“suppose we have a class of Animal. because this is Animal class it can have much variety of Animal in the future. but for starters, let say if we have four different animals: Cat, Dog, Horse, and an Elephant. now, these animals have some behaviors such as sleep, run and carry. the rule for implementing the behaviors is to prevent any duplication of code, copy-and-paste is not good. i have defined several behaviors to you, but there will be more additional behaviors in the future. here’s the specific behaviors for the animals. all animals will be able to sleep and use the same sleep function. all animals can run, but each animal runs differently. only Elephant and Horse can carry things. remember, because we may have gazillions of classes in the future, any additions should have minimal impact to the module. build me your design.”

so I did.. here it is:

now, maybe it is not the best design in the world, but it is enough to satisfy his scenario. but i found out that the he is kind of have mixed reaction about my design. mostly he is kind of expected this design and kind of bored to my solution. however, how i separate the behavior to interfaces seems to surprised him a bit.

i cant really call this design is good, especially if we have a thousand of behaviors to implement, then this might not be the best. everything that describe the animal behaviors should probably best implemented in the animal class, but implementing abbilities like ‘carry’ using interface is often preferable.

going back to the interview, he then said that this design have a problem. he then asked me to add another premise: “now, suppose that I want to have a big dog. but this big dog can carry things around. this carry will be the same with the Horse and Elephant carry. and I do not want you to copy paste your code.”

this premise sounds fishy, and indeed it is strange. the while concept itself is strange. however, trying to meet his demand, i revised the design to this:

i just put a dog inside the big dog and then add a Run() method to be forwarded to the Dog instance. no, it is not a good design. this design is driven by a premise that i can’t use the same code twice, which is in this case Carry() or so he presume (later on this).

seeing that I overcome his tricks, he said again that this design still have problems. he then added another premise: “now, i want for the Elephant and Dog to be able to Play(). the same play should be used for both of the class.” at this point i understand, that he’ll just keep adding methods until i forfeit. he then says that this is the problem with my design, is that my design can’t cope with new methods without affecting the whole system. of course i suggest on doing refactoring, but he said that refactoring will affect the system too much even if it have unit tests.

so we did debate a little bit for more and i think, think and think, how to create a composible function that can be reflected on the interface of the classes. i suggest using a command-mapped interfaces, designed a series of chained commands (but that involves lots of casting = ugl. you might think of chain of command here, but chain of command works if you have one same virtual method, while in this case we have run, sleep, play…. doesn’t work right?). he then criticized my CarriableAnimal and said that this is only one behavior if you have lots of behaviors, like i said before, we’re going to add a lot of numbers of behaviors in the future, you’d add these classes around?

 so I was forced to redesign my code again. one of my suggestion came out like this:

of course this is just a desperate attempt to probe what he wants me to do. he pointed out if i were to add new behavior, i’d have to write exceptions for all the class that doesn’t implement the behavior. another is to implement the strategy pattern but there are problems with that, so i ruled it out.

after much struggling we ran out of time, and so he said he’ll give me the correct answer:

i almost fell off my seat…

it is basically the strategy pattern. and he explained it that this solves everything. what he didnt realize is that this very very much violates what he’s been asserting the whole time, this is also very wrong in software designs, and this design has almost zero usability, and implementation-wise problematic.

lets start with the false assertions. in order to implement this, then all the classes that’s going to have a new behavior added will need a code to hold the new behavior instance and to create the proxy method (= copy-pasting the same code through all the classes because the behavior can only exists selected classes only and no apparent hierarcy. eventhough it exists, i suspect to be insignificant based on his scenario). he did managed to isolate the problem within the class all the time though, given there’s no effective hierarcy. second, if there were hundreds of classes to be added this behavior, then the modification would be made hundreds of times as well.

now, let see from software design. what on earth have he made? the notion of object abstraction is not even apparent inhis design. he is abusing inheritance just to write less code. while he is trying to reuse code, but this is not the way to reuse code.

the fact that I can’t use a Horse from it’s abstract form Animal already poses question. the fact that Run() behavior is separated from Horse poses another question. what does Run do? It is completely independent from Horse. it can’t change any Horse state, so, what’s the use? put it in another term, if i have a behavior that doesn’t effect the owner of that behavior, is that behavior appropriate for the entity? it is useless. it might have as well as good as implementing it as static helper method. of course, if we want to change some detail implementation then strategy pattern is good.

from usability point of view, this is a dud. think about how you’d use these classes? you can’t do anything with the Animal base class, so you’d have to access the concrete class directly. now, suppose a controller have a method that process every animal that can play, how’d you do that? overloading the method parameter with everyknown class that implement the play method? what an absurd!

