WEBVTT

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so after working through the last set
of videos we've now got a working black

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game that we can actually
whatever we want to either from the IDEA

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or ultimately from the command line as well
the one thing we can't do is include the

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blackjack module in another program

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well actually we can but the results
probably not going to be what we wanted

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so to see this what I'm going to do  I'm still in my
blackjack project and what

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I'm going to do is create another
py file so I'm going to do a new Python file

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and will call this one import_test.py we are going to start on an import so....

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....and that's the name

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of the blackjack.py file there in the
left hand side project section of the

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IntelliJ and lets try also doing a print need it to actually have at least

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one line of code in their so.... and don't worry

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about the __name yet it's just
something to print out but it's also

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something that we are going to discuss
shortly so we run the program actually I need to

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right click first and make sure I'm running import_test and not running blackjack

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because if I have click that that will have run
blackjack which is not what we're

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trying to do because we are trying to run this
import_test.py so going to

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click on that run import test and you can see
that our blackjack game has actually

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started automatically but also note that
our print statements not executed its only

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executed when we actually closed down the
window you can see the it come up

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__name_ so
this is probably not what we wanted to

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happen when we just importing the blackjack module and it's probably not what

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you expect it either you would think
that it would just the import would only

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input the code and not actually executed
and start the code is certainly in other

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parts of the course that we've used the
imports statement it hasn't actually

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executed the code its got it ready then we've
had to actually type in some code to

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get it to work so clearly
something different is happening with our

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blackjack code so I'm gonna discuss why that
happens and what you can do about it so

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that you can create your own modules from
your programs and successfully reuse your

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functions and classes in other programs

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now you may think that all of this is
not really relevant to our blackjack

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game program but in fact it actually is
its quite reasonable to include blackjack

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for example in a suite of
games you know a compendium games if you like so

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the main program with an import each of
the individual games and provided a menu

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for the player to select a game to play so
obviously in order to do that we need to

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be you know a facility to import the
Blackjack module without it immediately

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running so the techniques quite simple
and once I've discuss it will be

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writing over future programs along these
lines so that the functions can be made

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available to other programs if we want
this is also essential when building up

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class libraries in object oriented
programming so it's useful to understand

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that before we move into object-oriented
programming in the next section so when

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you import a Python module its codes
loaded into memory and then executed

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there is a bit more that goes on sorting
out namespaces and other things but

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importantly bit here is the code is
executed and that's why our blackjack

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game ran when we imported its module and
you can find a complete description of

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the import process in the Python
language reference and I'm just gonna bring up this link on the

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screen because it can be useful thing for
you to actually check out their is the link on

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the screen they're so you can go to the link
and as always its in the Resources section of

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the video so what we really want
to do with the blackjack module is only

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execute the code if the module is run as a
script which is what the IntelliJ

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product this is both IDEA and Pycharm which is their Python

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specific IDE which is what they
do if you choose to run the module in also

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what Idle does when you run a file
so in the command line you can run your

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Python program with something along
these lines if I just got back to the IntelliJ so

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this won't work but if
you're running it on the command line you do

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something like that.....

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...so that's how
you actually kick it off automatically

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and as I mentioned

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IntelliJ IDEA and Pycharm do something
similar automatically when you choose to

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run the modules as you seen numerous times
throughout this course so I'm just gonna delete that

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so in all of these cases we want the
code to be executed and the main window

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looped to start so that the game can be
played so that's where we're actually

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running it when we are choosing to run it however
in this case where we got an import statement

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on line 1 we don't want that to
happen we don't want to automatically

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start as you saw started we actually just
only want it to run if we actually

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specifically are telling the computer to run
it so I mentioned that importing a module

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sorts and name spaces as well as
executing the code and one of the

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things that happens is that an attribute of
the module called __

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name__ you can see
on line three I'm printing it out now is set to be

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the name of the module so that is the
file name without path or extension so

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when a Python modules executed a script
though the name attribute is set to

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__main__ and you can
see that was set there when we actually

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printed this out over here in our output window and we can see this by printing an attribute before any of our

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code runs so what we gonna do is switch
back over to the blackjack py file

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...will go to a shuffle method just after
shuffle the last of the methods and just

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before the first code that is
executed on line 117 so lets come up here and

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we'll type...so I've now put that in the code

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so we then run this so we actually running the
blackjack game again just to confirm so run

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it we should see the output on the screen
and their is __main and obviously

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the game itself is actually running as
well so that's good

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however we go back to import_test.py if we actually run that

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now you can see we get something different
altogether we get blackjack showing here

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this is before the app is run and obviously
once we close it down the we also get the main

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showing as well so therefore as a result
of that preventing the code from being

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executed when a module is imported is very easy we just have

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to check the value of the name attribute
and only execute any execute the code if

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it has a value in this case a second
case __main__ so what we can do

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is go back to our blackjack.py and make a
change we are going to replace the print statement

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that we just added there on line 118

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so close this down and we're going to change it and
instead of printing we gonna put....

