simplified crowdfunding solidity

crowdfunding.sol

pragma solidity ^0.4.8;

contract Crowdfunding {

  enum Stages {
    Initialization,
    CampaignInprogress,
    CampaignFailure,
    CampaignSuccess
  }
  
    enum Actors {
        Contributor
    }
    
    mapping (address => uint) public contributorList;

  // current stage
  Stages public stage = Stages.Initialization;
  
  // contract creator is beneficiary
  address public beneficiary;

  // (in wei)
  uint256 public fundingGoal;

  // (in wei)
  uint256 public amountRaised;

  // the current campaign expiry (future block number)
  uint256 public expiry;
  

  // the contributions data store, where all contributions are notated
  address[] public contributorsList;


  // all contribution a specific sender
  mapping(address => uint256) public contributions;
  

  // the contract constructor
  function Campaign(uint256 _fundingGoal, uint256 _expiry)  public {

    expiry = _expiry;
    fundingGoal = _fundingGoal;
    beneficiary = msg.sender;
    
    contributorList[0xADc997Fe0Bf47f50df2F2AA56d042ee4ab74cc11] = 1;
    
    from_initialisation_to_campaigninprogress();
  }
  
   function from_initialisation_to_campaigninprogress() {
    if (block.number < expiry && amountRaised < fundingGoal) {
        stage = Stages.CampaignInprogress;
    } 
  }
  
  function contribute() payable atStage(Stages.CampaignInprogress) onlyContributor {
    if (msg.value == 0) {
        throw;
    }
    
    bool isKwnownContributor = (contributions[msg.sender] > 0);
    
    if(!isKwnownContributor)
    {
        contributorsList.push(msg.sender);
    }
  
    contributions[msg.sender] += msg.value;
    amountRaised += msg.value;
    from_campaigninprogress_to_campaignsuccess();
    from_campaigninprogress_to_campaignfailure();
    
  }
  
  function from_campaigninprogress_to_campaignsuccess() {
    //if(block.number >= expiry && amountRaised >= fundingGoal) {
  if(amountRaised >= fundingGoal) {
         stage = Stages.CampaignSuccess;
         payout();
    }
  }
  
  function from_campaigninprogress_to_campaignfailure() {
      if(block.number >= expiry && amountRaised < fundingGoal) {
          stage = Stages.CampaignFailure;
          refundcontributors();
      }
  }
  
  function payout() atStage(Stages.CampaignSuccess) internal{
    // send funds to the benerifiary
    if (!beneficiary.call.value(this.balance)()) {
      throw;
    }
  }
  
  function refundcontributors() atStage(Stages.CampaignFailure) internal{
      for (var i = 0; i < contributorsList.length; i++) {
        address contrib = contributorsList[i];
        contrib.send(contributions[contrib]);
    }  
  }
  
  // check the campaign state
  modifier atStage(Stages _expectedStage) {
    require(stage == _expectedStage);
    _;
  }
    
    modifier onlyContributor {
      require(contributorList[msg.sender] != 0);
      _;
    }
}

remove unused actors