Wikipedia:Reference desk/Archives/Computing/2012 September 10

= September 10 =

constructor inheritence in c++
Hello !why can not we inherit constructors in c++? i have read so many books.but i can not understand. can you please explain clearly? — Preceding unsigned comment added by Phanihup (talk • contribs) 00:58, 10 September 2012 (UTC)


 * C++ 11 supports constructor inheretance: C++11. Why not before? Because. 146.90.59.151 (talk) 01:55, 10 September 2012 (UTC)

'Transcluding' forum posts, possibly through RSS?
Would it be possible to transclude (using the Wikipedia definition) posts on phpBB forums, say, or even Yahoo! Answers on blogs like Livejournal, or anywhere at all with some code? (I was thinking about RSS since that's sort of how it works, but not sure if it could be transcluded in this manner.) 62.255.129.19 (talk) 03:20, 10 September 2012 (UTC)
 * Everything is possible: screenscraping is the ugly art of writing a program to grab contents of a web-page for programmatic use. If the source text is made available in a convenient, machine-readable format (like RSS), this greatly simplifies the necessary code.  Nimur (talk) 04:09, 10 September 2012 (UTC)

Keeping external hard drive in case of a fire?
Will keeping an external hard drive in a fridge or freezer in case of a fire keep the drive safe? Or will the moisture or freezing temperature damage the drive? I'm asking about normal external drives, not special ones. Are you ready for IPv6? (talk) 04:25, 10 September 2012 (UTC)


 * Why do you think that a fridge or freezer would be fireproof? AndyTheGrump (talk) 04:33, 10 September 2012 (UTC)
 * This forum thread goes over the second question. As for the first, I would think it depends on the severity of the fire. Dismas |(talk) 04:36, 10 September 2012 (UTC)
 * Best is probably to keep a backup in a separate physical location (say, a safe deposit box, or your desk at work, locked in a drawer). If you're worried that others might gain access to these, make sure it's encrypted.
 * Of course it's a pain to keep it up-to-date. That's presumably why a lot of folks like to use cloud-based backup services.  Personally I don't like that trend; I think it makes it too easy for the state to keep an eye on people. --Trovatore (talk) 07:47, 10 September 2012 (UTC)
 * They can already intercept your e-communications with arbitrary ease if they want to. Is there stuff on your hard drive that is more sensitive or telling than that? I sort of doubt it for most people. At least DropBox and most other serious services are encrypted, unlike most everything else you send through these here Internets. --Mr.98 (talk) 15:52, 10 September 2012 (UTC)
 * Dropbox may encrypt the data during transfer, but they hold the decryption key when it's stored on their service. So the Government can simply ask them for the decrypted data and Dropbox can provide it. Services/programs like Duplcati, Spideroak, Jungledisk encrypt the data on the client side before sending the data to the cloud. Therefore, only you have the decryption key and the service provider cannot access your data. - Akamad (talk) 22:28, 10 September 2012 (UTC)
 * Of course you can encrypt files yourself with something like PGP before you uplpad them to dropbox. Vespine (talk) 22:35, 11 September 2012 (UTC)
 * If it isn't convenient to use a separate location, (and you don't like "the cloud",) then a fireproof safe can be purchased at reasonable cost (less than the hard drive for a basic box). If you are expecting a fierce fire, then wrap it in (fibreglass, rock-wool) loft insulation for extra protection.    D b f i r s   08:39, 10 September 2012 (UTC)
 * However, consider that fire is only one risk for the HD, depending on where you live these could include things like earthquakes, tropical storms etc which the safe may not definitely protect against. And while a fireproof safe may provide some protection against theft, you probably shouldn't rule it out either. I would suggest if you're trying to finds ways to ensure a single backup in the same location as the main data (I'm presuming we're at least talking about a backup here, not the sole copy of the data) gives a very high degree of protection against data loss, you're mostly wasting your time. Nil Einne (talk) 10:09, 10 September 2012 (UTC)


