Friday 3rd November 1995
coding Lecture 5
----------------

The doors part so you can enter the Auditorium.
Carlin Auditorium <StarFleet Academy>
You are catapulted back into the late 20th century as you step through 
the double doors and into the dimness of the back of the Auditorium. As 
your eyes become accustomed to the lacklight, you begin to appreciate the 
beauty of this unique Terran decor. More than 200 seats, divided by two 
wide aisles spread over the main floor. An overhanging balcony provides 
additional seating. Three luxurious private boxes, obviously for visiting 
dignitaries, are visible on either side of the expansive walls. Thick red 
and gold carpeting covers the floor. All seating is upholstered in plush 
red velvet, a common covering for the era that is being depicted here. 
Two large gold pillars stand like silent sentinels on either side of a 
stage that spans the full width of the room. The only hint that you are 
still in your own time are the three familiar flags; Starfleet, 
Federation, and that of Starfleet Academy that stand proudly on the left 
side of the stage. 
Contents:
Widdy's PADD
Widdy
Final Test Section
Obvious exits:
Out <O>  
Widdy's PADD says in a computer voice "Mark_Farrell is a Merchant Pilot"
Widdy says "hello sir"
Mark_Farrell smiles.
You say "Evening Cadet."
You say "Are you here for the coding lecture?"
Widdy says "yes sir, still reading your logs you sent me this week"
[Academy] Mark_Farrell: <TA><FMO> Well, for anyone interested, this 
week's coding lecture is starting now in the Carlin Auditorium.
[Academy] Borric: <///><Nav/Helm> what is it going to be on?
Widdy tries to sit the the chair but his wings get in the way
[Academy] Mark_Farrell: <TA><FMO> Well, anything that you are interested 
in and need questions answering about. I have been working through a 
coding example, but the regular attendees are absent today, so I'm making 
it a general session.
Salek has arrived.
Salek enters from the Quad.
Widdy's PADD says in a computer voice "Salek is a Cadet"
[Academy] T'korik: <O*/MCS/TA/CAP/SFSBS/TST> What's the skill level?
Mark_Farrell puts down his notes and takes the example device off the 
null gravity sled.
Salek says "Indeed."
Dropped.
Salek says "Wow."
[Academy] Mark_Farrell smiles. That all depends on who attends.
Widdy says "how is wip going sir, just been reading about it"
[Academy] D'henriao has left this channel.
[Academy] Borric: <///><Nav/Helm> well i haven't got the foggiest idea 
how to code.
Tai_Mylen has arrived.
Tai_Mylen enters from the Quad.
Widdy's PADD says in a computer voice "Tai_Mylen is a Lieutenant"
[Academy] Borric: <///><Nav/Helm> well at least not in this language anyway.
Tai_Mylen nods to all
You say "The Work in Progress - a poker game - is coming towards the 
stage of adding the player interface."
You say "The only outstanding operational issues are discarding cards, 
and calculating the winner."
Salek says "Hm."
Widdy quickly reads the back logs to get up to speed
Mark_Farrell replicates himself a jug of water and stands it on the podium.
[Academy] Mark_Farrell: <TA><FMO> If you want to +mail me your email 
address, I have 4 lecture logs you might wish to read through.
Carlin Auditorium <StarFleet Academy>
You are catapulted back into the late 20th century as you step through 
the double doors and into the dimness of the back of the Auditorium. As 
your eyes become accustomed to the lacklight, you begin to appreciate the 
beauty of this unique Terran decor. More than 200 seats, divided by two 
wide aisles spread over the main floor. An overhanging balcony provides 
additional seating. Three luxurious private boxes, obviously for visiting 
dignitaries, are visible on either side of the expansive walls. Thick red 
and gold carpeting covers the floor. All seating is upholstered in plush 
red velvet, a common covering for the era that is being depicted here. 