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...and in case the number is also obviously

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important here so make sure you get those right
so we are doing a test here to see that we're

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actually in the right scope so we do that
test to see whether name is equal to

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main and if that's the case with are going to
indent this codes so select all this

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code right down and press tab that
indented all that code now so that code

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is only executed if that's the case if
__name variable__

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is equal to __main__

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ok so that's that and fix that up to keep IntelliJ happy
so now if we come back and we are in

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import_test go back

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or I could execute it their but if we run it now

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we just get main showing up at but if we tab over
you notice that the blackjack game isn't now

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starting so that's great it's now
working correctly however we then go back

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to blackjack.py itself and actually
run it from within their we find the game is running

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and that's because we specifically
said we want to run the game as opposed

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to importing it so again the big
distinction there is we're running this

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file so we're running this file directly
we are actually telling the IDE IntelliJ

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IDEA to execute the code it's being
executed just fins and so therefore the

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code on line 118 ends up being true
because we are running in main

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coming over to import where we're not
executing something we are only importing it

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and when we got to run that we are only getting the print out on line three and that is because this test

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here on line 118 failed
because we weren't running in it main because we

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are only importing it so that's great so now we can actually import our code

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and not actually execute the code so
that's actually what we wanted but

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unfortunately things aren't quite that
simple and because now the blackjack

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code is executed we got no way to run
the game once we imported it so we

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could try something like.....you could try doing that and run it but that

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gives an error and of course the error is
to do with initialization because when we're

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running it from there when we importing it
rather all this code from 120 through 178

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has not now not being executed
consequently all these variables haven't

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been defined so we haven't actually got
a dealer card frame etc so that is why its

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crashing so that's actually quite easy to fix all we really have to do is decide which

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bits of the blackjack module should be
executed when a module is imported and

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moved the test for the __name_ to allow
that to happen so your challenge here

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now is to change the blackjack module
to include a function called play that's a

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responsible ultimately for allowing or

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running the code that starts the game so
you want to test that the play function can be

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used to start the game when the module
is imported so again change the

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blackjack module itself to include a
function called play and that

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function should be responsible for
actually running the code that starts

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the game then test the play function can
be used to start the game when the

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module is imported that your way of
knowing that things are working as they

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should so go away and city and see if you can figure that
out and when you ready to come back

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you can come back and check our
solutions so pause the video now....

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...ok so hopefully you manage to figure
out a solution for that so again what

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we're trying to do is create a function
that's responsible for actually running

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the code that starts the game so again the
distinction here is it's running the

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code that starts the game it's not the
initialization

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go back to blackjack.py the
initialization we still want to actually

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execute that at the time it gets imported
but we only want the code that actually

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runs the game to be executed when we
specifically called the play function so how do

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we do that well we create a new function
we are gonna call it play....and the code is

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basically gonna be the code that was in
here I'm gonna take those three or 4 lines of

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code their

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cut those and put those into the play method

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but then the other line of code we want is
the code that starts officially

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and that's this code here so we are going to take that out and paste it in

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there as well and that is obviously the main loop
that actually runs the game itself so

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consequently we've now got a play function
that's really only going to be executed

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when we're ready to actually run the game
so we now need to come back here and

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remove the indent....then this

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bit of code here we are gonna change this now so that name is equal to main if

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that's the case we just gonna call the
play method...and that should also be

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that the indent removes...so now lets try running this and

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see if it actually works and what
we need to do obviously we need to move

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this code down here now to be executed
right as the last line we need the rest of

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the code to be executed first
and right at the end

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after this initialization come down
here

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...we put the code their and we can remove the new game as well at that point so at this point now it should actually work

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so if we now run this running the blackjack file itself

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...and click on player to get another card now we are busted click on new and we got a problem here we got no dealer card and I think I know what that is...

