Being able to loosen a pre-condition facilitates polymorphism but it also leads to situations like the one that I described, where a subclass losens the preconditions of a parent to the point where the intent of the pre-condition in restricting the class and enforcing the intent of the type is lost.
What this actually shows is that there are reasons for not allowing a pre-condition to be tightened (breaks polymorphism) and reasons for not allowing it to be loosened (breaks the intent of the pre-condition). What are you left with? A mechanism that's only theoretically useful since the only truely valid pre-conditions must be defined at the top of the class hierarchy.
If you allow a subclass to loosen a pre-condition it's no longer a true subclass.
For example if you determine that for the class apple there is a precondition "be a fruit" then you subclass to green apple, the original precondition must hold otherwise you could have a subclass of apple called carrot. Very weak example/analogy but you get the idea.
I believe this is already the case. Holders of patents are required to license the use of their patent for "a reasonable fee." I don't believe they are allowed to simply refuse to allow other parties to use their technology. It's part of the condition of being allowed to hold the patent.
It all hinges on the definition of "a reasonable fee". If you're allowed to factor R&D into a life saving drug that costs millions to develop but cents to manufacture, you're then allowed to sell it for a small fortune. Never mind that people will die for lack of something you can easily manufacture. The whole "what's the incentive for developing it otherwise" argument also comes into play here. Bottom line is that's self serving nonesense. People can and will invest in something if money can be made over the longer term, so forcing a reasonable price to be well...affordable by the man on the street would only result in a situation where companies recover their costs over a much larger period, and I believe the R&D will happen. (In any case what the hell's the point if no one is allowed to use it or rediscover it until the patent expires. It only serves to make people richer, while average people without great wealth die). Companies however hire lawyers to ensure that they recover costs over a shorter period - otherwise executives can be sued by the shareholders for not looking after the shareholder's interests.
Don't be so obtuse on purpose. People go to the movies to use the large screen, and make a night out of it. They may also see a film before it becomes available to watch on DVD/Video in their own home on their own equipment. You're basically paying rental on the theatre, which is why most movie tickets cost about the same price. Even this is an artificial system set up in a day and age where owning a large screen that could fill your field of vision was beyond the reach of the man on the street. It's still a luxury but well within reach for many to have their own home theatre now.
Gee I wonder why there are so many sensationalist headlines to choose from? Could it be because companies have stooped as low as threating disproportionate fines and jail for people copying a song off the internet? Could it be because we're bombarded with images that equate copying something to stealing? No must be irrational hatred.
I'd like to shake you and scream "wake up" in your face.
Patents are flawed. Copyright law is flawed. Trademark law is flawed.
All 3 are very artificial means of attempting to return value to a creator for his or her work. All 3 counteract themselves and increase the problems they're intended to solve.
We need to ditch the existing systems and find a way to compensate creators and inventors without hindering the public's ability to use their creations. Specifically any form of compensation must allow things that are easily copied to be easily copied legally and without artificial restriciton (ie no DRM).
Before some arrogant fool comes back with a Wikipedia link to Communism like the last time I posted something similar to this, I'm not talking about a political system, and I'm not talking about group ownership of anything. I'm talking about a system of compensation that depends on the use of a product rather than possessing a copy of it. I'm not saying I have all the technical solutions for this.
I'm sorry if this sounds harsh but technically you almost missed your flight because you were inept with the technology.
You'd never used this technology before, had no training in using it, don't know its limitations and your test was to rely on it? Gimme a break. You should have punched it into the GPS, pulled over, and then compared with the paper based maps. A few minutes checking over your assumption and you'd not have been anywhere near as late.
Would you pick a random web page and believe everything you read on it too?
Your argument is that since you and your colleagues work in an environment where you have the time to fix this, no one else could possibly.
Well here's a few reality checks for you:
1) People will do amazing things in their spare time. Some of these people would only be to glad if someone would hire them to do some work on the side. Not all are basement bound computer nerds. The world's a big place.