Two large gold pillars stand like silent sentinels on either side of a 
stage that spans the full width of the room. The only hint that you are 
still in your own time are the three familiar flags; Starfleet, 
Federation, and that of Starfleet Academy that stand proudly on the left 
side of the stage. 
Contents:
Tai_Mylen
WiP(#126vIq)
Salek
Widdy's PADD
Widdy
Final Test Section
Obvious exits:
Out <O>  
[Academy] Borric: <///><Nav/Helm> for what? coding?
[Academy] T'korik: <O*/MCS/TA/CAP/SFSBS/TST> What did you cover?
Tai_Mylen says "Shall I start?"
Widdy I'm M3/C Widdy, I've got basic coding abilities (as you can see 
with my PADD).
Tai_Mylen says "I guess not :)"
Widdy says "M3/C Widdy, I've got basic coding abilities (as you can see 
with my PADD)."
Tai_Mylen sits quietly and waits
Mark_Farrell sighs as he lags.
Salek says "Well, I'm Mid 2/C, I can code fairly well... I'm working on a 
bartender / tables system for Kennedy Station's observation lounge.."
Tai_Mylen says "I'm a Lt., and Chief of Nav on the USS Constitution, my 
coding ability is simple-moderate.... what I'm interested in learning, is 
how to store data in objects etc"
[Academy] Mark_Farrell: <TA><FMO> A fair number of things from the basic 
definitions of object/register/command/function through to the current 
work in progress - a poker table. A prime focus has been on being 
efficient, and thinking through different ways to acomplish certain tasks.
Mark_Farrell nods.
You say "Alright. Specific topics that you want covered today?"
Tai_Mylen says "Well... I'd like to know how to store data in an 
object... ie, like compin.... and also, something kinda specific..."
You say "Okay. So basically things like arrays, Tai?"
Tai_Mylen says "Theres an intercome on the birdge of COnnie.... its hooks 
eng to the bridge... it can be set audio, visual or off.... I wanna know 
how to make an object have 3 modes..."
Tai_Mylen says "Yes... basically... other than MUSE coding, I dont do 
very much coding"
Mark_Farrell nods.
You say "Anyone else have some suggestions?"
Salek Shakes his head.
Gemmell has arrived.
Gemmell enters from the Quad.
Widdy's PADD says in a computer voice "Gemmell is a Ensign"
Norm has arrived.
Norm enters from the Quad.
Widdy's PADD says in a computer voice "Norm is a Cadet"
Tai_Mylen nods to Gemmell
Gemmell slinks in the back
Gemmell nods
Norm quitly sits down.
You say "Alright, so basically todays lecture is going to cover basic 
data storage and retrieval."
Norm whispers "is it just beginning?"
You say "I'm going to tie this into a discussion on the player interface 
to the poker table."
You whisper-posed Norm with "Mark_Farrell nods.".
You say "So, we basically have to have 1. A commanding interface, and 2. 
The code to do the work."
Salek has disconnected.
Salek has connected.
You say "In earlier lectures I've covered a good portion of the 2. Logs 
are available on request."
Gemmell slinks out the back again
Gemmell leaves the Auditorium.
Gemmell has left.
You say "In essense, what we have arrived at is a single register to hold 
the entire list of 52 cards, and these are logically broken down for each 
player."
You say "An alternative to this would have been to store each player's 
cards in an individual register."
Widdy nods
You say "For example, wa for player 1, wb for player 2, etc."
Norm nods
You say "Instead, we use cards 1 to 10 for player 1, 11 to 20 for player 
2, and so on, upto a mximum of 5 players."
You say "We use 10 cards to handle discarding cards easily."
You say "At one time, each player can only see 5 of them. The other 5 
being the replacements for discards."
You say "Now, to come to array handling - we need some way to turn the 
list of cards into a display for the player."
Norm says "do you mean converting it to 3 of Spades, etc.?"
You say "Partially. I covered turning the internal card representation (a 
number) into a user-friendly string in lecture 2."
You say "I am driving at the interaction between a player, the cards for 
that player, and doing useful operations with that data."
