4 ms·

"Move to Applications Folder?" Dev on how he simplified Mac app installation

46 points by adamhowell 17y ago

cesare 17y ago
Simple and elegant.
poutine 17y ago
Cool stuff, much appreciated. I notice that the code contains the use of 'goto' to handle an error condition. Seems clean. Being somewhat of a intermediate programmer I've always read to stay away from 'goto'. Anyone care to comment on the use of it in Objective-C?
- Empact 17y ago
  In this case, he's emulating the effect of an exception in a language which doesn't support them particularly well[1]: logging the exception message and then moving to a "rescue" or "catch" block which does necessary cleanup. This is one of the few uses of goto which I find acceptable, and it's only necessary because these languages lack exceptions. Using goto for normal control flow, or even complex error handling, can be quite the nightmare. Particularly bi-directional gotos. Given the situation though, that it seems he's avoiding exceptions out of habit or performance concern, I'd still use an exception in this case, rather than the goto, to protect myself from probable misuse and unpredictability. [1] according to this http://stackoverflow.com/questions/324284/how-to-throw-an-exception-in-objective-c-cocoa http://stackoverflow.com/questions/324284/how-to-throw-an-ex..., objective-c has exceptions, but they're resource intensive and should be avoided.
praveengeorge 17y ago
Objective C or regular c gotos represent logic jumps which are hard to track by tools and humans.Debugging is difficult when code conditionally jumps around blocks instead of following a flow pattern easily discenible by reading the code. If good code is poetry code that uses gotos are google translations of poetry :-).Technically sound , emotionally funny
sjs 17y ago
AppTrap detects when apps are trashed and asks if the user would like to trash prefs as well. Very nice solution, way better than AppZapper. http://onnati.net/apptrap/ http://onnati.net/apptrap/ Don't see whey we can't write a project that solves this problem on a general level with a similar method. When a .app appears in specified folders ask to move it to an applications folder. Watched folders default to ~/Desktop and ~/Downloads and the app folder defaults to /Applications.
- pclark 17y ago
  Why would you want to trash prefs? So if in 3 months I re-download the software I have to re-configure it?
derefr 17y ago
But to get back to the conversation that prompted this thought, the same thing could be done with a .dmg; instead of requesting to move itself when a program finds itself unzipped in ~/Downloads, a program could prompt to copy itself to the Applications folder and relaunch from there if it finds itself running from within its disk image. To imagine the dialog, the buttons would be "Copy" (default), "Copy, then Eject and Trash this Image" (for convenience), and "Run from Here" (or perhaps not—there's no really good reason to include it.) You don't have to include the decision between "Copy and Run" or "Just Copy" because the program is already "running" (from the user's perspective); they double-clicked it, didn't they? But because they see the program as "running" from inside the image, they might try to launch the program again from within the .dmg after it had already been copied (if they didn't choose the Trash Image option.) Thus, the program should probably check for a copy of itself in /Applications and exec(3) it if it exists and is the same version, to avoid the lag of re-installing on every start. Though, since you want to kindly escort the users away from the .dmg, it might be better to present another dialog with the options "Run from /Applications" and "Copy Again" (to overwrite the old app—in case of a bad install or somesuch), giving them a small speedbump and a hint about where to find their app. The we-already-did-this dialog could even offer to automatically add an alias of the app to the Desktop or the Dock, "so you won't have to see this again."
- ugh 17y ago
  As your long elaboration demonstrated, disk images are a crappy way to deliver software. Don’t do it.
  - riffic 17y ago
    I'd rather get a .dmg than a .zip with an executable in it. most of the good ones have a "drag to applications folder" shortcut inside of them inside anyways so I don't see the problem with that particular convention.
    - ugh 17y ago
      You are used to it. So am I. If you use a stupid design often enough you become immune to its failings. The concept of disk images is needlessly complex, confusing and way too abstract. You download a file that is a image of a disk, you have to mount that file, you have to drag the contained app to wherever you put your apps and then unmount the disk image. Can’t you see the craziness of this approach? On a Mac your app is a single file (it isn’t, but behaves that way) you can drag anywhere and if you don’t like it anymore you trash it. Delivering your app with a .dmg breaks this simple model. Suddenly this app you see sitting there must be first dragged somewhere before you can use it (and you don‘t even get a warning if you don’t). And you have to handle a completely virtual disk image as if it were some real disk. Crazy.

