Forgive me if there is an extremely simple answer to this question.
I am currently updating a series of .fla files that someone else created. Within one of the symbols is the following code: this.insertMovieClip("symbolName","objectReferenceName",5);
I understand what the code is doing, or rather what it would do normally. It would find a symbol named symbolName in the library, and create an instance of it named objectReferenceName inside this MovieClip.
The problem is that I have searched the library, and I can't find anything named symbolName. It doesn't exist. But somehow, there is a movie clip being called at runtime - the code works. What am I missing here?
The symbol names in the library actually have no effect at run-time—they are simply labels. The identifier that gets used at run-time is set in the Linkage properties for a symbol. You can see this by looking under the AS Linkage column in the library, or right-clicking a symbol and clicking Properties.
In AS2, you assign an identifier to a symbol by checking the "Export for ActionScript" box in the Properties dialog. You can then create an instance of that symbol from ActionScript like this:
attachMovieClip("linkageIdentifier", "reference", depth);
This is probably what your insertMovieClip function is doing.
Related
I'm using :class: and getting a lot of warnings
WARNING: py:class reference target not found: mypkg.submodule.class.
I can't find anywhere in the documentation what exactly the requirements are for a correct cross-reference.
This is currently an incomplete list of requirements I think there are:
The module of the object needs to be importable
The object needs to exist inside of the module
The object needs to be documented somewhere else in the build with a :py:class::, :py:func:: or similar directive
This directive can be generated by the autodoc extension, in which case the object needs to have a docstring associated to it.
For something to be cross-referenced it has to first be "declared".
The Python domain (name py) provides the following directives for module declarations:
There are 2 cases to consider:
domain directives (.. domain:directive_name::) and
roles (:domain:role_name:).
The case of :class: you specify is actually the shortened syntax of writing the role :py:class: not to be confused with the directive declaration .. py:class::.
This directive can be generated by the autodoc extension, in which case the object needs to have a docstring associated to it.
The directive declarations are done implicitly by autodoc, but for objects without docstrings to be declared by autodoc you must use :undoc-members: option with the autodoc directives.
Members without docstrings will be left out, unless you give the undoc-members flag option:
.. automodule:: noodle
:members:
:undoc-members:
One effect of declaring an object is that it is inserted in the index. So you can check the index to make sure it has been declared and inserted. (However note that labels used in referencing arbitrary locations are not inserted in the index.)
I have a fork of the JavaScriptCore framework, where I have added a function of my own, which is exported. The framework compiles just find. Running nm on the framework reveals that the function (JSContextCreateBacktrace_unsafe) is indeed exported:
Leo-Natans-Wix-MPB:JavaScriptCore.framework lnatan$ nm -gU JavaScriptCore.framework/JavaScriptCore | grep JSContextCreateBacktrace
00000000004cb860 T _JSContextCreateBacktrace
00000000004cba10 T _JSContextCreateBacktrace_unsafe
However, I am unable to obtain the pointer of that function using CFBundleGetFunctionPointerForName or dlsym; both return NULL. At first, I used dlopen to open my framework, then tried using CFBundleCreate and then CFBundleGetFunctionPointerForName but that also returns NULL.
What could cause this?
Update
Something fishy is going on. I renamed one of the JSC functions, and nm reflects this. However, dlsym is still able to find the function with the original name, rather than the renamed.
It's hard to track this down since it's highly dependent on your specific environment and circumstances, but it is very likely you're running into this issue because the system image has already been loaded and you haven't changed the name of the framework.
If you look at the source code for dlopen in dyld/dyldAPIS.cpp:1458, you'll notice the context passed to dyld is configured with matchByInstallName = true. This context is then passed to load which executes the various stages necessary for image loading. There are a few phases worth noting:
loadPhase2 in dyld/dyld.cpp:2896 extracts the ending of the framework path and searches for it in the search path
loadPhase5check in dyld/dyld:2712 iterates over all loaded images and determines if any of them have a matching install name, and if one does, it returns that instead of loading a new one.
loadPhase5load in dyld/dyld:2601 finally loads the image if it wasn't loaded/found by any earlier steps. (It's worth noting loadPhase5check is executed first, since image loading is a two pass process.)
Given all of the above, I'd try renaming your framework to something besides JavaScriptCore.framework. Depending on the install name of both the system framework and your framework, I'd also recommend changing the install name. (There are plenty of blog articles and StackOverflow posts that document how to do this using install_name_tool -id.)