You say "The first thing we need to do is to have a list of people who 
are playing a particular hand."
You say "We will need this to be able to determine which cards are 
visible for which player."
Norm will be leaving, and will request for the logs. Thanks. Bye!
Mark_Farrell looks around. "Are there any questions so far? I should have 
said to stop me as soon as I say something that you do not follow."
Widdy is still with you
Norm leaves the Auditorium.
Norm has left.
*Mark_Farrell* Time : Fri Nov 3 18:37:34 1995, Stardate : 95838.7 18:37:34
Mark_Farrell smiles. "Okay."
You say "So, other issues we should have rolling around our minds while 
we think of ways to perform this task include:"
You say "Preventing a player from joining the game twice."
You say "Preventing more than 5 players joining in a hand."
You say "In essense we need something like : IF P requests to join game, 
AND P is not already playing, AND there are less than 5 people in the 
hand, AND the hand hasn't started, then add P to the list of players."
Widdy nods
You say "Right - so this brings us to the second thing we need for the 
game - a concept of 'what the game is doing' - ie, waiting for new 
players, shuffling cards, betting, discarding, who's turn it is, who's won."
You say "Initially, I'm going to ignore that, and assume that the players 
are clever enough to do the right things at the right time."
WiP(#126vIq)
Work In Progress for Coding Workshop. A poker table.
Owner: Mark_Farrell  Credits: 1
Status: Thing    Org: Federation <Int Trade and Comm>(#7479)
Type: Thing      Flags: visible inherit quiet
Vd:$new deck:@xa me=[iter2(lnum(13),{[add(##,16)]})] 
[iter2(lnum(13),{[add(##,32)]})] [iter2(lnum(13),{[add(##,64)]})] 
[iter2(lnum(13),{[add(##,128)]})]
Xa:17 18 19 20 21 22 23 24 25 26 27 28 29 33 34 35 36 37 38 39 40 41 42 
43 44 45 65 66 67 68 69 70 71 72 73 74 75 76 77 129 130 131 132 133 134 
135 136 137 138 139 140 141
Lock:Mark_Farrell(#16055PDeoqFc)
Vb:16 Clubs 32 Diamonds 64 Hearts 128 Spades
Va:$test *:@emit > %N types %0. The value returned is 'The 
[extract(v(vc),band(v(0),15),1)] of [lookin(v(vb),band(v(0),240),1)]'.
Vc:Ace Two Three Four Five Six Seven Eight Nine Ten Jack Queen King Joker
Race:Mechanoid
Ulock:Mark_Farrell(#16055PDeoqFc)
Xf:21 19 72 18 39 130 74 133 24 132 43 137 17 66 134 38 41 67 73 20 45 
136 27 42 37 135 141:: 129 77 22 23 34 140 75 35 76 28 29 71 70 36 139: 
33 65 44 26 138 40 69 68 131 25
Xg:21 19 72 18 39 130 74 133 24 132 43 137 17 66 134 38 41 67 73 20 45 
136 27 42 37 135 141 129 77 22 23 34 140 75 35 76 28 29 71 70 36 139 33 
65 44 26 138 40 69 68 131 25
Ve:$shuffle:new deck;@xb me=[shuffle(get(me/xa),13)];@xc 
me=[shuffle(de_(first(get(me/xb))),13)];@xd 
me=[shuffle(de_(first(get(me/xc))),13)];@xe 
me=[shuffle(de_(first(get(me/xd))),13)];@xf me=[rest(get(me/xb))] 
[rest(get(me/xc))] [rest(get(me/xd))] [rest(get(me/xe))];@xg 
me=[edit(get(me/xe),:,spc(1))]
Vf:$deal card:@xf me=[first(v(xe))];@xe me=[rest(v(xe))]
Home: Ready Room <USS Figment>
Location: Carlin Auditorium <StarFleet Academy>
Vg:
You say "So, turning the method above into some form of code
You say "Examine wip/vg"
Tai_Mylen smiles
You say "Initially we are going to use @switch for checing the number of 
players, and so on."