so that is my experience interviewing with a person who claims to be expert in OODA (he even calls everyone who wrote book on OODA doesn’t know what the real world and their books are rubbish), but doesn’t really know what he’s talking about. this is just some of my arguments, i still have a lot more, but you can see how bad this not-so-of-a-solution solution is.

i’m not trying to say that he’s a bad guy or anything, it just that he doesn’t really understand the real deal while pretending and saying he does. at least he knows about OODA, unlike most programmer that i’ve been working with. (now you know how sucks my job is right now).

 the problem arises when i tried to use find to get an entry. suddenly all hell break loose. all those cryptic stl error messages pouring down in my error window and it forced me to decrypt the messages one by one. the problem seems to originate from the inavailability of string operator==. so, i figured that the string operator== needs to be defined. no sweat. bool operator== ( const string& left, const string& right )… that should do it. but no, the error just wont get away. okay… maybe the pair operator== needs to be defined: bool operator== ( const pair<string, string>& left, const pair<string,string>& right )… no sweat.

again, i tried to recompile it, but the error just refuses to go away. what happened? doh… i tried various thing. i changed the pair to a pair of ints, it went smooth. i tried various combinations, i tried putting the find logic itself out from the funtion and put it in the source, but to no effect. after i tried for a while, i thought it is the time to try google. so i did. I surfed through the forums, but c’mon no forum will discuss this kind of problem specifically right? instead, i found a hint. written in a forum is a small advice: ‘put it inside the std namespace’. then it struck me! damn, i declared the operators outside the namespace! i put it inside the namespace cage, and… voila! everything works fine.

things that i learn:
1. mind the namespace.
2. decrypt stl messages by means of substitution, eg: basic_string<char, chartraits> = string
3. don’t blame the library. 99.99% of mistake is of your own doing (as i have written before)
4. respect the semantics.

about no.4, i have given a thought why string doesn’t have operator== defined. i dont have the full answer, but i guess it might be because of performance problem. or, because of semantic problem.

i didnt really follow his steps after that, but a couple of days later, another thread started by him in the general forum saying goodbye to all the people in the forum emerged. he claimed that the people that harassing him in the general forum has followed him to the tech forum and continue on harassing him there, and that that was it. he had enough and decided to leave c9 for good. i tried to look a bit in the tech forum and couldnt really find the post that offended him, but i guess, hes a very touchy guy. so, i replied to his thread saying that he have to learn to accept that this is how the internet is.

i dont know how this will turns out, the mods are actually pretty angry because the newcomer posted these kind of flame-bait and finally creating threads saying goodbyes (not really a good attitude, right?). but it got me thinking, so how do we suppose to post in a forum…

honestly, back then i think im one of the touchy people like this newcomer. i thought that internet people are just ruthless people that talks what they want without thinking about anyone else. but as time goes, i realize that while some of that claims are true but that they are mostly not motivated by ill intention. its a matter of expressing one self. people expresses themselves in various kind of ways. and posting in a forum is also a form of expressing one self. people who like to posts are people that likes to express themselves in writing. i, am one of those people. and i realize that when i want to express something id really like to have all the freedom of expressing one thought, one feeling in a series of letters. this, might led to a very expressive message sent to other people. while it is not harmless to the mind of the writer, some people sometimes took these sentences to heart and sometimes it stabs them in their heart. this is really an unfortunate thing because i expect that most of people doesnt really mean it like that. but what can be said, it is the nature of words. the posts that the writer wrote are what makes them what they are. i also noticed some people realize this tendency and chose not to post if its not important. some people, tried to strict themselves by reading and re-reading and editing their posts again and again (im one of these kind of people). but most of the people just doesnt care about what they wrote. ‘fire and forget’ types.

i agree that manner does have it place in the internet. to be curtious and accepting to others is a very good attitude. however, in the internet we dont meet face to face. we stared at a screen with a bunch of letters on them. we tried to visualize what kind of person the poster is. we hope that the poster will be avery nice person, but when the post offended us we tend to imagine the poster as the devil himself. if what is said in a post can be conveyed as like talking directly face-to-face, like a friend to a friend, then maybe we wont be so sensitive towards words. alas, words are the only clue we have. i know the general concencuss is to remind everyone to be more polite, and receiving and curtious toward others in the internet. but you and me know that that is the ideal world we are talking about. in reality, there is nothing we can do, and not much people really care to do. afterall, internet is freedom. and to have an artist not to paint permanently, you’ll have to cut his arms. this is the internet, and it is not as sweet as you might thought. learn to accept, and deal with it.