Ethereum Cookbook

How to do it…

1. Create a library in the same way a contract is defined, but with the library keyword:

libary libName {    //....}

2. Consider the following differences while creating a library contract:

• Libraries cannot have any state variables
• Libraries cannot inherit nor be inherited
• Libraries cannot have a fallback or payable functions to receive Ether

3. Invoke the library functions like invoking external contract calls:

<library>.<function>();

4. Calling a function in the library will use the delegatecall instruction. This allows the code to execute in the context of the caller:

library lib {    function getBal() returns (uint) {        return address(this).balance;    }}contract Sample {    function getBalance() returns (uint) { return lib.getBal(); ...