Here is a quotation from the other post:
I'm working in a iOS project that includes a static library created by another company. The library include an old version of AFNeworking and I don't have any source files.
Now i need to use a more recent (and less bugged) version of afneworking, but i cannot include the same class twice in the project (of course) because all the "duplicate symbols"
My problem is that I'm preparing an iOS framework and I want to avoid this kind of situation in the future. I'm not talking about AFNetworking, but other quite popular iOS framework. In addition I applied some custom changes in the original framework code.
The one way to avoid "duplicate symbols" and "Class X is implemented in both Y and Z. One of the two will be used" that comes to my mind is to add some prefix to the original framework classes, but is this the right solution?
UPDATE 1:
I tried to apply John's solution but no joy. I have created a simplified project (here is the link to the repo) with two classes FrameworkClass which is present in framework target only, and SharedClass which is present in both framework and application targets, so maybe you can see if I'm doing something wrong. After application did launch I'm still getting:
objc[96426]: Class SharedClass is implemented in both .../TestFramework.framework/TestFramework and .../SymbolsVisibilityTest.app/SymbolsVisibilityTest. One of the two will be used. Which one is undefined
UPDATE 2:
Here is my output from nm based on the provided sample project's framework-output:
0000000000007e14 t -[FrameworkClass doFramework]
0000000000007e68 t -[SharedClass doShared]
U _NSLog
U _NSStringFromSelector
00000000000081f0 s _OBJC_CLASS_$_FrameworkClass
U _OBJC_CLASS_$_NSObject
0000000000008240 s _OBJC_CLASS_$_SharedClass
00000000000081c8 s _OBJC_METACLASS_$_FrameworkClass
U _OBJC_METACLASS_$_NSObject
0000000000008218 s _OBJC_METACLASS_$_SharedClass
0000000000007fb0 s _TestFrameworkVersionNumber
0000000000007f70 s _TestFrameworkVersionString
U ___CFConstantStringClassReference
U __objc_empty_cache
U _objc_release
U _objc_retainAutoreleasedReturnValue
U dyld_stub_binder`
UPDATE 3:
I did manage to "hide" SharedClass symbols by applying the solution by #bleater and my output from nm is now:
U _NSLog
U _NSStringFromSelector
00001114 S _OBJC_CLASS_$_FrameworkClass
U _OBJC_CLASS_$_NSObject
00001100 S _OBJC_METACLASS_$_FrameworkClass
U _OBJC_METACLASS_$_NSObject
U ___CFConstantStringClassReference
U __objc_empty_cache
U _objc_release
U _objc_retainAutoreleasedReturnValue
U dyld_stub_binder`
But I'm still getting double implementation warning in Xcode.
You should limit the visibility of symbols in any framework or library you are developing. Set the default visibility to hidden, and then explicitly mark all the functions in the public interface as visible.
This avoids all the problems you have described. You can then include any version of any public library (AFNetworking, SQLite, etc.), without fear of future conflict because anything linking to your framework or library won't be able to "see" those symbols.
To set the default visibility to hidden you can go into the project settings and set "Symbols Hidden by Default" to YES. It is set to NO unless you change it.
There are at least a couple of ways to mark the symbols from your public interface as "Visible". One is by using an exports file, another is to go through and explicitly mark certain functions as visible:
#define EXPORT __attribute__((visibility("default")))
EXPORT int MyFunction1();
The define is obviously just for convenience. You define EXPORT once and then just add EXPORT to all of your public symbols.
You can find official apple documentation on this here:
Runtime Environment Programming Guide
Update:
I took a look at your sample project, and it looks like I pointed you in the wrong direction. It appears that you can only truly hide C and C++ symbols. So if your were having this problem with a C lib (like sqlite), setting the default visibility to hidden would work. It looks like the nature of the Objective C runtime prevents you from truly making the symbols invisible. You CAN mark the visibility on these symbols, but with Objective-C it appears that is just a way to have the linker enforce what you should or shouldn't be able to use from the library (while still leaving them visible).
So if you redefine a Objective-C symbol in different compilation unit with the same name (by perhaps compiling in a new version of a popular open source library), then you will still have a conflict.
