Computing desk | ||
---|---|---|
< February 10 | << Jan | February | Mar >> | February 12 > |
Welcome to the Wikipedia Computing Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
I want to download Apache Maven, but their website has 18 download links, just for the latest version! Which one do I click? -- Ypnypn ( talk) 01:35, 11 February 2013 (UTC)
apache-maven-3.0.4-bin.zip
. The .md5
and .asc
files are for helping you to feel assured that the mirror (server) you’re downloading from has given you the authentic file and not something else, but if you’re on Microsoft Windows, it’s (comparatively) absurdly involved to utilize either of those, so you may as well just ask how to in another question if you are interested (after all, if you’re on Microsoft Windows, you’re clearly already content downloading random executables with little idea of their authenticity and running them :/ :p). ¦
Reisio (
talk)
02:56, 11 February 2013 (UTC)I was reminded of this while looking for my spare modem recently. A few years back, I noticed all 3 modems I had used a transformer with an AC output, 2 with 9V and one with 18V. It's easy to find ones using similar AC PSUs from a quick search e.g. [1] 15 VAC, [2] 24 VAC, [3] another 9 VAC, [4] unclear VAC.
While many of these are old, and I'm not suggesting all or even most ADSL modems use AC (I'm not sure what does with built in wireless routers use, and obviously ones which supplies solely by USB as well as PCI, PCI express and ones built in to laptops must use DC), it does seem quite a lot to me. Beyond those used by ADSL modems, all the other devices I've used, e.g. network switches, (standalone) wireless routers, USB DVB-S receivers (which generally used an external PSU), DECT bases with digital answering machines, laptops, (also external HDDs, battery chargers, mobile phones but these are even less surprising), always seem to use a DC output PSU. Of hand, the only other device I know of which use an AC adapter are 12V halogens, although the reason here is more that the halogens don't care (and the supplies are usually internally to the device); although I'm sure there are a lot of other devices that do use AC adapters (probably some music equipment?).
When I first noticed after a long time searching I think I found someone suggesting that some component works best with AC but can't find it again and it may have just been a forum. Most of the chips must use DC as with every other electronic component.
So does anyone know a reason why ADSL modems seem to be one of the few devices using an AC-AC power supply? Just the preference of some reference design? To discourage the use of crappy switching power supplies with low switching frequencies application-notes. digchip.com/003/3-4102.pdf ? Or was what I read before right and there's some component that uses or works better with AC (and if so what?)?
Nil Einne ( talk) 02:44, 11 February 2013 (UTC)
How to use a PC/laptop to read, write to, and delete data stored in an Android phone's internal (and memory card) storage {just like a USB flash drive}? Czech is Cyrillized ( talk) 03:45, 11 February 2013 (UTC)
which is the first computer operating system and developed by whom? — Preceding unsigned comment added by Anil Golakiya ( talk • contribs) 07:06, 11 February 2013 (UTC)
How large is all the data held by Wikimedia? Are we talking terabytes, petabytes, or exabytes? -- Ypnypn ( talk) 18:32, 11 February 2013 (UTC)
Is it possible with the right cooling setup to over clock my Intel Xeon Processor to 10 GHZ? I currently have it at close to 6 GHZ but is 10 possible? Andrew Wiggin ( talk) 21:47, 11 February 2013 (UTC)
Hi all, I'm working on a simple app (or at least it started out that way) and I am having trouble working out the "right" relationship among classes. File management will be simple enough (at least for the user) but I now have different classes for: "User Account", "Textbook", "File". The File class manages the filesystem, while the others have an obvious meaning. The current setup (not too late to change) has File doing the real work, since the plan is to use it to store/ retrieve. The others are basically data classes, but no file will exist outside of a user account, and there will basically be no sharing between different users. How should these classes interact, and also, can anyone point me to good websites that discuss OO design by example, showing do's and don'ts?? I don't have time to read textbooks on this sort of thing, since I'm only solving a relatively small-scale problem, and no one else is likely to use these classes, but I do want to read some guidance. Something like this would be ideal, but with actual examples that walk you through the things people have done wrong. IBE ( talk) 22:24, 11 February 2013 (UTC)
Thanks to you both. Briefly, the app involves a few trendy extras, but is mostly a souped-up practice journal. You don't load any textbooks (this could change later); you enter the summary details of a textbook, and mark the problems you have done etc. The most complex class (in terms of features) is the "problem/ subproblem" class, but that goes in an obvious enough place, and I'm not exactly confused about it. Yes, a textbook counts as a file, but my point is that a file object seems to make sense for handling loading and saving functions. The reason for having a separate class is to manage Apple's Model–view–controller architecture.
