June 2008 - Pro-apps-dev - lists.apple.com

Re: FCP FxPlug load order - how do I control?
by Paul Schneider 26 Jun '08

26 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Hi Pierre, [[MyFunClass alloc] init]; - Paul On Jun 26, 2008, at 1:27 PM, Pierre Jasmin wrote: Side Note: Pierre _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/pschneider%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… I keep hearing it's an Objective C issue with dynamic libraries. That does not sound right to me. The Objective-C runtime maintains a flat registry of all the classes defined in a process. It currently makes no distinction as to which library implements the classes. Classes are added to the registry the first time they are used. So for example, if your plugin calls: "MyFunClass" is now loaded into the global application namespace. Any code anywhere in the application can now use MyFunClass. If another library has already defined a "MyFunClass" class, then your plugin will end up using that class instead. C and C++ symbols can be restricted to individual libraries with the appropriate compiler switches, as Pete so helpfully pointed out. Obj- C classes are different; since they are not resolved at link time, but at run time, the compiler can't help you. The language's runtime would have to be modified to support per-library namespaces. Otherwise isn't there a risk (aside secutiry) if symbols get loaded in global space, that I name a function the same as you and inadvertently override it in the exec. Yes, this is a concern. Many Objective-C mavens would consider this a feature; you are free to extend or modify all classes, even those you didn't write. It's an intriguing feature in a modular application; it can cause trouble in an app that can load an arbitrary number of third- party plugins that come from various vendors and source bases. I keep hearing it's an Objective C issue with dynamic libraries. That does not sound right to me. Since I know nothing about ObjectiveC (could not even develop a stand-alone to test what I am saying), can I ask if it isn't the issue itself in Apple implementation of dlopen (or whatever you use to load) - OR simply the arguments passed to dlopen? Don't you just dlsym() the entry points of the API (RTLD_LOCAL or something)? Otherwise isn't there a risk (aside secutiry) if symbols get loaded in global space, that I name a function the same as you and inadvertently override it in the exec. This email sent to pschneider(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Paul Miller 26 Jun '08

26 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com User-agent: Thunderbird 2.0.0.14 (Windows/20080421) Side Note: -- Paul Miller | paul(a)fxtech.com | www.fxtech.com | Got Tivo? _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… Pierre Jasmin wrote: I keep hearing it's an Objective C issue with dynamic libraries. That does not sound right to me. Since I know nothing about ObjectiveC (could not even develop a stand-alone to test what I am saying), can I ask if it isn't the issue itself in Apple implementation of dlopen (or whatever you use to load) - OR simply the arguments passed to dlopen? Don't you just dlsym() the entry points of the API (RTLD_LOCAL or something)? Otherwise isn't there a risk (aside secutiry) if symbols get loaded in global space, that I name a function the same as you and inadvertently override it in the exec. That does seem to be the case here. I don't know if it's ObjectiveC that's causing it, or if it just happens with pure C++ (name mangling or something). Incidentally, the compiler-switches Peter recommended solved my problem with the new plugin, and fortunately I didn't have to go back and touch v1. This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Pierre Jasmin 26 Jun '08

26 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Organization: RE:Vision Effects User-agent: Thunderbird 2.0.0.14 (Windows/20080421) Side Note: Pierre _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… I keep hearing it's an Objective C issue with dynamic libraries. That does not sound right to me. Since I know nothing about ObjectiveC (could not even develop a stand-alone to test what I am saying), can I ask if it isn't the issue itself in Apple implementation of dlopen (or whatever you use to load) - OR simply the arguments passed to dlopen? Don't you just dlsym() the entry points of the API (RTLD_LOCAL or something)? Otherwise isn't there a risk (aside secutiry) if symbols get loaded in global space, that I name a function the same as you and inadvertently override it in the exec. This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Peter Litwinowicz 26 Jun '08

