I'm half thinking-out-loud here and soliciting thoughts on a programming lesson. If this sort of thing bugs you, feel free to ignore. --- My son is coding this flow-chart as a Q&A type application:
http://media.www.gamespy.com/articles/633/633817/img_2913464.html
So, it says, "You found something!" then asks "Is it alive?" and then branches out accordingly. I'm letting him muddle through with the idea of using his code as a platform to teaching him a better approach (or approaches).
Looking at the chart, it looks like spaghetti code, and reminds me of some of the stuff I did in BASIC. And that's sort of what he's doing within Smalltalk. I'm actually tempted to show him how it would look in BASIC using GOTOs and line numbers. It would have the advantage of being easy to see all in one glance.
But I want to, of course, show him a better approach and explain why it's better. My first thought was to make a state machine, but I don't think that'd be much better, in fact.
Then I thought of what I would do, professionally, in a similar context: The problem with the spaghetti code and even a state machine is that it's static, and adding bits and pieces tends to require everything to be massaged around the new parts. In the real world, I know that the chart's not going to be static.
I'd probably end up create a linked list of one-exit nodes and two-exit nodes.
So, that's what I'll probably show him.
The other thing I'd do, though, is put this all in an editable text file, like:
1,foundsomething,"You found something",alive 2,alive,"Is it alive?",friend,smash 2,friend,"Is it a friend?",lately,scary 1,smash,"Smash it with a stick!",shiny
But I'm wondering if this last wouldn't be too much.
Thoughts?
Hi Blake,
Welcome to the list. Before telling you what I would do I have two things to say.
First when I'm teaching people Smalltalk (and by the way I'm not a teacher, the only people that I've taught is coworkers or people that worked for me) I give a them a lot of latitude to make mistakes. I give a lot of credit to someone for making something that works. Only after they succeeded in doing something on their own do I go back and explain methods and techniques that would improve their programming, usually on a different project. So keeping that in mind it may be better to let your son solve the problem on his own and then go back and build something else using some new techniques that you can show him.
Second there are a lot of possible designs for this problem. The implementation of the design should be kept separate from the design itself. Whether or not you use a text file or how you store the data is a detail. The details come easy once you have a good design. So focus on design first.
That aside this is a fun question. (Although I really don't like the actual flow chart, killing and kids don't mix well in my mind. I know there are lots of killing video games but not that I let my child play)
The real problem is that it is difficult to gather the requirements so since this is just a conversation I thought I'd just make them up.
First I want my game to be able to add things. It should be easy to do. The things should be able to answer questions based on properties of the things. Next I want the thing to be able to follow multiple question flows. It should be easy to add properties, questions and flows to the design. I would personally like to be able to ask random questions so that I can follow random flows.
OK so this is Smalltalk so let's figure out what objects we have.
We have: Thing, Property, Question, Message, Tree.
The Thing has properties.
The Property has a question.
The Question has an answer of yes or no.
The System gives user Messages.
And we build the flow with a Tree.
The Tree routes by Questions.
If the Tree does not have a question then it routes automatically to the next Tree.
If the Tree does not have another Tree then we are done.
Ok so first thing we need to do is build properties.
Each property has a question so build a property by giving it a question. We could also add a name.
Property instanceVariableNames: 'propertyName question'
In your example there are only properties that have yes answers but there could be a property that applies on a no answer. For example:
Property -------- question -> Question -------- Question -> Is it round? answer -> no propertyName -> non round thingy
So now have your system add properties by asking you to name the property and then type in a question and its answer.
For example:
System: Enter Property Name: You: Scary System: Enter Question for Property Scary: You: Is it Scary? System: Answer to question Is it Scary?: You: yes
Now that we have properties we can build thingys
What we do is have you provide the things name and then ask you all the questions from all the properties that you added.
If you answer the question with the same answer that is stored on the property question then the property is added to the thingy.
Now you have thingys with properties. We need to build a flow.
A tree has a question or a message.
Tree instanceVariableNames: 'questionOrMessage yesOrDefaultTree noTree'
So now you build your tree by having the system ask you for a question from the list of questions added by properties or you can optionally type in a message.
If you add a message like: Boring find another thing. Then you can either add a default tree to the message or nothing indicating that you are done.