As just one example, I'm constantly amazed at the complexity of Microsoft Flight Simulator aircraft that are put out as freeware. Hundreds of Gigabytes of freeware out there - some of it outstanding quality that's much better than the default Microsoft planes and very comparable to payware. We're talking hundreds or thousands of man hours on models, flight dynamics gauges, research etc. so yes this is a game but this is not trivial stuff.
If someone thinks its worth their spare time they make time to do it.
2) If the source code is available at the very least it can be audited by security experts etc. Often if the software is well written small tweaks which are impossible to make on closed source are easy with open source and won't take that much time. If it's a vital feature you happen to need it's much better to spend this time than try to beg a vendor to do it.
RMS is a bit on the fringe but if you've ever heard him speak about what got him started with his open source crusade, it was that he was refused access to the source code for a printer driver that had a bug and which he needed to fix. Basically there are very good reasons for wanting to have the source code to software you haven't written, but it's rarely that you want to use it as a basis for some kind of redesign or enhancement of the product.
Congratulations on be pwned by a major corporation because you like their product. Perhaps you should sell Apple Mac advertising space on your forehead.
Re:Apple is going to make a killing...
on
Going To Boot Camp
·
· Score: 1
So you're saying that if a very intelligent person is using a Mac it's definitely because they choose to and has nothing to do with the fact that it may be a policy at their place of employ, because they need interoperability, because they simply haven't tried the alternatives for for any one of a thousand other good reasons?
Actually dispose/finally language constructs are a convenience too. You can easily write and consistently call a routine to cleanup after yourself whether or not a particular routine fails.
The point I was making is that this idea of design by contract is not revolutionary or new to Eiffel. Eiffel just provides a language construct that makes it easier not to forget or blow your design by contract. That doesn't make Eiffel useless, but one language feature is never a good reason to switch languages.
Actually all this is "akin to saying" is that one language feature does not a language make. What you've just demonstrated is a technique of argument called reductio ad absurdum. Check this out if you're not familiar with the term:
You can do design by contract in any language. You can do the same thing in any other language but you have to always remember to call super methods when you are doing your pre and post assertions otherwise your subclasses won't adhere to the contract. What Eiffel gives you are contracts as part of the language.
Disclosure: I haven't used Eiffel since about 1998 when my undergrad degree software engineering courses were taught using the language, so I'm not complete current on the language.
So you're saying that it doesn't matter if it interfeers with the employee's work, it's more important that you as a system administrator are permitted to secure the system using the lowest common denominator.
I have a much simpler solution for you. Ditch the PC and go back to paper based. Only approved forms are allowed to be passed to other people, either within the company or external to the company. Then on the way in and out of the company check and photocopy every piece of paper that the employee is carrying. How secure would that be?
Not practical you say? Well neither is asking permission to install every piece of software you require, particularly if you're working in IT. Alternatively you could hire competent people and give them adequate training to use the tools they require. Too hard though isn't it? Everyone wants something for nothing these days. Employees want free access to everything. Employers want 80 hour work weeks while paying for 40. Employers own the equipment and have the power and can and will do whatever they want whether that backfires in their faces or not. End of discussion.
Thin clients are useless pieces of crap. They're fine if all your employee ever does is email and write word documents, and occassionally look at your company intranet or the internet.
The personal computer revolution started because computers are versatile multi-purpose machines. Lots of people do lots of very different things with them and not all these things are easily replaced with a thin client solution. How quickly people forget that.
Dear annoymous QLD coward. I was having a rant about the Labour Party since once upon a time I use to vote for them and still wish they vaguely represented my beliefs. If you read the summary (not even the article) you'll notice that it states all parties banded together to pass this one.
Please enjoy the rest of your day despite having your head firmly planted where the sun don't shine. Ironic for a QLDer no?
Seriously these politicians have just gone plain loopy and it's all because the labour party has gone into a tailspin.
