basic_info_getter.sol

/* From https://raw.githubusercontent.com/fivedogit/solidity-baby-steps/master/contracts/15_basic_info_getter.sol
 * This is a demonstration of the various global variables available to contracts.
 *	This list is probably not exhaustive, especially weeks and months from now. (9/2015) */

pragma solidity ^0.4.18;

contract basicInfoGetter {
  address creator;

  constructor() public {
    creator = msg.sender;
  }

  function getCurrentMinerAddress() public view returns (address) { // get CURRENT block miner's address,
    // not necessarily the address of the miner when this block was born
    return block.coinbase;
  }

  function getCurrentDifficulty() public view returns (uint) {
    return block.difficulty;
  }

  function getCurrentGaslimit() public view returns (uint) { // the most gas that can be spent on any given transaction right now
    return block.gaslimit;
  }

  function getCurrentBlockNumber() public view returns (uint) {
    return block.number;
  }

  function getBlockTimestamp() public view returns (uint) { // returns current block timestamp in SECONDS (not ms) from epoch
    return block.timestamp;
    // also "now" == "block.timestamp", as in "return now;"
  }

  function getMsgData() public pure returns (bytes) {   // The data of a call to this function. Always returns "0xc8e7ca2e" for me.
    // adding an input parameter would probably change it with each diff call?
    return msg.data;
  }

  function getMsgSender() public view returns (address) { // Returns the address of whomever made this call
    // (i.e. not necessarily the creator of the contract)
    return msg.sender;
  }

  function getMsgValue() public payable returns (uint) {   // returns amt of wei sent with this call
    return msg.value;
  }

  /***  A note about gas and gasprice:
   Every transaction must specify a quantity of "gas" that it is willing to consume (called startgas),
   and the fee that it is willing to pay per unit gas (gasprice). At the start of execution,
   startgas * gasprice ether are removed from the transaction sender's account.
   Whatever is not used is immediately refunded.
   */

  function getMsgGas() public view returns (uint) {
    return gasleft();
  }

  function getTxGasprice() public view returns (uint) {
    return tx.gasprice; // "gasprice" is the amount of gas the sender was *willing* to pay. 50000000 for me. (geth default)
  }

  function getTxOrigin() public view returns (address) { // returns sender of the transaction
  // What if there is a chain of calls? I think it returns the first sender, whoever provided the gas.
    return msg.sender;
  }

  function getContractAddress() public view returns (address) {
    return this;
  }

  function getContractBalance() public view returns (uint) {
    return address(this).balance;
  }

  /**********
   Standard kill() function to recover funds
   **********/

  function kill() public {
    if (msg.sender == creator)
    selfdestruct(creator);
    // kills this contract and sends remaining funds back to creator
  }
}