So for every question added, the system should ask you for the next question or message allowing you to specify the yes or no tree to add too. And it should verify each branch on the tree has a yes and no tree or ends in a message.
Notice there is no branching code any more. To follow a flow you start from the root tree.
Tree >> processFlow "move along the tree branches until there are no more trees, displaying the question or message and following the path based on answers" anAnswer := nil. self dispayQuestionOrMessage self treeHasQuestion ifTrue: [ "do not allow anAnswer to be set to nil" anAnswer := self getAnswer. ]. (anAnswer isNil or: [anAnswer isYes]) ifTrue: [ self yesOrDefaultTree isNil ifTrue: ["we are done" ^self] ifFalse: [^self yesOrDefaultTree processFlow] ]. ^self noTree processFlow
Ok so why did we build thingys? Well because things can now answer questions for themselves and we can build costumes on thingies and get them to run around on screen. Now we don't have to ask the user questions we can just send messages. (Like KILL! Ugh).
So to summarize my suggestion: you use a tree construct to represent branching instead of using hard coded flows. (It is not really a linked list) You build objects that represent properties that have questions and answers. You can then build things that have these properties.
Hope that helps and wasn't too complicated.
Ron Teitelbaum President / Principal Software Engineer US Medical Record Specialists www.usmedrec.com
From: Blake Sent: Saturday, February 17, 2007 7:11 PM
I'm half thinking-out-loud here and soliciting thoughts on a programming lesson. If this sort of thing bugs you, feel free to ignore.
My son is coding this flow-chart as a Q&A type application:
http://media.www.gamespy.com/articles/633/633817/img_2913464.html
So, it says, "You found something!" then asks "Is it alive?" and then branches out accordingly. I'm letting him muddle through with the idea of using his code as a platform to teaching him a better approach (or approaches).
Looking at the chart, it looks like spaghetti code, and reminds me of some of the stuff I did in BASIC. And that's sort of what he's doing within Smalltalk. I'm actually tempted to show him how it would look in BASIC using GOTOs and line numbers. It would have the advantage of being easy to see all in one glance.
But I want to, of course, show him a better approach and explain why it's better. My first thought was to make a state machine, but I don't think that'd be much better, in fact.
Then I thought of what I would do, professionally, in a similar context: The problem with the spaghetti code and even a state machine is that it's static, and adding bits and pieces tends to require everything to be massaged around the new parts. In the real world, I know that the chart's not going to be static.
I'd probably end up create a linked list of one-exit nodes and two-exit nodes.
So, that's what I'll probably show him.
The other thing I'd do, though, is put this all in an editable text file, like:
1,foundsomething,"You found something",alive 2,alive,"Is it alive?",friend,smash 2,friend,"Is it a friend?",lately,scary 1,smash,"Smash it with a stick!",shiny
But I'm wondering if this last wouldn't be too much.
Thoughts? _______________________________________________ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Hey, Ron,
Thanks for the feedback. It is a fun question.
Welcome to the list.
Heh. I've been on this list since it started and on the general list for years, but I guess I don't make much of an impression.
...it may be better to let your son solve the problem on his own and then go back and build something else using some new techniques that you can show him.
Sorry if I hadn't made that clear: That's precisely what I am doing.
Second there are a lot of possible designs for this problem. The implementation of the design should be kept separate from the design itself. Whether or not you use a text file or how you store the data is a detail. The details come easy once you have a good design. So focus on design first.
Right. I meant to draw contrast to a traditional state machine where things are fixed, and went to a specific detail.
That aside this is a fun question. (Although I really don't like the actual flow chart, killing and kids don't mix well in my mind. I know there are lots of killing video games but not that I let my child play)
Not to get sidetracked on the issue, but I introduced my son to computers and gaming at the age of...oh...15 months by having him sit on my lap and fire the weapons in Doom 2. I can't really explain in brief the extent of the positive changes this wrought. He's had an abiding love of games--including "violent" games--ever since. (I put "violent" in quotes for a lot of reasons that are also not on topic.<s>) Completely coincidentally, he's by far the most compassionate persion I've ever met. I've never met anyone so completely devoid of cruelty and so quick to help others in distress.
