WEBVTT

1
00:00:01.580 --> 00:00:05.100
so just before we start a challenge
there's one little bugs that I want to fix

2
00:00:05.100 --> 00:00:08.490
and I just want to run it again and show you
what the bug was and you probably picked this up

3
00:00:08.490 --> 00:00:15.030
in the last video so when we first start the dealer

4
00:00:15.030 --> 00:00:19.990
score is showing 0 obviously the player scores
working and the reason that's doing that

5
00:00:19.990 --> 00:00:25.330
if you closes this down and on the code on the bottom we've got the deal player

6
00:00:25.330 --> 00:00:30.410
we call the deal_player function and we actually add the card to the

7
00:00:30.410 --> 00:00:35.010
dealer hand and notice we are not calling a
function to print it to display anything

8
00:00:35.010 --> 00:00:40.410
or anything along those lines whereas the deal_player function is sort of

9
00:00:40.410 --> 00:00:43.230
self-contained and also outputs the
actual

10
00:00:43.230 --> 00:00:47.360
scores as well on the screen so what we
want to do is make quick changes there

11
00:00:47.360 --> 00:00:58.750
to actually show this score so its gonna be
dealer.....

12
00:00:58.750 --> 00:01:06.010
...so basically we are just going
to display that's score so we've drawn a

13
00:01:06.010 --> 00:01:09.500
card and we are going to show that on the screen once and then obviously

14
00:01:09.500 --> 00:01:13.090
subsequent times its going to work
automatically when we click the dealer

15
00:01:13.090 --> 00:01:17.130
button so if we run again now that should fix that so we got an

16
00:01:17.130 --> 00:01:23.560
initial score and you can see its better now we got it working even

17
00:01:23.560 --> 00:01:27.820
though the functions still work in that
once we pressed deal it is still going

18
00:01:27.820 --> 00:01:31.880
to calculate this is a better way of
actually showing and obviously I got

19
00:01:31.880 --> 00:01:39.100
slaughtered by dealer ok so that's
working so talking a little  bit about the challenge

20
00:01:39.100 --> 00:01:44.240
its is going to be quite simple because just looking
at where we're at with the game now it

21
00:01:44.240 --> 00:01:48.340
plays a reasonably good game of blackjack
and all the dealing is now taking

22
00:01:48.340 --> 00:01:54.190
care of by the computer so we only need to
click on dealer once we are finish with our turn and the

23
00:01:54.190 --> 00:01:56.550
rest of the game finishes and the deal

24
00:01:56.550 --> 00:02:01.200
function deal_dealer function sort of handles that functionality to play the

25
00:02:01.200 --> 00:02:03.560
game as far as a computer the is concern

26
00:02:03.560 --> 00:02:06.710
their is a bit of annoying though which you see me to do having
to close the window and run the

27
00:02:06.710 --> 00:02:10.580
program again for a new game and I
mentioned in the last video it's time

28
00:02:10.580 --> 00:02:12.360
for a challenge so

29
00:02:12.360 --> 00:02:16.300
just before I do that one final comment about
global variables you probably sick about

30
00:02:16.300 --> 00:02:19.450
it now but we are harping on about it because
it's really important that you

31
00:02:19.450 --> 00:02:26.050
understand this and get it to the right mind set about how to use them so you are aware of the

32
00:02:26.050 --> 00:02:30.530
limitations you might be wondering why
the variables player_hand

33
00:02:30.530 --> 00:02:34.990
and dealer_hand are not triggering
warnings about a local variable shadowing

34
00:02:34.990 --> 00:02:38.720
the global ones because both the deal_player function if we go back and

35
00:02:38.720 --> 00:02:45.700
have a look at that as you can see the deal_player function on line 78 and

36
00:02:45.700 --> 00:02:50.170
the deal_dealer function
on line 64 they are both appending new

37
00:02:50.170 --> 00:02:54.459
cards to the corresponding list so
wouldn't that count as modifying the

38
00:02:54.459 --> 00:02:57.940
global variable in which make them local
because we talked about that in previous

39
00:02:57.940 --> 00:02:59.260
videos

40
00:02:59.260 --> 00:03:05.020
well the answer is that neither variable
is modified their initialized as lists

41
00:03:05.020 --> 00:03:08.130
if you go down and have a look

42
00:03:08.130 --> 00:03:15.010
we got player_hand and dealer_hand is initialization as you can see here in

43
00:03:15.010 --> 00:03:22.049
line 152 and 153 and continue to reference
the same lists as long as the program