You say "Let us pick register WA to hold the list of players already in 
the game."
Widdy writes this down
yoda has arrived.
yoda enters from the Quad.
Widdy's PADD says in a computer voice "yoda is a Cadet"
Mark_Farrell takes it in steps. [eq(words(v(wa)),5)] is our check for 
having 5 players already.
Mark_Farrell reminds you of earlier lectures. "Take it from the inside 
and work out. v(wa) returns the contents of register wa, and words() 
returns the number of words in the register. So, we have the number of 
words in wa.
Salek says "Sir, excuse me, but I need to leave."
Tai_Mylen says "What is the eq part?"
Mark_Farrell nods.
Salek leaves the Auditorium.
Salek has left.
You say "eq() compares to values, and returns 1 if they are the same."
Tai_Mylen nods
You say "So, basically, we have: IF words in wa is 5, return a 1 ELSE 
return a 0"
Widdy writes it down
Vg:$join game:@switch [eq(words(v(wa)),5)][truth(member(v(wa),v(#)))]=.....
You say "Okay, lets take the next bit : [truth(member(v(wa),v(#)))]"
You say "Someone want to take a stab at how this operates"
Mark_Farrell reminds you all the 'help <function-name> function' works 
for just about every function now if you see something you are not sure 
about.
Tai_Mylen says "member retur checks to see if the persons na,me is in the 
wa register..."
You say "Okay... we have v(wa) - as before returning the contents of WA. 
and we also have v(#)."
Mark_Farrell nods.
You say "Thats right, Tai."
Tai_Mylen says "Truth checks to see if they are... if both argumetns 
mathc, truth returns 1"
Tai_Mylen says "Wait... I'm getting confused now...."
Tai_Mylen scrtaches his head
You say "Nearly."
You say "Let me explain."
Tai_Mylen nods and listens
You say "member(v(wa),v(#)) looks to see if v(#) - the players database 
number is in the list in WA."
Saving TrekMUSE DataBase. Response will be slow for a few minutes.
You say "Now, the member function returns 0 if there isn't a match, or 
the position in WA that was matched."
You say "For example, member(a b c d e,c) returns 3"
Widdy nods
You say "For example, member(a b c d e,Z) returns 0"
Tai_Mylen nods
You say "truth() returns 1 if the number if non-zero."
You say "So, now we can consider the whole of the first part of the @switch."
You say "@switch [eq(words(v(wa)),5)][truth(member(v(wa),v(#)))]=....."
Tai_Mylen whispers "SOrry... time for my meeting.. got to run.. how do I 
go about getting"
You whisper "+mail me an email address." to Tai_Mylen.
Tai_Mylen whispers "a log?"
Tai_Mylen whispers "Ok.. thatnks :)"
Tai_Mylen quietly slinks out
Tai_Mylen leaves the Auditorium.
Tai_Mylen has left.
You say "Now, this can return 4 possible cases, as each of the two things 
we switch on can return 0 or 1."
Widdy raises his hand
Mark_Farrell nods "Widdy"
You sense you have new mail from Tai_Mylen.
Widdy says "Is there a text file on all of the commands?"
You say "Help commands will show you the list"
You say "You can log this offline, or screen dump it, or similar for an 
uptodate list of commands available here."
You say "Was there anything else, WiddY?"
Widdy says "thanks, back to the problem, isen't there going to be 5 
possibles cases since there is going to be 5 players?"
Mark_Farrell nods. "However, to start with, we are just going to look 
after the failure cases. - already 5 players, or already playing.
Widdy says "ok"
You say "THe truth() command means we see '1' if the player is already 
playing, and a '0' if they are not."
Vg:$join game:@switch [eq(words(v(wa)),5)][truth(member(v(wa),v(#)))]=.....
Widdy says "yes, up to speed now sir."
You say "Okay, so we get: 00 if there are less than 5 playing, and the 
player is not already playing."