(Of course, results not typical, your mileage may vary. I filter out plenty of other things I think are bad for him; it's just that his list is different from other kids'.)
By the way, in case it's not obvious, this is a flow chart for the pen-and-paper RPG "Dungeons and Dragons", and is meant as a jokey simplification of that game.
System: Enter Property Name: You: Scary System: Enter Question for Property Scary: You: Is it Scary? System: Answer to question Is it Scary?: You: yes
Ah. Yes. This is "Animals", in essence. That's an excellent segue to a larger project!
http://www.animalgame.com/play/faq.php
Notice there is no branching code any more. To follow a flow you start from the root tree.
Yes, that's what I was going for. Your design is deeper than mine, though. Thanks.
Ok so why did we build thingys? Well because things can now answer questions for themselves and we can build costumes on thingies and get them to run around on screen. Now we don't have to ask the user questions we can just send messages.
I'm not sure what that--doesn't the game go away at that point?<s>
(Like KILL! Ugh).
lol
All things that live, kill. Or, minimally, all organisms compete for resources that other organisms could use to survive.
So to summarize my suggestion: you use a tree construct to represent branching instead of using hard coded flows.
Good. That's the ball-park I was in.
(It is not really a linked list) You build objects that represent properties that have questions and answers. You can then build things that have these properties.
Yeah, I hesitated to use the term "linked list" but it's (non-technically) a list of linked items. I suppose, technically, it's an n-tree.
Thanks again!
===Blake===
Comments in message.
From: Blake Sent: Sunday, February 18, 2007 4:12 AM
Hey, Ron,
Thanks for the feedback. It is a fun question.
Welcome to the list.
Heh. I've been on this list since it started and on the general list for years, but I guess I don't make much of an impression.
I'm really sorry, I'm sure it's not you. I'm glad you choose to post your question, and I'm happy to see the newbies list be so successful!
...it may be better to let your son solve the problem on his own and then go back and build something else using some new techniques that you can show him.
Sorry if I hadn't made that clear: That's precisely what I am doing.
That's good. I think I posted this comment as much for you as for me. I learned the hard way by trying to teach math to my daughter. It didn't go well! So now I review homework, sometimes point out errors, teach some concepts later. It's not an easy transition to make, but it does work better (some).
Second there are a lot of possible designs for this problem. The implementation of the design should be kept separate from the design itself. Whether or not you use a text file or how you store the data is a detail. The details come easy once you have a good design. So focus on design first.
Right. I meant to draw contrast to a traditional state machine where things are fixed, and went to a specific detail.
That aside this is a fun question. (Although I really don't like the actual flow chart, killing and kids don't mix well in my mind. I know there are lots of killing video games but not that I let my child play)
Not to get sidetracked on the issue, but I introduced my son to computers and gaming at the age of...oh...15 months by having him sit on my lap and fire the weapons in Doom 2. I can't really explain in brief the extent of the positive changes this wrought. He's had an abiding love of games--including "violent" games--ever since. (I put "violent" in quotes for a lot of reasons that are also not on topic.<s>) Completely coincidentally, he's by far the most compassionate persion I've ever met. I've never met anyone so completely devoid of cruelty and so quick to help others in distress.
(Of course, results not typical, your mileage may vary. I filter out plenty of other things I think are bad for him; it's just that his list is different from other kids'.)
By the way, in case it's not obvious, this is a flow chart for the pen-and-paper RPG "Dungeons and Dragons", and is meant as a jokey simplification of that game.
I played DnD when I was in grade school. We had an after school club and it was really fun. What concerns me is the level of violence in video games today. I'm a bit out of touch with games. I saw a group of programmers in my last job set up a game server, I can't remember what it was, and they spent a whole lot of time at it. It was really violent. So what I know is mostly second hand. I read about violence and exposure to TV and Video games and the evidence seems to support a very negative impact on children, including violent activity, anti-social behavior and attention disorders. I remember reading about increased hand-eye development but I question the benefit of that considering the down side.
I'm not sure I really understand the whole concept very well. I also have read about children that are not well adjusted because of a lack of exposure to the things they will experience later in life. I suppose that if society of today requires a certain amount of desensitization then if we can't change society we should provide the right level of exposure.
