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Contents
unit uBankAccount;
interface
uses System.SysUtils;
type
EAccountNotOpen = class(Exception);
IBankAccount = interface(IInvokable)
['{5DA23C52-A1D1-4FBE-8601-1CF194B2C372}']
function GetBalance: Double;
procedure UpdateBalance(aValue: Double);
procedure Open;
procedure Close;
property Balance: Double read GetBalance;
end;
TBankAccount = class(TInterfacedObject, IBankAccount)
private
fLock: TMREWSync;
fBalance: Double;
fIsOpen: Boolean;
function GetBalance: Double;
public
constructor Create;
destructor Destroy; override;
procedure Open;
procedure Close;
procedure UpdateBalance(aValue: Double);
property Balance: Double read GetBalance;
end;
implementation
constructor TBankAccount.Create;
begin
inherited create;
fLock := TMREWSync.Create;
fBalance := 0;
fIsOpen := false;
end;
destructor TBankAccount.Destroy;
begin
fLock.Free;
inherited Destroy;
end;
procedure TBankAccount.Open;
begin
fLock.BeginWrite;
try
fIsOpen := true;
finally
fLock.EndWrite;
end;
end;
procedure TBankAccount.Close;
begin
fLock.BeginWrite;
try
fIsOpen := false;
finally
fLock.EndWrite;
end;
end;
function TBankAccount.GetBalance;
begin
fLock.BeginRead;
try
if not fIsOpen then
raise EAccountNotOpen.Create('Cannot get balance on an account that isn''t open');
result := fBalance;
finally
fLock.EndRead;
end;
end;
procedure TBankAccount.UpdateBalance(aValue: Double);
begin
fLock.BeginWrite;
try
if not fIsOpen then
raise EAccountNotOpen.Create('Cannot update balance on an account that isn''t open');
fBalance := fBalance + aValue;
finally
fLock.EndWrite;
end;
end;
end.
Version data entries
346 entries across 346 versions & 1 rubygems