46 points by adamhowell 17y ago

Simple and elegant.

Cool stuff, much appreciated. I notice that the code contains the use of 'goto' to handle an error condition. Seems clean. Being somewhat of a intermediate programmer I've always read to stay away from 'goto'. Anyone care to comment on the use of it in Objective-C?

Empact 17y ago
In this case, he's emulating the effect of an exception in a language which doesn't support them particularly well[1]: logging the exception message and then moving to a "rescue" or "catch" block which does necessary cleanup. This is one of the few uses of goto which I find acceptable, and it's only necessary because these languages lack exceptions. Using goto for normal control flow, or even complex error handling, can be quite the nightmare. Particularly bi-directional gotos. Given the situation though, that it seems he's avoiding exceptions out of habit or performance concern, I'd still use an exception in this case, rather than the goto, to protect myself from probable misuse and unpredictability. [1] according to this http://stackoverflow.com/questions/324284/how-to-throw-an-exception-in-objective-c-cocoa http://stackoverflow.com/questions/324284/how-to-throw-an-ex..., objective-c has exceptions, but they're resource intensive and should be avoided.

praveengeorge 17y ago

Objective C or regular c gotos represent logic jumps which are hard to track by tools and humans.Debugging is difficult when code conditionally jumps around blocks instead of following a flow pattern easily discenible by reading the code. If good code is poetry code that uses gotos are google translations of poetry :-).Technically sound , emotionally funny

sjs 17y ago

AppTrap detects when apps are trashed and asks if the user would like to trash prefs as well. Very nice solution, way better than AppZapper. http://onnati.net/apptrap/ http://onnati.net/apptrap/ Don't see whey we can't write a project that solves this problem on a general level with a similar method. When a .app appears in specified folders ask to move it to an applications folder. Watched folders default to ~/Desktop and ~/Downloads and the app folder defaults to /Applications.

pclark 17y ago
Why would you want to trash prefs? So if in 3 months I re-download the software I have to re-configure it?

derefr 17y ago

But to get back to the conversation that prompted this thought, the same thing could be done with a .dmg; instead of requesting to move itself when a program finds itself unzipped in ~/Downloads, a program could prompt to copy itself to the Applications folder and relaunch from there if it finds itself running from within its disk image. To imagine the dialog, the buttons would be "Copy" (default), "Copy, then Eject and Trash this Image" (for convenience), and "Run from Here" (or perhaps not—there's no really good reason to include it.) You don't have to include the decision between "Copy and Run" or "Just Copy" because the program is already "running" (from the user's perspective); they double-clicked it, didn't they? But because they see the program as "running" from inside the image, they might try to launch the program again from within the .dmg after it had already been copied (if they didn't choose the Trash Image option.) Thus, the program should probably check for a copy of itself in /Applications and exec(3) it if it exists and is the same version, to avoid the lag of re-installing on every start. Though, since you want to kindly escort the users away from the .dmg, it might be better to present another dialog with the options "Run from /Applications" and "Copy Again" (to overwrite the old app—in case of a bad install or somesuch), giving them a small speedbump and a hint about where to find their app. The we-already-did-this dialog could even offer to automatically add an alias of the app to the Desktop or the Dock, "so you won't have to see this again."

ugh 17y ago
As your long elaboration demonstrated, disk images are a crappy way to deliver software. Don’t do it.
- riffic 17y ago
  I'd rather get a .dmg than a .zip with an executable in it. most of the good ones have a "drag to applications folder" shortcut inside of them inside anyways so I don't see the problem with that particular convention.
  - ugh 17y ago
    You are used to it. So am I. If you use a stupid design often enough you become immune to its failings. The concept of disk images is needlessly complex, confusing and way too abstract. You download a file that is a image of a disk, you have to mount that file, you have to drag the contained app to wherever you put your apps and then unmount the disk image. Can’t you see the craziness of this approach? On a Mac your app is a single file (it isn’t, but behaves that way) you can drag anywhere and if you don’t like it anymore you trash it. Delivering your app with a .dmg breaks this simple model. Suddenly this app you see sitting there must be first dragged somewhere before you can use it (and you don‘t even get a warning if you don’t). And you have to handle a completely virtual disk image as if it were some real disk. Crazy.