 * One trick that I rather like is finding a friend/family member in a similar situation and agree to "mututal backup" i.e. you each have a drive/partition or just some space on the other person's computer/file server etc. which you can use for remote backup. Programs like CrashPlan make this a viable solution even for non techy users. It's cheaper than the cloud (free if you do it yourself using e.g. duplicity and FTP, or are willing to accept the limitations of free versions of commercial backup software). If you choose your backup partner carefully you certainly trust your backup provider and on the security issue, just encrypt your data before sending. Equisetum (talk &#124; contributions) 10:21, 10 September 2012 (UTC)
 * My solution is of course only free if you don't pay per MB for your internet access.Equisetum (talk &#124; contributions) 10:24, 10 September 2012 (UTC)


 * A fireproof container could be built using soft kiln bricks or other fireproof insulation material. Temperature rise will depend on duration of the fire and the heat capacity of the contents, storing the drive in a waterproof container surrounded by a volume of water could help. To illustrate: suppose you use a hollow sphere (makes the calculation easier) inside radius 10cm, outside 20cm, made of material with an insulation value of 20 W/m.K. (based on the properties of cementitious foam) A temperature difference of 500°C gives a heat flow of 63 W or 63 J/sec; the inside volume is about 4 liters; if filled with water, temperature would increase 13.5° C in one hour. If instead of water, only an object with low heat capacitance is inside, say 1 kg of lead, then the temperature increase would be 29°C per minute. (ignoring air and heat capacitance of the insulation...). Not saying a DIY project is the best solution though... Ssscienccce (talk) 11:15, 10 September 2012 (UTC)


 * I know this is an anecdote, but I don't trust fireproof safes. I know someone who collected coins, and stored them in a fireproof safe. When his house burnt down, the safe survived, but the coins were a melted mess inside. A freezer certainly isn't designed to keep the contents safe during a fire. The seals would burn away when exposed to fire. I agree with the others that off-site storage is the way to go if you really care about the backup surviving a disaster at your home. 209.131.76.183 (talk) 12:36, 10 September 2012 (UTC)
 * Fireproof safes typically rely on evaporation of water inside the insulation to provide the rated protection of 30, 60, 120, 180 or 240 minutes. These materials can lose water over time, reducing the effectiveness. The test conditions for fireproof ratings vary from country to country. For example, the U.L tests leave the safe in the furnace to cool down naturally, the B.T.U. in Germany does the same. The CSTB in France and J.I.S. in Japan hose down the safe after the rated duration. And some companies may advertise their products as "tested to UL standards", even when they failed the test. Ssscienccce (talk) 15:26, 10 September 2012 (UTC)

Having been a volunteer firefighter in the US for about 15 years, I'll point out some additional risks. If the container is in a wood frame building, the floor may collapse in the fire, causing the container to fall to the basement. A substantial amount of water may accumulate in the basement; 15 cm would not be at all surprising. Also, in case of a disaster, the building and data may be undamaged, but the owner may prevented from visiting the building for an extended time. Jc3s5h (talk) 22:36, 10 September 2012 (UTC)

Thanks guys. So it seems if it's in a freezer with a plastic bag over it, it needs to stay in that to absorb the moisture till it thaws. Are you ready for IPv6? (talk) 03:12, 11 September 2012 (UTC)
 * My mom keeps important documents in a fireproof lockbox shaped like a briefcase (which has the added advantage of being easy to carry out of a fire provided it's in a convenient spot). My external drive would fit inside it fine. - Purplewowies (talk) 03:40, 11 September 2012 (UTC)


 * Gah. When building a house, avoid flammable materials like the Plague. If there ain't enough fuel to support a 2-hour fire, there ain't any need for a fireproof containment which lasts for 2 hours either. It all boils (burns?) down to the 3 Little Pigs. Oink. 217.251.166.157 (talk) 14:28, 11 September 2012 (UTC)

This problem is similar to the one I have been thinking about. I currently have two 1 terabyte external hard drives that I regularly back my system up to, but both of them are located in my apartment. A fire in my apartment would destroy all copies of my files. So I definitely need an off-site backup. I don't trust cloud back-ups, so I think buying more drives and storing them in a bank deposit box would be a good idea. From what I've asked over at the Finnish Wikipedia, rents for bank deposit boxes are in the order of less than 100 € per year, which is easily within my budget. The trouble might be in finding a vacant bank deposit box. Then there's of course the problem that even if the drive is safe from outside dangers, the mere fact that it's a physical object means that it's going to deteriorate over time. J I P &#124; Talk 17:59, 13 September 2012 (UTC)