I'm happy that your son is well adjusted and doing well. I'm sure that comes partly from having a good Dad. I wonder if the feeling of safety that comes from new experiences in your presence, like exploring the world but only in sight of Mom (one of the eight stages of development), accounts for your success. It makes me wonder if some of the negative impacts can not be accounted for because of the lack of supervision in TV and video games.
System: Enter Property Name: You: Scary System: Enter Question for Property Scary: You: Is it Scary? System: Answer to question Is it Scary?: You: yes
Ah. Yes. This is "Animals", in essence. That's an excellent segue to a larger project!
http://www.animalgame.com/play/faq.php
Notice there is no branching code any more. To follow a flow you start from the root tree.
Yes, that's what I was going for. Your design is deeper than mine, though. Thanks.
Ok so why did we build thingys? Well because things can now answer questions for themselves and we can build costumes on thingies and get them to run around on screen. Now we don't have to ask the user questions we can just send messages.
I'm not sure what that--doesn't the game go away at that point?<s>
Not really. I guess my point here is that you can use your properties to build real things. Those things can be very useful in many different ways. Say like a classification tree. Once you answer questions the system could give you the name of the thing you found. You found Caulerpa taxifolia. Or if you have your thing running around on screen and trying to talk to you, it seems silly to ask you if it's alive and talking. I guess I was trying, but not well, to show the benefit of properties to construct useful things.
(Like KILL! Ugh).
lol
All things that live, kill. Or, minimally, all organisms compete for resources that other organisms could use to survive.
Agreed. Since we are so off topic anyway, and I'm sure nobody else is bothering to read this far, I am quite well read on the theories of evolution. It is an extremely interesting field of study. It's also interesting to consider the effects of competition in human development. You don't have to go far to see the quick return to the mean, in things like the French Revolution, or the Russian removal of the Czar. I really believe that we are in deep trouble when we isolate ourselves and consume such vast resources. I like the OLPC project because I believe that projects just like that one will help to even out world resources and could help to bring peace. As humans maybe we can learn to share and manage the resources so that other species won't be wiped out in the process. After all it's true there are limited resources, but considering we have a very nice sun, there is still a lot to go around.
So to summarize my suggestion: you use a tree construct to represent branching instead of using hard coded flows.
Good. That's the ball-park I was in.
(It is not really a linked list) You build objects that represent properties that have questions and answers. You can then build things that have these properties.
Yeah, I hesitated to use the term "linked list" but it's (non-technically) a list of linked items. I suppose, technically, it's an n-tree.
Thanks again!
You are very welcome.
Ron
===Blake===
On Sun, 18 Feb 2007 06:21:14 -0800, Ron Teitelbaum Ron@USMedRec.com wrote:
That's good. I think I posted this comment as much for you as for me. I
Yeah, I'm definitely in "thinking out loud" mode. It's good to see how others think, too.
learned the hard way by trying to teach math to my daughter. It didn't go well! So now I review homework, sometimes point out errors, teach some concepts later. It's not an easy transition to make, but it does work better (some).
Ah. My kids are homeschooled so I have no outs there. It's still not so much teaching as sort of get-out-of-the-way while they learn.
I played DnD when I was in grade school. We had an after school club and it was really fun.
I'd guess you're slightly younger than I, then. When I was a teen, the issues raised with D&D were virtually identical to the issues being raised today about video games (and about comic books in the '50s, pulp fiction in the '30s, etc.), with the added twist of a few self-proclaimed experts insisting that D&D contained REAL SPELLS.
What concerns me is the level of violence in video games today. I'm a bit out of touch with games. I saw a group of programmers in my last job set up a game server, I can't remember what it was, and they spent a whole lot of time at it. It was really violent. So what I know is mostly second hand.
Well, of course, games are not violent so much as pretend-violent. And gamers tend to quickly break down a game into its numbers. Which is why games like Katamari Darcy and Viva Pinata can be phenomenally successful even among hardcore gamers, despite being opposed to the usual dark/gory/faux-serious that demographic gravitates toward.
In his "A Theory of Fun For Game Deisgn", Ralph Koster re-imagines Tetris as a game where you're a Nazi dropping Jews into a pit. It's an illuminating discussion.