44
00:03:22.049 --> 00:03:26.830
runs so adding items to list or removing
items from it is not modifying the list

45
00:03:26.830 --> 00:03:31.150
variable it always has the same value
which is a list and the contents of a list

46
00:03:31.150 --> 00:03:36.340
can change now adding items to a global
list is still a side effect but its not

47
00:03:36.340 --> 00:03:41.049
considered as dangerous as changing the
list of the variable holds for example

48
00:03:41.049 --> 00:03:46.360
lists exists to have items added and
removed and so consequently this is

49
00:03:46.360 --> 00:03:49.470
acceptable behavior and that's why
IntelliJ is not actually warning of us

50
00:03:49.470 --> 00:03:53.890
of that so it would still probably better to
pass the lists arguments to the

51
00:03:53.890 --> 00:03:58.700
functions but as we can't provide parameters to functions that are used as button

52
00:03:58.700 --> 00:04:02.410
commands we really don't have any choice
here but to use global list so that of

53
00:04:02.410 --> 00:04:07.890
course why we went ahead and did that ok so
moving on now the challenge and its going to be

54
00:04:07.890 --> 00:04:11.989
quite a simple one the challenges is to
add a new button to the program with the

55
00:04:11.989 --> 00:04:16.930
text new game now the button should call a
function that clears the cards from the

56
00:04:16.930 --> 00:04:22.590
screen it resets the players and dealers
hands and then starts a new game now the

57
00:04:22.590 --> 00:04:24.360
easiest way to clear the contents of a

58
00:04:24.360 --> 00:04:29.270
frame is to destroy the frame and create
a new one with the same name and in fact

59
00:04:29.270 --> 00:04:34.210
that's why the program has a player_card_frame and dealer_card_frame

60
00:04:34.210 --> 00:04:40.199
inside the card frame
itself so that's it go away and create a

61
00:04:40.199 --> 00:04:44.990
new button with the text new game and again the functionality clear the cards

62
00:04:44.990 --> 00:04:48.629
from the Screen reset the player and
dealers hands and then start a new game so

63
00:04:48.629 --> 00:04:54.939
pause the video go away and see if you can come up with
a solution and when you're ready to see

64
00:04:54.939 --> 00:04:58.529
our version of it come back and and I'll go through that with you pause the video now.....

65
00:05:03.080 --> 00:05:04.480
...ok so hopefully you

66
00:05:04.480 --> 00:05:09.240
managed to figure it out and have a
pretty good going getting it working so let's go through

67
00:05:09.240 --> 00:05:14.360
what our solution is to implement this and
what we're going to do is create a new

68
00:05:14.360 --> 00:05:20.470
function called new_game now the thing to remember here is
the most of the initialization code in

69
00:05:20.470 --> 00:05:24.540
the main program concern setting up the GUI and so consequently we don't need to

70
00:05:24.540 --> 00:05:29.130
repeat all of that every time a new game
started but the deal_card_frame

71
00:05:29.130 --> 00:05:34.930
and player_card_frame will need to be cleared so

72
00:05:34.930 --> 00:05:38.870
calling the destroy method will do that
and once that is done the list holding

73
00:05:38.870 --> 00:05:44.330
the hands rather will need to be cleared and the
first 3 cards dealt and we can also make

74
00:05:44.330 --> 00:05:47.160
a start on that now so let's do that
so I'm going to come down here after

75
00:05:47.160 --> 00:05:58.240
deal_player lets add the method so....and so

76
00:05:58.240 --> 00:06:02.950
we need to reference those global variables....

77
00:06:02.950 --> 00:06:21.810
....

78
00:06:21.810 --> 00:06:28.710
....ok so

79
00:06:28.710 --> 00:06:35.340
first thing we want to do is....

80
00:06:36.170 --> 00:06:50.350
.....

81
00:06:51.010 --> 00:06:59.140
....

82
00:06:59.870 --> 00:07:26.900
....

83
00:07:26.900 --> 00:07:35.870
.....and
what I could have done just scrolling down

84
00:07:35.870 --> 00:07:55.150
is just grab this code again....because its an identical code and obviously I could have done it as well for the dealer frame next we

85
00:07:55.150 --> 00:08:00.350
clear the status of the game at the top wether
dealer wins or the player wins so....

86
00:08:00.350 --> 00:08:07.050
..need to recreate the lists

87
00:08:07.050 --> 00:08:15.430
and what we can do their I can come
down here and just copy this code

88
00:08:15.430 --> 00:08:24.600
copy that and come back up here and paste it in....