State labour in NSW (where Sydney is and the biggest state) has been unable to fix Sydney's transport problem and keeps closing roads around new tollways stuffing up public transport...not to mention they haven't been able to improve a constantly deteriorating health care system. Federal labour can't get enough votes to put up any serious opposition and the opposing party has a majority in both houses. The young labour party has recently been in the papers for calling for conscription - a total about face on their previous postion. Recently the labour party also did an about face on their position regarding forcing ISPs to filter pornography (and are now in favour of this with all of its technical problems). What's more they have personality issues within the party (nothing new in politics but this is when a party has to band together to survive).
I'm an Australian who feels I have zero representation. Not one politician here is even trying to make this country better...not even for the votes.
Don't get me started on Apple. I'm still holding a grudge from my old Apple IIe. I very begrudgingly bought a video iPod last year, and my fiancee had a photo ipod. We've already had issues with return policy (her first one came pre-scratched but we did manage to get a refund). My click wheel center isn't quite right. Sometimes takes two presses. I can only fight so many battles though and last year it was the dead Inspiron and a dying Nikon D70. Every piece of equipment I own is very well looked after - in a special case etc. Never dropped or handled with greasy hands...
My experience is that warranty service has gone down the toilet in the last few years.
YMMV is always true of any company, but I was truely in phone support hell with this incident with Dell, and it's the only personal experience I have to go by. The least I can do is balance all the positive anecodotes with a tale of what can happen if things don't go well. I think a lot of it has to do with whether your computer is still under a Dell warranty, who the technician is in your local area, and which call center services your country.
Note also that after all that mess I didn't get anything but an apology from Dell. The bank which directed me to the wrong insurance company for my claim didn't even give me that. The insurers were downright rude.
Regardless, 4 months is too long to fight to have a laptop fixed. The technician trying to install the service tag was incompetent. The whole thing disgusted me.
He asks for no money and does a so so job. Do you bad mouth him or make him dinner?
Now what if a professional plumber does a so so job and charges you more than you think it's worth?
Different situation right?
FOSS is your uncle Bob. He ain't asking for anything and he's contributing his time and effort so you're either greatful regardless of the result (particularly if he does manage even a mediocre fix) or you need to be slapped into the real world and told the world owes you nothing.
MS/Apple is the professional plumber. You call in MS Office when you want the job done professionally and properly and you expect to pay for it. If it's not done right you're not happy.
Key point here for most users is that FOSS is free as in beer. Most users couldn't fix the source code worth a damn and don't want to know how.
Good luck trying to get service if something goes wrong.
I went with a standard one year warranty on my Dell 5150. Motherboard died due to a design flaw Dell have never admitted to (casing wears into motherboard components). Basically it started with random shutdowns whenever you'd touch the left side of the computer, and quickly progressed to a computer that wouldn't boot. This laptop was treated very well too.
In the end it took about 4 months to sort out. I had bought using a credit card which doubled the warranty but had to get Dell to state that the fault would have been covered under warranty had it occurred in the warranty period. I must have spent about 12 hours on the phone with Dell staff that could bearly speak English, and an insurer that was admiant they would not process the claim under warranty until I had this in writing from Dell.
Then when they repaired it, it took 5 visits from incompentent technicians who couldn't set the service tag Id.
In the meantime I begrudgingly bought an Inspiron 9300 from Dell, this time with top level warranty - the price was about AUD1000 cheaper than anything else with similar specs and I'm not so affluent I could turn that down. However I'm dreading the day I have to deal with Dell support and am hoping against hope this machine outlives its warranty. The old machine went to my fiancee, on the understanding that she uses it till it dies and we won't try to repair it.
Slashdot Mirror
Being able to loosen a pre-condition facilitates polymorphism but it also leads to situations like the one that I described, where a subclass losens the preconditions of a parent to the point where the intent of the pre-condition in restricting the class and enforcing the intent of the type is lost.