I read about violence and exposure to TV and Video games and the evidence seems to support a very negative impact on children, including violent activity, anti-social behavior and attention disorders.
I've never seen anything that struck me as even remotely reliable. However, I do think TV and games are completely opposite. Television and movies are passively absorbed. Even in the best filmed entertainments, which engage you emotionally and intellectually, you have no control, and are therefore encouraged to accept what you see.
Games are meant to be beaten. Figured out. Controlled. Gamers expect to be Cause rather than Effect. One of the best references I can make here is to Adam Cadre's text adventure game "Photopia". It's the story of a girl who dies in a car accident, told backwards. You can't change this; the interactivity comes entirely from how you experience the character when she's alive. It's a very moving work, perhaps the most moving game I've ever played, and it pissed not a few people off because they had the gamer's expectation that they could keep the character from getting killed.
Anyway, this mindset (IMO) makes the player less susceptible to influence than the viewer. It's precisely why it's so difficult to create a game that rises to the level of art. ("Starflight" had a twist that completely altered the player's view of the game mechanic, not unlike the aforementioned Tetris/Nazi thing. But it's rare.)
I remember reading about increased hand-eye development but I question the benefit of that considering the down side.
Well, you can get those hand-eye development benefits playing any twitch game, regardless of context, I'd imagine.
I suppose that if society of today requires a certain amount of desensitization then if we can't change society we should provide the right level of exposure.
As I say, it's done nothing to desensitize my son. Well, yeah, maybe it's desensitized him to movie and game violence. :-) Real violence appalls him and I think he thinks violence even on the level of, say, boxing is pretty stupid.
OTOH, violence with survival value (say hunting or fishing) seem okay to him (though we haven't done anything like that yet).
I'm happy that your son is well adjusted and doing well.
Heh. My children aren't well-adjusted. They adjust the world.
It makes me wonder if some of the negative impacts can not be accounted for because of the lack of supervision in TV and video games.
Might be. There are six of us and we have one TV in the main room. The computers are also in the main room. And, again, it's about knowing your kid. My son, when he was two, we watched the movie "Phantoms". Eye-sucking aliens didn't bug him at all. But there's a scene where Ben Affleck, the town sheriff, describes how he left the FBI after accidentally shooting a child. =That= freaked him out. So I learned: No Ben Affleck. No, seriously, I discovered that in the context of the fantastic, anything goes, but if it were realistic, you had to be very careful.
No substitute for knowing your child.
I'm not sure what that--doesn't the game go away at that point?<s>
Not really. I guess my point here is that you can use your properties to build real things. Those things can be very useful in many different ways. Say like a classification tree. Once you answer questions the system could give you the name of the thing you found. You found Caulerpa taxifolia. Or if you have your thing running around on screen and trying to talk to you, it seems silly to ask you if it's alive and talking. I guess I was trying, but not well, to show the benefit of properties to construct useful things.
See my response to Todd as far as this goes.
You don't have to go far to see the quick return to the mean, in things like the French Revolution, or the Russian removal of the Czar. I really believe that we are in deep trouble when we isolate ourselves and consume such vast resources.
I agree with the former. As far as the latter, I would argue that our "vast consumption" is what makes things like the OLPC possible.
I like the OLPC project because I believe that projects just like that one will help to even out world resources and could help to bring peace. As humans maybe we can learn to share and manage the resources so that other species won't be wiped out in the process. After all it's true there are limited resources, but considering we have a very nice sun, there is still a lot to go around.
Our concern for other species--and even groups of men apart from us--is made possible by our vast wealth; we tend to deplore our materialism, but we neglect the positive things abundance brings. To a starving man, a spotted owl is dinner. To a man without shelter, a redwood is a roof.
The OLPC rocks. I hope they mass market to first world nations. It has the potential to change everything. Commoditize computing power completely.
I hope my children are able to benefit from and contribute to it.
===Blake===
Hello Blake,
B> Looking at the chart, it looks like spaghetti code, and reminds me of some B> of the stuff I did in BASIC. And that's sort of what he's doing within B> Smalltalk. I'm actually tempted to show him how it would look in BASIC B> using GOTOs and line numbers. It would have the advantage of being easy to B> see all in one glance. for things I would have considered a state machine in previous languages in Squeak I usually take a Dictionary.