89
00:08:27.800 --> 00:08:41.880
...ok so obviously we've cleared
the player hands and dealer hands now and we

90
00:08:41.880 --> 00:08:47.709
deal a new card and we will see also deal a new card for the dealer and another

91
00:08:47.709 --> 00:08:52.420
card for the player again as we've done
previously and obviously because looking

92
00:08:52.420 --> 00:08:56.810
at the code we also need to declare that we
want to use the global objects rather

93
00:08:56.810 --> 00:09:02.560
than creating local variables and that's why
we used to global key word on line

94
00:09:02.560 --> 00:09:08.160
88 to 91 now on Python 3 the 2
lists holding the hands could be cleared

95
00:09:08.160 --> 00:09:13.040
using their .clear method and that just removes
all the items for them but it doesn't create

96
00:09:13.040 --> 00:09:16.680
a new list so we could access to global
variables without declaring them in the

97
00:09:16.680 --> 00:09:21.240
function however we've also written blackjack to work with Python 2 so instead

98
00:09:21.240 --> 00:09:25.610
of that approach what we've done is we assigned empty
lists to the two variables you can see on

99
00:09:25.610 --> 00:09:30.290
line 103 and 104 and that means they do have to
be declared s global and the function

100
00:09:30.290 --> 00:09:35.200
for that to actually work now creating
the button itself is pretty easy we

101
00:09:35.200 --> 00:09:39.120
already have a frame in place so let's add
that down below the initial

102
00:09:39.120 --> 00:09:57.470
initialization code so....

103
00:09:57.470 --> 00:10:00.540
...

104
00:10:03.660 --> 00:10:08.480
....making sure we don't
use the brackets because we don't want

105
00:10:08.480 --> 00:10:13.220
to execute that we just saying this is the
function to call anytime the buttons clicked we are

106
00:10:13.220 --> 00:10:24.640
just gonna call that functionality then need to add it to the grid so.....

107
00:10:24.640 --> 00:10:28.420
....

108
00:10:28.420 --> 00:10:32.790
so that has added the button and just the other thing
we can take because you've notice we've got a lot

109
00:10:32.790 --> 00:10:39.750
of code their that's being used so we can
actually call this new_game function if I

110
00:10:39.750 --> 00:10:45.100
just scroll down I neet to put
some of this back so I'm going to copy

111
00:10:45.100 --> 00:10:55.460
this bit of code here so we need to create those
variables initially down here and once

112
00:10:55.460 --> 00:11:04.920
you've done that we can actually call
the new game functions so I'm gonna do that so....

113
00:11:04.920 --> 00:11:07.870
and what we're trying to do is avoid
duplication of code because we had the

114
00:11:07.870 --> 00:11:12.520
code here that we have originally placed
in there and so basically at the start

115
00:11:12.520 --> 00:11:16.170
of the game we can go through and
just actually run this and we have got

116
00:11:16.170 --> 00:11:20.270
a frame we are actually technically
destroying a frame and created it

117
00:11:20.270 --> 00:11:24.540
creating it again but have what we are
doing is we are avoiding this duplication

118
00:11:24.540 --> 00:11:29.690
of the code and not running it I should say sort of
in two places so the Idea is to put the

119
00:11:29.690 --> 00:11:39.400
code and only executed it only once so lets try running that and see whether it works...

120
00:11:39.400 --> 00:11:45.230
....and so
far so good we've now got another button for a

121
00:11:45.230 --> 00:11:50.180
new game and players 14 so I'm
going to click on play another

122
00:11:50.180 --> 00:11:55.720
card I should say so hit me and I
busted the dealer wins and now I click

123
00:11:55.720 --> 00:12:01.550
new game starting again thats work and
strait away I obviously got blackjack which

124
00:12:01.550 --> 00:12:07.420
is a good thing so I'm going to click on dealer and
I win because the player the dealer

125
00:12:07.420 --> 00:12:08.520
busted

126
00:12:08.520 --> 00:12:11.630
click on new game and click on play

127
00:12:12.590 --> 00:12:14.800
and I got 21 again I'm having a great run here

128
00:12:14.800 --> 00:12:21.560
and the dealer busts so click on new game again I've got 18 so I'm gonna just gonna hold

129
00:12:21.560 --> 00:12:27.800
that and I win again and lets just see whether we
get the dealer to win so click on

130
00:12:27.800 --> 00:12:29.260
dealer

131
00:12:29.260 --> 00:12:33.459
the dealer is having a bad run their new
game

132
00:12:33.459 --> 00:12:39.350
dealer again we got a draw this time so I talked
about that in the previous video wanting