You say "01 if there are less than 5 and the player is playing already."
You say "10 for 5 players, not-already playing"
You say "11 for 5 players and already playing."
You say "So, only 1 of the four cases is 'legal'"
Widdy understands
You say "Now, we hope that the 'legal' case will be the one that is used 
most often, so we will look for it first."
You say "@switch [=00,{....},......."
*Mark_Farrell* @switch [][]=00,{....},.......
You say "The commands inside the {} will be those executed for case 00"
Widdy nods
You say "In a similar manner, we can check for 01, 10 and 11 and give out 
appropriate information."
*Mark_Farrell* @switch [][]=00,{....},01,{....},10,{....},11,{....}
You say "Or we could just assign a default case to tell the user that 
that isn't allowed."
*Mark_Farrell* @switch [][]=00,{....},{default}
Widdy says "but in that case the player won't know why the player can't play"
Mark_Farrell nods.
You say "That's right."
You say "We could also compromise, and tell the player either they are 
already playing, or that there are 5 players already."
You say "We would use wildcards for that."
Widdy nods
*Mark_Farrell* @switch [][]=00,{....},01,{....},1*,{.....}
*Mark_Farrell* Time : Fri Nov 3 19:15:59 1995, Stardate : 95838.7 19:15:59
You say "The * matches any number of characters, so it matches 10 and 11"
You say "We could also (and it may be better in this case) to use a ?, 
which only matches a single character."
You say "Okay - so, lets consider what we want to do when we are in the 
'legal' case."
Widdy says "the same can be for ?1 (or *1) for 01 and 11"
Mark_Farrell nods. "That's right"
Kyrell has arrived.
Kyrell enters from the Quad.
Widdy's PADD says in a computer voice "Kyrell is a Cadet"
Kyrell says "Huh?"
Kyrell snaps to attention
Mark_Farrell smiles. "At ease.
Kyrell says "There is a exam right now??"
You say "I am holding a coding lecture, but I'm not aware of a final 
being given right now."
Drakon has arrived.
Drakon enters from the Quad.
Kyrell says "Oh... ok...."
Widdy's PADD says in a computer voice "Drakon is a Cadet"
Mark_Farrell smiles at Drakon. "Hello there."
Drakon says "da"
Drakon says "hi there everyone"
Drakon says "who's wip?"
You say "I'm giving a coding lecture if you'd like to take a seat."
Kyrell sits down
Drakon says "oh.. MARK!!! didn't recognize ya for a sec.. how are ya"
You say "WIP is the Work-In-Progress :-)"
Drakon says "oh ya.. an example of codeing.. i have a bucket.."
Drakon says "it sings"
Kyrell says "I have a Modified Shuttlecraft"
Drakon says ""
Mark_Farrell coughs, a slight frown forming.
Drakon says "and my hoverbot talks also"
Drakon says "ahem"
Drakon morphs himself a chair and takes a seat. You notice how realistic 
it looks.
You say "Alright, so, I was just talking about the work we need to do to 
store the new player in a list."
Vg:$join game:@switch 
[eq(words(v(wa)),5)][truth(member(v(wa),v(#)))]=00,{...},
You say "If you look at wip/vg you can see the command I'm refering to."
You say "Now, there is an obvious way to add an entry to a list - and 
that is by using @wa me= <new-item>"
You say "Or @set me=WA: <new item>"
Widdy takes a look at Kyrell.
Drakon lags alot
Drakon has disconnected.
You say "Now, that works in most cases, but is not as efficient as it 
could be."
Drakon has connected.
You say "The better way to add to a list is by using @edit"
You say "Read 'help @edit'"
Kyrell has disconnected.
Drakon raises his hand
Mark_Farrell nods at Drakon. "Go ahead"
Drakon says "this wip... it does what? plays poker? :)"
You say "Eventually."
Drakon says "so id.. it isn't a weapon"
You say "It is a mixture of example code taken from my lecture series so 
far."