What this actually shows is that there are reasons for not allowing a pre-condition to be tightened (breaks polymorphism) and reasons for not allowing it to be loosened (breaks the intent of the pre-condition). What are you left with? A mechanism that's only theoretically useful since the only truely valid pre-conditions must be defined at the top of the class hierarchy.
If you allow a subclass to loosen a pre-condition it's no longer a true subclass.
For example if you determine that for the class apple there is a precondition "be a fruit" then you subclass to green apple, the original precondition must hold otherwise you could have a subclass of apple called carrot. Very weak example/analogy but you get the idea.
Person/s cannot refuse usage of patent.
I believe this is already the case. Holders of patents are required to license the use of their patent for "a reasonable fee." I don't believe they are allowed to simply refuse to allow other parties to use their technology. It's part of the condition of being allowed to hold the patent.
It all hinges on the definition of "a reasonable fee". If you're allowed to factor R&D into a life saving drug that costs millions to develop but cents to manufacture, you're then allowed to sell it for a small fortune. Never mind that people will die for lack of something you can easily manufacture. The whole "what's the incentive for developing it otherwise" argument also comes into play here. Bottom line is that's self serving nonesense. People can and will invest in something if money can be made over the longer term, so forcing a reasonable price to be well...affordable by the man on the street would only result in a situation where companies recover their costs over a much larger period, and I believe the R&D will happen. (In any case what the hell's the point if no one is allowed to use it or rediscover it until the patent expires. It only serves to make people richer, while average people without great wealth die). Companies however hire lawyers to ensure that they recover costs over a shorter period - otherwise executives can be sued by the shareholders for not looking after the shareholder's interests.
It's a really sick game.
Don't be so obtuse on purpose. People go to the movies to use the large screen, and make a night out of it. They may also see a film before it becomes available to watch on DVD/Video in their own home on their own equipment. You're basically paying rental on the theatre, which is why most movie tickets cost about the same price. Even this is an artificial system set up in a day and age where owning a large screen that could fill your field of vision was beyond the reach of the man on the street. It's still a luxury but well within reach for many to have their own home theatre now.
Gee I wonder why there are so many sensationalist headlines to choose from? Could it be because companies have stooped as low as threating disproportionate fines and jail for people copying a song off the internet? Could it be because we're bombarded with images that equate copying something to stealing? No must be irrational hatred.
I'd like to shake you and scream "wake up" in your face.
I really hate personal attacks by anon coward. Aptly named. Shows a lot of guts and maturity.
Bzzzzzt. Wrong. No.
Patents are flawed.
Copyright law is flawed.
Trademark law is flawed.
All 3 are very artificial means of attempting to return value to a creator for his or her work. All 3 counteract themselves and increase the problems they're intended to solve.
We need to ditch the existing systems and find a way to compensate creators and inventors without hindering the public's ability to use their creations. Specifically any form of compensation must allow things that are easily copied to be easily copied legally and without artificial restriciton (ie no DRM).
Before some arrogant fool comes back with a Wikipedia link to Communism like the last time I posted something similar to this, I'm not talking about a political system, and I'm not talking about group ownership of anything. I'm talking about a system of compensation that depends on the use of a product rather than possessing a copy of it. I'm not saying I have all the technical solutions for this.
I'm sorry if this sounds harsh but technically you almost missed your flight because you were inept with the technology.
You'd never used this technology before, had no training in using it, don't know its limitations and your test was to rely on it? Gimme a break. You should have punched it into the GPS, pulled over, and then compared with the paper based maps. A few minutes checking over your assumption and you'd not have been anywhere near as late.
Would you pick a random web page and believe everything you read on it too?
Your argument is that since you and your colleagues work in an environment where you have the time to fix this, no one else could possibly.
Well here's a few reality checks for you:
1) People will do amazing things in their spare time. Some of these people would only be to glad if someone would hire them to do some work on the side. Not all are basement bound computer nerds. The world's a big place.