133
00:12:39.350 --> 00:12:44.579
to get it draw so we got that work new game
I'm going to click on dealer again and

134
00:12:44.579 --> 00:12:49.260
lets see if we can get the dealer to win the dealer has a bad run with cards new game I'm

135
00:12:49.260 --> 00:12:54.899
going to click on dealer again and finally we get
the dealer to win so that's working well

136
00:12:54.899 --> 00:12:58.470
but we are gonna have a problem with this
and if we keep playing you should

137
00:12:58.470 --> 00:13:02.880
eventually get an error so I will see if I can do a few more
games and you think what I'm doing this what

138
00:13:02.880 --> 00:13:12.029
that error will be It might take a few more games for us to see it their we go we got it to actually crash so why

139
00:13:12.029 --> 00:13:17.130
is it crashed well the reason it crashed is that we ran out of cards their is no

140
00:13:17.130 --> 00:13:22.060
more cards remember we have we created the
deck of cards initially and we're not

141
00:13:22.060 --> 00:13:26.770
refreshing those and we're not you know
once we reach the end the deck we are not

142
00:13:26.770 --> 00:13:30.480
reinitializing that again and that is why it crashed now theirs

143
00:13:30.480 --> 00:13:34.970
many ways to solve this but the obvious
one would be to create a new deck

144
00:13:34.970 --> 00:13:41.180
list every time a new game has started by
just copying the two lines and

145
00:13:41.180 --> 00:13:48.839
in other words if I just shut this down so the two
lines and actually that turn out to be in the

146
00:13:48.839 --> 00:13:53.740
wrong place so the shuttle should
bee in strait after the deck when we

147
00:13:53.740 --> 00:13:57.100
created it for the first time so what that
actually meant was that we didn't

148
00:13:57.100 --> 00:14:02.410
execute the very first time the game is
played the shuffling of the decks so that was

149
00:14:02.410 --> 00:14:06.730
my mistake putting that in the wrong place
but what we could do the obvious approach

150
00:14:06.730 --> 00:14:12.699
would be to every time we create a new
game we basically execute these two

151
00:14:12.699 --> 00:14:16.529
lines of code create a new deck of cards and shuffle them so that each game

152
00:14:16.529 --> 00:14:22.500
literally like a standard game of blackjack with a new deck so that would be one way we can

153
00:14:22.500 --> 00:14:26.940
actually put that code in the new_game function but we're gonna take

154
00:14:26.940 --> 00:14:27.910
a slightly different approach here

155
00:14:27.910 --> 00:14:32.220
so what we gonna do is every time a new
card is dealt it is going to be put back

156
00:14:32.220 --> 00:14:36.130
at the bottom of the deck in other words
you just reusing the same deck

157
00:14:36.130 --> 00:14:40.520
continually so in Python terms the object is going to be appended back to the list so

158
00:14:40.520 --> 00:14:49.700
we want to do that in the deal_card frame and come back and have a look and you can see on line

159
00:14:49.700 --> 00:14:57.980
35 were actually popping that so what we now need to do
is before we display it....

160
00:14:57.980 --> 00:15:06.160
...so we added it back
again so.....

161
00:15:06.160 --> 00:15:10.930
.....so that should be all

162
00:15:10.930 --> 00:15:15.510
we need to do so this is actually
more realistic because it's like a real

163
00:15:15.510 --> 00:15:19.070
game and that's because when normally play a game of blackjack you don't

164
00:15:19.070 --> 00:15:22.960
start with the a brand new deck for every
single game do you just sort of just

165
00:15:22.960 --> 00:15:27.360
keep using the same deck and that is what we
are doing here essentially now there's many

166
00:15:27.360 --> 00:15:32.930
other improvements you could make to the
game if a new deck is not created for each new game

167
00:15:32.930 --> 00:15:37.390
and the game could have an option to
shuffle and let's add that as well so you can

168
00:15:37.390 --> 00:15:42.440
randomly click on a button and have it do a
shuttle for us to do that we can come down

169
00:15:42.440 --> 00:15:45.980
to the end where we actually added the new game button

170
00:15:45.980 --> 00:15:54.720
we're going to add a shuffle button so....

171
00:15:54.720 --> 00:16:01.520
....

172
00:16:05.150 --> 00:16:11.820
....