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so close this down so what we've done is we've
added this play function and that's great

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its working the first time

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we play but if we come up here and have a look at
the function we got this code this

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deal_player and the code
that creates or redraws the cards

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initially and that needs to be put in
also to our new game method and the new

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game method of courses is now executed every time
the new buttons is click just to start a new game

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because otherwise that you know when a new game button
is clicked the code is executed the

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frames destroyed but there were not
actually creating a new set of cards

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for the player and dealers properties so if I click on their and paste that code into be

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executed so now if we run this you should
find it works check here and I'll actually

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hit we got 21 thats good click on dealer dealer
losses so I win click on new game and we now got it

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working correctly because we're getting
a new card new hand each time and hit again

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dealer got 21  dealer wins and that's working the score are all working nicely so

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that's it that's good so now let's go
back and check to see whether import

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_test.py is working and if you
remember we had on new_game

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and that's not going to work now because we
created this function now to do it

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specifically so its going to be play so if we do blackjack.play it should automatically start are game and if

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we come over here and have a look it seems to be
working I'll click on player

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and I'll let the dealer go the dealer wins new game

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hit dealer dealer wins a game 21 and try it one more time

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and player wins so it's working fine and
just as a final check if I comment that line

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out and add a exta line to keep Python happy and
run it again we should find the game

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now doesn't start automatically click on
and run import test and it correctly doesn't start

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because we haven't invoke the play method we will leave that their anyway so that's good that's actually

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working now and just as final thing we
could do if we wanted to we could do.....

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...and if I do that and run it and obviously

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that's not gonna be invoked now until we closed down this so close down that

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you can see line of code has been executed
with our list of cards so now the

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same pack of cards could be used for
many different types of games now if we wanted to

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and that's really another good reason
for copying the cards lists to create

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deck in the blackjack game that's why we
actually did the cards list is not

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modified once it's been created so it
can be safely reused so this turned out

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to not be the easiest program to import and that is because it uses a

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graphical user interface that requires a lot
of initialization now there's a lot of

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code that has to execute when the module
is imported and the modules also used

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many global variables for the same
reason so you can get rid of the global

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variables using classes and we'll be
covering that in the next section but

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before we get into object-oriented
programming there's a few more aspects

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of functions and namespaces that we really want to cover for you understand to finish of

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this section so just one last thing
that I think we can add to this before

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we actually finish of the blackjack game
and it relates to this code here that I duplicated

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so its probably not a good idea we
need to execute this code for dealing

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with the player every time dealing new
card for the player one for the dealers and

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another for the player each time we are invoking a new game and likewise when we are gonna play

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for the first time we need to do that as
well and we don't want to actually put

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all this code and only execute the new
game method the first time when we play because

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we basically deleting the frame and
re-creating it again so what I'm going to do

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is just create one final method and put
this code that is going be executed in two

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places in there so that we're not
duplicating our code because it's always a

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good idea to fix the issue if your duplicating code so come up here

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and I'm going to create a new method so call it....

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...and this is going to be our initial
dealing of the cards when a new game

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start so grab this code here and I'm gonna
place it in init deal then under the new

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game here  and I'm gonna
go....

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....

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.....

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....what's
happening now is that we haven't got any

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code duplicated and if by chance we
decided to change the code to d

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that initial deal you know maybe we did
something else or showed it or added another

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labeled or did something we can still
modified it one place namely the

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initial_deal and it's still gonna
work so let's check that does work

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I'm actually running import test because its selected
so so that should have started and that's

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because we got the code now to play
and just make sure that the game does

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work

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we got 20's so I'm going to click on deal and i win that click on new game and we got cards looks like its going to work

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i'm gonna play 19 dealer 18 and I win again i'm on a roll one
more

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15 actually will just try another one and will just see whether the ace does work I think we saw that working but lets just

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check that and will do one more and notice how
that's work we've got 456789 10 and 11 is 21

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but lets actually click another
card even though you wouldn't ordinarily do

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that just to make sure the ace going back
to one does work so click on that

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and you can see that does work 6 3 9 3 is 12
4 is 16 1 is 17 so we definitely got the ace

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working on either 11 or 1 depending
on the hands so that's good and click on deal and the

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dealer wins this time so that's working okay and
lets do just one final check before we

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finish this going to blackjack it will just
run from here

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to confirm that it still works that way and that is still working so click
on dealer and player wins alright so

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I'm going to finish this video here now
and we'll continue on in the next video