As just one example, I'm constantly amazed at the complexity of Microsoft Flight Simulator aircraft that are put out as freeware. Hundreds of Gigabytes of freeware out there - some of it outstanding quality that's much better than the default Microsoft planes and very comparable to payware. We're talking hundreds or thousands of man hours on models, flight dynamics gauges, research etc. so yes this is a game but this is not trivial stuff.
If someone thinks its worth their spare time they make time to do it.
2) If the source code is available at the very least it can be audited by security experts etc. Often if the software is well written small tweaks which are impossible to make on closed source are easy with open source and won't take that much time. If it's a vital feature you happen to need it's much better to spend this time than try to beg a vendor to do it.
RMS is a bit on the fringe but if you've ever heard him speak about what got him started with his open source crusade, it was that he was refused access to the source code for a printer driver that had a bug and which he needed to fix. Basically there are very good reasons for wanting to have the source code to software you haven't written, but it's rarely that you want to use it as a basis for some kind of redesign or enhancement of the product.
Congratulations on be pwned by a major corporation because you like their product. Perhaps you should sell Apple Mac advertising space on your forehead.
So you're saying that if a very intelligent person is using a Mac it's definitely because they choose to and has nothing to do with the fact that it may be a policy at their place of employ, because they need interoperability, because they simply haven't tried the alternatives for for any one of a thousand other good reasons?
Who is this Jebus of which you speak? For he sounds like a wise man and I wish to subscribe to his newsletter!
Actually dispose/finally language constructs are a convenience too. You can easily write and consistently call a routine to cleanup after yourself whether or not a particular routine fails.
The point I was making is that this idea of design by contract is not revolutionary or new to Eiffel. Eiffel just provides a language construct that makes it easier not to forget or blow your design by contract. That doesn't make Eiffel useless, but one language feature is never a good reason to switch languages.
Actually all this is "akin to saying" is that one language feature does not a language make. What you've just demonstrated is a technique of argument called reductio ad absurdum. Check this out if you're not familiar with the term:
http://en.wikipedia.org/wiki/Reductio_ad_absurdum
Lucky you. Where I work they just blocked all web based email despite legitimate business arguments to keep it.
Sammy
You can do design by contract in any language. You can do the same thing in any other language but you have to always remember to call super methods when you are doing your pre and post assertions otherwise your subclasses won't adhere to the contract. What Eiffel gives you are contracts as part of the language.
Disclosure: I haven't used Eiffel since about 1998 when my undergrad degree software engineering courses were taught using the language, so I'm not complete current on the language.
So you're saying that it doesn't matter if it interfeers with the employee's work, it's more important that you as a system administrator are permitted to secure the system using the lowest common denominator.
I have a much simpler solution for you. Ditch the PC and go back to paper based. Only approved forms are allowed to be passed to other people, either within the company or external to the company. Then on the way in and out of the company check and photocopy every piece of paper that the employee is carrying. How secure would that be?
Not practical you say? Well neither is asking permission to install every piece of software you require, particularly if you're working in IT. Alternatively you could hire competent people and give them adequate training to use the tools they require. Too hard though isn't it? Everyone wants something for nothing these days. Employees want free access to everything. Employers want 80 hour work weeks while paying for 40. Employers own the equipment and have the power and can and will do whatever they want whether that backfires in their faces or not. End of discussion.
Thin clients are useless pieces of crap. They're fine if all your employee ever does is email and write word documents, and occassionally look at your company intranet or the internet.
The personal computer revolution started because computers are versatile multi-purpose machines. Lots of people do lots of very different things with them and not all these things are easily replaced with a thin client solution. How quickly people forget that.
Dear Dantoo,
I think this link may interest you:
http://www.bartleby.com/61/43/P0144300.html
Dear annoymous QLD coward. I was having a rant about the Labour Party since once upon a time I use to vote for them and still wish they vaguely represented my beliefs. If you read the summary (not even the article) you'll notice that it states all parties banded together to pass this one.