I've only used them two levels deep up to now and for a real deep tree it's not appropriate.
But they are easy to follow by opening explorers on them and programming consists of going to the right dictionary typing:
self at: "I now want to handle this case" put: [ the Block of code to handle this].
Lately I put these Dictionaries into class vars and on the class side I have some file in/ out code using reference streams. (Tried this only with Dictionaries containing no code, but I guess it should work with blocks too.)
Cheers,
Herbert mailto:herbertkoenig@gmx.net
On Sun, 18 Feb 2007 02:48:46 -0800, Herbert König herbertkoenig@gmx.net wrote:
But they are easy to follow by opening explorers on them and programming consists of going to the right dictionary typing:
self at: "I now want to handle this case" put: [ the Block of code to handle this].
That's interesting. I wouldn't have thought of that.
Lately I put these Dictionaries into class vars and on the class side I have some file in/ out code using reference streams. (Tried this only with Dictionaries containing no code, but I guess it should work with blocks too.)
Thanks for the suggestion. I'll think on it.
===Blake===
You're building an expert system. There are well known patterns/ algorithms/architectures for that.
I developed ObjectiveCLIPS http://objectiveclips.com which is an open source framework for building this kind of thing in ObjectiveC on the Macintosh. A great book on the topic is http://www.amazon.com/ exec/obidos/redirect?link_code=as2&path=ASIN/ 0534384471&tag=blackbagopera-20&camp=1789&creative=9325
Basically you want a rules based production system based on the rete algorithm. This is important because decision trees are fragile and difficult to maintain.
CLIPS is a good free system to play around with. I've often wished we had a rete algorithm implementation in Squeak. http://www.ghg.net/ clips/CLIPS.html
Todd Blanchard
On Feb 17, 2007, at 4:11 PM, Blake wrote:
I'm half thinking-out-loud here and soliciting thoughts on a programming lesson. If this sort of thing bugs you, feel free to ignore.
My son is coding this flow-chart as a Q&A type application:
http://media.www.gamespy.com/articles/633/633817/img_2913464.html
So, it says, "You found something!" then asks "Is it alive?" and then branches out accordingly. I'm letting him muddle through with the idea of using his code as a platform to teaching him a better approach (or approaches).
Looking at the chart, it looks like spaghetti code, and reminds me of some of the stuff I did in BASIC. And that's sort of what he's doing within Smalltalk. I'm actually tempted to show him how it would look in BASIC using GOTOs and line numbers. It would have the advantage of being easy to see all in one glance.
But I want to, of course, show him a better approach and explain why it's better. My first thought was to make a state machine, but I don't think that'd be much better, in fact.
Then I thought of what I would do, professionally, in a similar context: The problem with the spaghetti code and even a state machine is that it's static, and adding bits and pieces tends to require everything to be massaged around the new parts. In the real world, I know that the chart's not going to be static.
I'd probably end up create a linked list of one-exit nodes and two- exit nodes.
So, that's what I'll probably show him.
The other thing I'd do, though, is put this all in an editable text file, like:
1,foundsomething,"You found something",alive 2,alive,"Is it alive?",friend,smash 2,friend,"Is it a friend?",lately,scary 1,smash,"Smash it with a stick!",shiny
But I'm wondering if this last wouldn't be too much.
Thoughts? _______________________________________________ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
On Sun, 18 Feb 2007 11:51:55 -0800, Todd Blanchard tblanchard@mac.com wrote:
You're building an expert system. There are well known patterns/ algorithms/architectures for that.
Thanks for the tips. I've saved them for later digestion. I've fallen behind on expert system technology apparently.<s>
However, the point isn't really to build an expert system. I've been teaching my son with Squeak for a while, and it was only the combination of PopUpMenu and the aforementioned chart that ignited his interest. He saw something he could imitate and extend/expand. So the fact that it's a sort-of expert system is incidental.
Where we're actually going, at least from all the signs, is an adventure game. And he's expressed an interest in doing a roguelike. (I'd kill for a smalltalk text interface right about now....)
Intriguingly, he doesn't really relate to eToys, and while we've used Stephane's Bots book to great effect, he's actually much more comfortable coding in the full Squeak. Strange.
===Blake===
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