26 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Thread-index: AcjXOHt9ukBPBEMrEd2N/AAfWzOy/A== Thread-topic: FCP FxPlug load order - how do I control? User-agent: Microsoft-Entourage/11.4.0.080122 > Peter Litwinowicz wrote: >> >>> I should have been more clear. They are independent plugins that happen >>> to have some C++ classes in each that are named the same. >>> >>> Say I have a C++ class GlobalStuff in each one, and it's declared >>> statically. The second one to load is calling into the methods of the >>> instance in v1, even though they are declared statically. This doesn't >>> happen with similar code in other hosts. >> >> To Paul M., >> >> Hopefully you are using GCC 4 or later. I found the info below on the >> web here http://gcc.gnu.org/wiki/Visibility and was instrumental in >> getting our FxPlugs working properly (because we ran into what you are >> running into). It¹s not a host problem. It¹s a C/C++ compiled code >> loading problem in Objective-C hosts. Blame the compiler/linker >> writers! However, there IS an easy fix. > > Thanks Pete - I knew there would be something like this in there. I'm > using Xcode, so I assume I can just set those extra command-line > switches you mentioned on the "Other linker flags" setting. Except that I have it in my "other C flags" entry (and hence "other C++ Flags" entry), not "Other linker flags" Perhaps it gets passed to the linker as well, but I believe you need it at compile time too? Dunno. Just know what I have. Also, hopefully you are using GCC4 (with Xcode) or later. Gcc 3.3 does not support the hidden flags. Pete _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Paul Miller 26 Jun '08

26 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com User-agent: Thunderbird 2.0.0.14 (Windows/20080421) I should have been more clear. They are independent plugins that happen to have some C++ classes in each that are named the same. Say I have a C++ class GlobalStuff in each one, and it's declared statically. The second one to load is calling into the methods of the instance in v1, even though they are declared statically. This doesn't happen with similar code in other hosts. To Paul M., Cheers. -- Paul Miller | paul(a)fxtech.com | www.fxtech.com | Got Tivo? _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… Peter Litwinowicz wrote: Hopefully you are using GCC 4 or later. I found the info below on the web here http://gcc.gnu.org/wiki/Visibility and was instrumental in getting our FxPlugs working properly (because we ran into what you are running into). It’s not a host problem. It’s a C/C++ compiled code loading problem in Objective-C hosts. Blame the compiler/linker writers! However, there IS an easy fix. Thanks Pete - I knew there would be something like this in there. I'm using Xcode, so I assume I can just set those extra command-line switches you mentioned on the "Other linker flags" setting. I had just read up on the __attribute__ visibility thingy last week, but wasn't sure of the best way to enable it. This email sent to site_archiver(a)lists.apple.com

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About add menu item in fcp
by Luly 26 Jun '08

26 Jun '08

site_archiver(a)lists.apple.com Delivered-To: Pro-apps-dev(a)lists.apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Peter Litwinowicz 25 Jun '08

25 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Thread-index: AcjXEsEm/9tjnkMFEd2N/AAfWzOy/A== Thread-topic: FCP FxPlug load order - how do I control? User-agent: Microsoft-Entourage/11.4.0.080122 _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Paul Schneider 25 Jun '08