Please enjoy the rest of your day despite having your head firmly planted where the sun don't shine. Ironic for a QLDer no?
Seriously these politicians have just gone plain loopy and it's all because the labour party has gone into a tailspin.
State labour in NSW (where Sydney is and the biggest state) has been unable to fix Sydney's transport problem and keeps closing roads around new tollways stuffing up public transport...not to mention they haven't been able to improve a constantly deteriorating health care system. Federal labour can't get enough votes to put up any serious opposition and the opposing party has a majority in both houses. The young labour party has recently been in the papers for calling for conscription - a total about face on their previous postion. Recently the labour party also did an about face on their position regarding forcing ISPs to filter pornography (and are now in favour of this with all of its technical problems). What's more they have personality issues within the party (nothing new in politics but this is when a party has to band together to survive).
I'm an Australian who feels I have zero representation. Not one politician here is even trying to make this country better...not even for the votes.
Don't get me started on Apple. I'm still holding a grudge from my old Apple IIe. I very begrudgingly bought a video iPod last year, and my fiancee had a photo ipod. We've already had issues with return policy (her first one came pre-scratched but we did manage to get a refund). My click wheel center isn't quite right. Sometimes takes two presses. I can only fight so many battles though and last year it was the dead Inspiron and a dying Nikon D70. Every piece of equipment I own is very well looked after - in a special case etc. Never dropped or handled with greasy hands...
My experience is that warranty service has gone down the toilet in the last few years.
YMMV is always true of any company, but I was truely in phone support hell with this incident with Dell, and it's the only personal experience I have to go by. The least I can do is balance all the positive anecodotes with a tale of what can happen if things don't go well. I think a lot of it has to do with whether your computer is still under a Dell warranty, who the technician is in your local area, and which call center services your country.
Note also that after all that mess I didn't get anything but an apology from Dell. The bank which directed me to the wrong insurance company for my claim didn't even give me that. The insurers were downright rude.
Regardless, 4 months is too long to fight to have a laptop fixed. The technician trying to install the service tag was incompetent. The whole thing disgusted me.
He asks for no money and does a so so job. Do you bad mouth him or make him dinner?
Now what if a professional plumber does a so so job and charges you more than you think it's worth?
Different situation right?
FOSS is your uncle Bob. He ain't asking for anything and he's contributing his time and effort so you're either greatful regardless of the result (particularly if he does manage even a mediocre fix) or you need to be slapped into the real world and told the world owes you nothing.
MS/Apple is the professional plumber. You call in MS Office when you want the job done professionally and properly and you expect to pay for it. If it's not done right you're not happy.
Key point here for most users is that FOSS is free as in beer. Most users couldn't fix the source code worth a damn and don't want to know how.
Good luck trying to get service if something goes wrong.
I went with a standard one year warranty on my Dell 5150. Motherboard died due to a design flaw Dell have never admitted to (casing wears into motherboard components). Basically it started with random shutdowns whenever you'd touch the left side of the computer, and quickly progressed to a computer that wouldn't boot. This laptop was treated very well too.
In the end it took about 4 months to sort out. I had bought using a credit card which doubled the warranty but had to get Dell to state that the fault would have been covered under warranty had it occurred in the warranty period. I must have spent about 12 hours on the phone with Dell staff that could bearly speak English, and an insurer that was admiant they would not process the claim under warranty until I had this in writing from Dell.
Then when they repaired it, it took 5 visits from incompentent technicians who couldn't set the service tag Id.
In the meantime I begrudgingly bought an Inspiron 9300 from Dell, this time with top level warranty - the price was about AUD1000 cheaper than anything else with similar specs and I'm not so affluent I could turn that down. However I'm dreading the day I have to deal with Dell support and am hoping against hope this machine outlives its warranty. The old machine went to my fiancee, on the understanding that she uses it till it dies and we won't try to repair it.