The Controller, called eg. IBE_ViewController, has member data
IBE_View * thisIsTheDisplay; // and IBE_Data * thisIsAllMyData
(the last object is more like several similar objects, but the View is one object). For the Data to talk to the View, you define a protocol, which confused me for the longest time. Some particular class of IBE_Data will name itself as the data source of the View. The View, in turn, declares a "protocol" called IBE_ViewDataSource. The protocol is just a list of methods, nothing more, and they are named (declared) but not defined by the View. The View also declares a member variable which is of type "<IBE_ViewDataSource>", ie. essentially a made up pseudo-type of variable. The declaration goes like this:
@property (some compiler instructions) id <IBE_ViewDataSource> theDataSourceForTheDisplay;
Anything you assign to this must be of a class that implements the protocol, or in other words, that defines the methods declared by the protocol. Example methods would be "returnTheWholeDataArray" or "returnJustTheNumberOfObjectsInTheDataArray". Now the last thing is that the View Controller will assign a Data object to the variable "theDataSourceForTheDisplay", ie. something like
self->thisIsTheDisplay->theDataSourceForTheDisplay = thisIsAllMyData;
This is typically done at startup, since the View Controller is close enough (in spirit) to the "main" function. The trick is that "theDataSourceForTheDisplay" knows about "thisIsAllMyData" but doesn't know much about it - it can only access it via the protocol (I think - I'm new to this stuff).
But I don't want a "thisIsAllMyData" - that's too much in one hit. I just want "thisIsMyMainDataObjectForDisplayingStuff". That must include textbook and account information. So I could go defining different classes as all being data sources (there is no limit, I think) but that seems complex, and I think these things are usually kept pretty tight - very few protocols and data classes. Hence the belief that I need a separate file class - I'm trying to think like an object in that the file class is part of a filing system, which handles the records and stuff - like a kind of bureau, rather than the stuff it contains. Dmcq's choice for best advice was in fact what I was thinking of when I posted the question - it is definitely my main concern that I have no real object orientation. Any thoughts? Also, again, if anyone comes across it, if you have a link that goes into the same advice but that gives examples of actual problems and stuffups, that would be fantastic. IBE ( talk) 18:35, 12 February 2013 (UTC)
Computing desk | ||
---|---|---|
< February 10 | << Jan | February | Mar >> | February 12 > |
Welcome to the Wikipedia Computing Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
I want to download Apache Maven, but their website has 18 download links, just for the latest version! Which one do I click? -- Ypnypn ( talk) 01:35, 11 February 2013 (UTC)
apache-maven-3.0.4-bin.zip
. The .md5
and .asc
files are for helping you to feel assured that the mirror (server) you’re downloading from has given you the authentic file and not something else, but if you’re on Microsoft Windows, it’s (comparatively) absurdly involved to utilize either of those, so you may as well just ask how to in another question if you are interested (after all, if you’re on Microsoft Windows, you’re clearly already content downloading random executables with little idea of their authenticity and running them :/ :p). ¦
Reisio (
talk)
02:56, 11 February 2013 (UTC)I was reminded of this while looking for my spare modem recently. A few years back, I noticed all 3 modems I had used a transformer with an AC output, 2 with 9V and one with 18V. It's easy to find ones using similar AC PSUs from a quick search e.g. [1] 15 VAC, [2] 24 VAC, [3] another 9 VAC, [4] unclear VAC.
While many of these are old, and I'm not suggesting all or even most ADSL modems use AC (I'm not sure what does with built in wireless routers use, and obviously ones which supplies solely by USB as well as PCI, PCI express and ones built in to laptops must use DC), it does seem quite a lot to me. Beyond those used by ADSL modems, all the other devices I've used, e.g. network switches, (standalone) wireless routers, USB DVB-S receivers (which generally used an external PSU), DECT bases with digital answering machines, laptops, (also external HDDs, battery chargers, mobile phones but these are even less surprising), always seem to use a DC output PSU. Of hand, the only other device I know of which use an AC adapter are 12V halogens, although the reason here is more that the halogens don't care (and the supplies are usually internally to the device); although I'm sure there are a lot of other devices that do use AC adapters (probably some music equipment?).
When I first noticed after a long time searching I think I found someone suggesting that some component works best with AC but can't find it again and it may have just been a forum. Most of the chips must use DC as with every other electronic component.
So does anyone know a reason why ADSL modems seem to be one of the few devices using an AC-AC power supply? Just the preference of some reference design? To discourage the use of crappy switching power supplies with low switching frequencies application-notes. digchip.com/003/3-4102.pdf ? Or was what I read before right and there's some component that uses or works better with AC (and if so what?)?
