset of variables_read)
• state_variables_written (list(StateVariable)): List of state variables written (subset of variables_written)

An Expression is an AST-based representation of the code executed.

For example, the following code explores all the functions of all the contracts and prints what state variables are read or written:

from slither.slither import Slither  
  
slither = Slither('file.sol')  
  
for contract in slither.contracts:  
    print 'Contract: '+ contract.name  
  
    for function in contract.functions:  
        print('Function: {}'.format(function.name))  
  
        print('\tRead: {}'.format([v.name for v in function.state_variables_read]))  
        print('\tWritten {}'.format([v.name for v in function.state_variables_written]))

You will find more Slither API examples here. For example:

• functions_writing.py: Where the state variable a is written?
• variable_in_condition.py: Is the variable a used in a condition?
• functions_called.py: What are all the functions reached by a call to entry_point()?
• slithIR.py: Print the SlithIR operations