Voting
Category
real language
Bookmarking
Language Ada
(multitasking)
| Date: | 04/20/05 |
| Author: | tmoran[at]bix[dot]com |
| URL: | n/a |
| Comments: | 0 |
| Info: | n/a |
| Score: |  (3.94 in 240 votes) |
-- Just for amusement, here's a multi-tasking version.
-- Ten customers enter bar to sing and drink. Bartender serializes
-- access to 'take one down' to avoid fights
-- contributed by tmoran@bix.com
with Text_IO;
procedure Bar is
Out_Of_Beer : Exception;
protected Bartender is
function Count return Integer;
procedure Take_One_Down;
private
Remaining : Integer range 0 .. 99 := 99;
end Bartender;
protected body Bartender is
function Count return Integer is
begin return Remaining; end Count;
procedure Take_One_Down is
begin
if Remaining = 0 then raise Out_Of_Beer;
else Remaining := Remaining - 1;
end if;
end Take_One_Down;
end Bartender;
type Names is (Charles, Ada, John, Grace, Donald,
Edsger, Niklaus, Seymour, Fred, Harlan);
task type Customers is
entry Enter_Bar(Who : in Names);
end Customers;
Customer_List : array(Names) of Customers;
task body Customers is
Me : Names;
procedure Sing_And_Drink(Singer_ID : in String) is
procedure Sing(S : in String) renames Text_IO.Put_Line;
begin
loop
declare
Bottle_Part : constant String
:= Integer'image(Bartender.Count) & " bottles of beer";
begin
Sing(Bottle_Part & " on the wall" & Singer_ID);
Sing(Bottle_Part & Singer_ID);
end;
Sing(" Take one down and pass it arround" & Singer_ID);
Bartender.Take_One_Down;
delay 10.0; -- allow ten seconds to gulp one down
end loop;
exception
when Out_Of_Beer => Sing("no more beer!" & Singer_ID);
end Sing_And_Drink;
begin -- customer task
accept Enter_Bar(Who : in Names) do
Me := Who;
end Enter_Bar;
Sing_And_Drink(" - " & Names'image(Me));
end Customers;
begin -- operating bar
for Person in Customer_List'range loop
Customer_List(Person).Enter_Bar(Person);
delay 2.0; -- allow two seconds between customers entering bar
end loop;
end Bar;
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