Mark_Farrell grins and shakes his head. "No it's not a weapon."
Drakon snaps his fingers... and curses under his breath.. :)
You say "Using @edit me/wa=$,{ #16055} will add an item to the list in WA 
in the most efficient way."
Mark_Farrell means @edit me/wa=$,{ %#}
Drakon notices... WWWWHHHHHHISSSSHHHHH!!! its way over his 400 year old 
changeling head
Drakon :)
You say "Now, this is probably a good time to recap when we can use %#, 
and when we need v(#) or [v(#)] and what the differences are."
You say "I touched briefly on this in the first lecture."
Drakon thinks. "ah"
Mark_Farrell notes this is lecture 5
Widdy notes all of this down and thinking of how to put this in his PADD
Drakon says "excuse me please."
Drakon leaves the Auditorium.
Drakon has left.
Mark_Farrell smiles.
You say "Alright - now, the basic rule for using %# or v(#) is if you are 
inside square brackets."
You say "Both %# and v(#) return the player's database number, but %# 
doesn't work inside square brackets.(normal cases anyway)"
*Mark_Farrell* My player number is %#
Widdy notes this
*Mark_Farrell* @pe me=My player number is [%#]
Drakon has arrived.
Drakon enters from the Quad.
Widdy's PADD says in a computer voice "Drakon is a Cadet"
Drakon leaves the Auditorium.
Drakon has left.
You say "However, @pe #%=My player number is %# does, because the 
predicate (%#) is outside of the brackets."
Widdy nods
You say "We could also have gone the other way, and used [v(#)] instead 
of %#"
You say "V(#) is a function, and the way we indicate that to the parser 
is to surround it with square brackets, or to have it insode another 
function."
You say "There are two cases where a function is recognized without 
square brackets though."
You say "They are: 1, as the first parameter in a command. Eg, @command 
function()=......"
You say "The other is immediately after the first equals sign, @command 
...=function()"
Widdy understands
You say "However, in both cases I would recommend that you use square 
brackets anyway, and they make the code easier to understand."
You say "The choice between using a predicate and a function is fairly 
clear cut. You should always favour the predicate as it requires less 
work for the parser. There are some cases where you can't use it."
Widdy nods
You say "The parser 'sanitizes' predicates by removing special characters 
from them, to try to prevent a malicious user from breaking you code, by 
using extra commas, semi colons etc."
You say "It does not do this for functions."
You say "Is that fairly clear, Widdy?"
Widdy says "yes sir, I'll study it better by reading it later"
Widdy says "ooc: my online time is almost up sorry."
Widdy's PADD has left.
You say "Alright. Take a look at wip/vg and ask me quickly anything you 
need explaining."
Vg:$join game:@switch 
[eq(words(v(wa)),5)][truth(member(v(wa),v(#)))]=00,{@edit me/wa=$,{ 
%#};@pe %#=You have been added to the hand as player 
[words(v(wa))].},{@pe %#=I'm sorry, you cannot join this game as you are 
either already playing, or there are 5 players already.}
Mark_Farrell has basically added the @edit, and a message to the player 
joining the game that they are accepted, and a generic failure message.
Widdy understands it
Widdy says "thank you sir, you have given me a lot to think about coding, 
I might have something better then my PADD next week (is there a next week?)"
You say "Okay, that seems a good place to stop. Do you have any 
questions? Or any comments on how I gave the lecture, the style etc?"
You say "There is always a next week - this is a regular Friday night 6pm 
til about 8pm thing."
You say "There is the FedCode, and Gadget channel in the meantime, and 
you can always page me for help."
Widdy says "it was good, the time is ok (ooc: it's now 12pm sat here)"
Mark_Farrell nods. "It's 1am Saturday here.
Mark_Farrell is in the UK.
*Mark_Farrell* THE END OF LECTURE 5 LOG
Widdy says "well got to go sir"
Mark_Farrell nods. "Take care, Widdy."
Widdy goes home.
Widdy has left.