25 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Ah, these are C++ classes. Are your static instances defined like this? shared.h: class MyStuff { static MyStuff* theStuff; }; or like this? notshared.cpp: static MyStuff* theStuff; This might shed some light on your problem as well... http://developer.apple.com/documentation/DeveloperTools/Conceptual/CppRunti… - Paul On Jun 25, 2008, at 5:44 PM, Paul Miller wrote: -- Paul Miller | paul(a)fxtech.com | www.fxtech.com | Got Tivo? _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/pschneider%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… Say I have a C++ class GlobalStuff in each one, and it's declared statically. The second one to load is calling into the methods of the instance in v1, even though they are declared statically. This doesn't happen with similar code in other hosts. The first one might not work the way you want with the default compiler settings. Paul Schneider wrote: Hi Paul, FWIW - I've got some classes in both, and the second one to load is calling into the code from the first one to load. Is there a way to keep each one from seeing the classes/code in the other? there's no way to prevent this in Objective C at the moment (google for "flat namespace"). Defining common classes in one plugin and having other plugins counting on that plugin to be loaded is probably asking for trouble. The two ways to get around this problem are: 1) if you can, put all of your plugin classes into a single bundle. We use this technique ourselves; I can explain how it works if you'd like. 2) if you can't do #1, put the common classes in a shared framework, and have both plugins link to the framework. Really, the only reason not to do #1 is if the two plugins are two separate products, sold separately, and the user could legitimately have one installed but not the other. But it sounds like if that were the case, what you're doing wouldn't work (plugin B depends on plugin A, right?). I should have been more clear. They are independent plugins that happen to have some C++ classes in each that are named the same. Say I have a C++ class GlobalStuff in each one, and it's declared statically. The second one to load is calling into the methods of the instance in v1, even though they are declared statically. This doesn't happen with similar code in other hosts. This email sent to pschneider(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Paul Miller 25 Jun '08

25 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com User-agent: Thunderbird 2.0.0.14 (Windows/20080421) Hi Paul, The two ways to get around this problem are: -- Paul Miller | paul(a)fxtech.com | www.fxtech.com | Got Tivo? _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… Paul Schneider wrote: FWIW - I've got some classes in both, and the second one to load is calling into the code from the first one to load. Is there a way to keep each one from seeing the classes/code in the other? there's no way to prevent this in Objective C at the moment (google for "flat namespace"). Defining common classes in one plugin and having other plugins counting on that plugin to be loaded is probably asking for trouble. 1) if you can, put all of your plugin classes into a single bundle. We use this technique ourselves; I can explain how it works if you'd like. 2) if you can't do #1, put the common classes in a shared framework, and have both plugins link to the framework. Really, the only reason not to do #1 is if the two plugins are two separate products, sold separately, and the user could legitimately have one installed but not the other. But it sounds like if that were the case, what you're doing wouldn't work (plugin B depends on plugin A, right?). I should have been more clear. They are independent plugins that happen to have some C++ classes in each that are named the same. Say I have a C++ class GlobalStuff in each one, and it's declared statically. The second one to load is calling into the methods of the instance in v1, even though they are declared statically. This doesn't happen with similar code in other hosts. This email sent to site_archiver(a)lists.apple.com

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Re: FCP FxPlug load order - how do I control?
by Paul Schneider 25 Jun '08

25 Jun '08

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Hi Paul, The two ways to get around this problem are: - Paul On Jun 25, 2008, at 5:30 PM, Paul Miller wrote: -- Paul Miller | paul(a)fxtech.com | www.fxtech.com | Got Tivo? _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/pschneider%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… FWIW - I've got some classes in both, and the second one to load is calling into the code from the first one to load. Is there a way to keep each one from seeing the classes/code in the other? there's no way to prevent this in Objective C at the moment (google for "flat namespace"). Defining common classes in one plugin and having other plugins counting on that plugin to be loaded is probably asking for trouble. 1) if you can, put all of your plugin classes into a single bundle. We use this technique ourselves; I can explain how it works if you'd like. 2) if you can't do #1, put the common classes in a shared framework, and have both plugins link to the framework. Really, the only reason not to do #1 is if the two plugins are two separate products, sold separately, and the user could legitimately have one installed but not the other. But it sounds like if that were the case, what you're doing wouldn't work (plugin B depends on plugin A, right?). Paul Miller wrote: (I know - this is a goofy one). FWIW - I've got some classes in both, and the second one to load is calling into the code from the first one to load. Is there a way to keep each one from seeing the classes/code in the other? This email sent to pschneider(a)apple.com This email sent to site_archiver(a)lists.apple.com

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