173
00:16:11.820 --> 00:16:22.830
...and we now need

174
00:16:22.830 --> 00:16:26.630
to write this function and the functions
is just going to shuffle so what I'm going to do there is

175
00:16:26.630 --> 00:16:31.270
take that line out as well and call this
function so....

176
00:16:32.920 --> 00:16:36.000
even thought we haven't written it yet we're gonna go ahead
ad write that now so gonna come up to

177
00:16:36.000 --> 00:16:47.280
the last method up here and......

178
00:16:47.280 --> 00:16:53.170
...and that should stopped those errors from showing up
now we are calling the shuttle function

179
00:16:53.170 --> 00:16:58.230
and the command shuffle is now working alright
so let's run that and just make sure

180
00:16:58.230 --> 00:17:01.230
that it is working

181
00:17:02.810 --> 00:17:05.830
ok we now got a shuffle button so just click on shuffle

182
00:17:07.670 --> 00:17:11.600
we are not getting any indication that's working but it's
also not crashing which is good so let's

183
00:17:11.600 --> 00:17:17.200
have the dealer win but the dealer lost and that's probably

184
00:17:17.200 --> 00:17:19.990
something you can also look at changing
you notice what happened there is the

185
00:17:19.990 --> 00:17:25.200
dealer actually had 15 but I continue to
draw another card and that's because our

186
00:17:25.200 --> 00:17:30.740
code had the logic that while the score
was 17 or less well less than 17 its going

187
00:17:30.740 --> 00:17:34.240
to try and draw another card so  what it should
probably be doing is each time its drawing a

188
00:17:34.240 --> 00:17:37.630
card its also checking to see whether it's
one or not that will be another enhancement you

189
00:17:37.630 --> 00:17:48.260
can look at making to the game click on new game and click on dealer again 19 so the dealer won and click on shuffle on obviously I click on new game

190
00:17:48.260 --> 00:17:53.450
that's good that's all working nicely and perhaps one other final thing you could do is you

191
00:17:53.450 --> 00:17:58.750
could add a score how many games each
player's won and display the tally at the

192
00:17:58.750 --> 00:18:03.240
top of the screen so have a go at modifying the game or to add that functionality that

193
00:18:03.240 --> 00:18:08.140
will be a nice enhancement you can make and perhaps let us
know how you went about doing it and

194
00:18:08.140 --> 00:18:09.920
maybe even show us the code

195
00:18:09.920 --> 00:18:14.180
and also perhaps look at some other features
that feature that I just mentioned

196
00:18:14.180 --> 00:18:17.280
there with the dealer when its going
to draw a new cards it's already

197
00:18:17.280 --> 00:18:21.060
won it shouldn't be drawing another card as you saw do that because ultimately lost

198
00:18:21.060 --> 00:18:26.720
because it didn't check the status to see whether it won
and I'm gonna finish the video here

199
00:18:26.720 --> 00:18:30.320
now because its getting very long but their is one last
final mini challenge and that's what

200
00:18:30.320 --> 00:18:34.970
would be how would you change the
program to play the game with several

201
00:18:34.970 --> 00:18:38.450
packs of cards in other words just assuming your adding 2 or 3

202
00:18:38.450 --> 00:18:42.470
packs of cards and you got one deck that
contains two or three packs how would

203
00:18:42.470 --> 00:18:47.460
you actually do that so if you can figure
that out right now and pause the video and

204
00:18:47.460 --> 00:18:50.470
I'll come back to me when you come back
I'll show you quickly how to do that

205
00:18:50.470 --> 00:18:53.470
so pause the video now

206
00:18:54.190 --> 00:18:55.180
...ok so the

207
00:18:55.180 --> 00:19:01.060
solution to that the moment you can see
here on line 166 deck = list cards

208
00:19:01.060 --> 00:19:10.220
that's one deck of cards so we could simply
just put.....

209
00:19:10.220 --> 00:19:15.320
and effectively you've got three packs of
cards now that are being put into our

210
00:19:15.320 --> 00:19:16.590
overall deck

211
00:19:16.590 --> 00:19:19.720
and we're still calling the shuffle which
will go through quite happily shuffle

212
00:19:19.720 --> 00:19:26.980
that entire deck which now contains the
three packs as I mentioned and looking at that the game

213
00:19:26.980 --> 00:19:30.530
functions like it would before so
that's it I'm gonna finish the video

214
00:19:30.530 --> 00:19:36.540
here and we'll move on now to more in
the way of modules I'm gonna be talking about

215
00:19:36.540 --> 00:19:40.370
using your program itself as a module so
see you in the next video