Nil Einne ( talk) 02:44, 11 February 2013 (UTC)
How to use a PC/laptop to read, write to, and delete data stored in an Android phone's internal (and memory card) storage {just like a USB flash drive}? Czech is Cyrillized ( talk) 03:45, 11 February 2013 (UTC)
which is the first computer operating system and developed by whom? — Preceding unsigned comment added by Anil Golakiya ( talk • contribs) 07:06, 11 February 2013 (UTC)
How large is all the data held by Wikimedia? Are we talking terabytes, petabytes, or exabytes? -- Ypnypn ( talk) 18:32, 11 February 2013 (UTC)
Is it possible with the right cooling setup to over clock my Intel Xeon Processor to 10 GHZ? I currently have it at close to 6 GHZ but is 10 possible? Andrew Wiggin ( talk) 21:47, 11 February 2013 (UTC)
Hi all, I'm working on a simple app (or at least it started out that way) and I am having trouble working out the "right" relationship among classes. File management will be simple enough (at least for the user) but I now have different classes for: "User Account", "Textbook", "File". The File class manages the filesystem, while the others have an obvious meaning. The current setup (not too late to change) has File doing the real work, since the plan is to use it to store/ retrieve. The others are basically data classes, but no file will exist outside of a user account, and there will basically be no sharing between different users. How should these classes interact, and also, can anyone point me to good websites that discuss OO design by example, showing do's and don'ts?? I don't have time to read textbooks on this sort of thing, since I'm only solving a relatively small-scale problem, and no one else is likely to use these classes, but I do want to read some guidance. Something like this would be ideal, but with actual examples that walk you through the things people have done wrong. IBE ( talk) 22:24, 11 February 2013 (UTC)
Thanks to you both. Briefly, the app involves a few trendy extras, but is mostly a souped-up practice journal. You don't load any textbooks (this could change later); you enter the summary details of a textbook, and mark the problems you have done etc. The most complex class (in terms of features) is the "problem/ subproblem" class, but that goes in an obvious enough place, and I'm not exactly confused about it. Yes, a textbook counts as a file, but my point is that a file object seems to make sense for handling loading and saving functions. The reason for having a separate class is to manage Apple's Model–view–controller architecture.
The Controller, called eg. IBE_ViewController, has member data
IBE_View * thisIsTheDisplay; // and IBE_Data * thisIsAllMyData
(the last object is more like several similar objects, but the View is one object). For the Data to talk to the View, you define a protocol, which confused me for the longest time. Some particular class of IBE_Data will name itself as the data source of the View. The View, in turn, declares a "protocol" called IBE_ViewDataSource. The protocol is just a list of methods, nothing more, and they are named (declared) but not defined by the View. The View also declares a member variable which is of type "<IBE_ViewDataSource>", ie. essentially a made up pseudo-type of variable. The declaration goes like this:
@property (some compiler instructions) id <IBE_ViewDataSource> theDataSourceForTheDisplay;
Anything you assign to this must be of a class that implements the protocol, or in other words, that defines the methods declared by the protocol. Example methods would be "returnTheWholeDataArray" or "returnJustTheNumberOfObjectsInTheDataArray". Now the last thing is that the View Controller will assign a Data object to the variable "theDataSourceForTheDisplay", ie. something like
self->thisIsTheDisplay->theDataSourceForTheDisplay = thisIsAllMyData;
This is typically done at startup, since the View Controller is close enough (in spirit) to the "main" function. The trick is that "theDataSourceForTheDisplay" knows about "thisIsAllMyData" but doesn't know much about it - it can only access it via the protocol (I think - I'm new to this stuff).
But I don't want a "thisIsAllMyData" - that's too much in one hit. I just want "thisIsMyMainDataObjectForDisplayingStuff". That must include textbook and account information. So I could go defining different classes as all being data sources (there is no limit, I think) but that seems complex, and I think these things are usually kept pretty tight - very few protocols and data classes. Hence the belief that I need a separate file class - I'm trying to think like an object in that the file class is part of a filing system, which handles the records and stuff - like a kind of bureau, rather than the stuff it contains. Dmcq's choice for best advice was in fact what I was thinking of when I posted the question - it is definitely my main concern that I have no real object orientation. Any thoughts? Also, again, if anyone comes across it, if you have a link that goes into the same advice but that gives examples of actual problems and stuffups, that would be fantastic. IBE ( talk) 18:35, 12 February 2013 (UTC)