I think your only solution at this point is to do what you first suggested and prefix the symbols you are including into your framework with a unique identifier. It isn't a very elegant solution, but with the limits of the objective C runtime I believe it is probably the best solution available.
So the blog post by Kamil Burczyk was a good starting point, thanks for the hint Michał Ciuba! It has covered most of the symbols, but it didn't cope with categories and class clusters. You can see what category methods are still exposed without any change by invoking nm with parameter list sth like:
nm MyLibrary | grep \( | grep -v "\[LIBRARYPREFIX" | grep -v \(MyLibrary | grep -v ") prefix_"
When it comes to categories we have 3 groups of categories, and they all require a specific, different approach:
Categories on classes that has been renamed by NamespacedDependencies.h
Categories on classes not renamed by NamespacedDependencies.h
Categories on class clusters like NSString, NSArray...
Ad 1.
Everything is ok - class name will be prefixed so category will exist on prefixed sumbol in object file
Ad 2.
This problem occours whenever inside of the dependency we have category on a class like NSObject. It would be exposed without any change in object file, thus would cause a conflict. My approach was to internally rename NSObject to PREFIX_NSObject, this ofcourse requires me also to create and add the PREFIX_NSObject class implementation to the project (empty implementation, just a subclass of original NSObject)
#import "PREFIX_NSObject.h"
#ifndef NSValueTransformer
#define NSValueTransformer __NS_SYMBOL(NSObject)
#endif
Ad 3.
We cannot apply Ad 2. approach here. Actual objects created by let's say PREFIX_NSArray class methods are still of type that wont derive from my presumable PREFIX_NSArray class, so this doesn't make sense as category methods defined on PREFIX_NSArray won't be visible on NSArray derived objects. I ended up by manually prefixing methods of those categories in source code.
It's kind of crazy workflow, but at least gives warranty that everything will be 'invisible' and won't cause a conflict.
It's always good idea to run nm to check if all category symbols are hidden:
nm MyLibrary | grep \( | grep -v "\[LIBRARYPREFIX" | grep -v \(MyLibrary | grep -v ") prefix_"
I have a doubt about indicating a path in makefile and I'd like to have a clarification.
Suppose my structure is made this way:
/home/machinename/softwarefolder/mainfolder
--------------------------------------------> /subfolder1
--------------------------------------------> /subfolder2
This means that both subfolder1 and subfolder2 are at the same nesting level in /mainfolder.
Now I'm compiling something inside subfolder 2 (this means that I cd to that folder) that uses a configure file with a macro pointing to a path that, in my case, it's in subfolder1.
This configure file used by the program in subfolder2 to compile is generated automatically by the program itself after running ./configure
The automatically generated configure file has the macro defined this way
MACRO = ../subfolder1
Do the two dots (..) indicate, as in the cd command, "go back one step" (and, therefor, the configure file is pointing to the right folder)?
If the answer to the first question is "no", then why substituting the aforementioned macro with
MACRO = /home/machinename/softwarefolder/mainfolder/subfolder1
generates a "missing separator" error in compile-time?
Sorry for the probably trivial question and thanks for the help!
Make doesn't interpret the content of variables in any way, for the most part. The question of how the .. will be interpreted depends entirely on where the variable is used. If it's used in a place where a path like ../subfolder1 makes sense, then that's how it will be interpreted. If not, not.
Since you don't show how $(MACRO) is used, we can't help. But in general the answer to your question is "yes, it means go up to the parent directory".
As for your second question, there is no way I can envision that changing just that one line will result in a "missing separator" error. Maybe your editor "helpfully" made other changes to the file such as removing TABs and substituting spaces, or adding TABs? TAB characters are special in makefiles.
If you want help with the second question you must provide (a) the exact error you received (cut and paste is best), and (b) the exact text of the rule in the makefile at the line number specified in the error message.
I'm trying to get an auto generated list of symbols in my latex project. Here is the macro that I have so far...
\newcommand{\addsymbol}[3]{%
\symboldisplay{#1}{#2}\\%
\setelem{#3}{#1}
}
\newcommand{\symboldisplay}[2]{%
$#1$ \parbox{5in}{\dotfill #2}%
}
\def\setelem#1{\expandafter\def\csname myarray(#1)\endcsname}
\def\dispsymbol#1{\csname myarray(#1)\endcsname}
I then include my list of symbols like so
\begin{listofsymbols}
\input{symbols}
\end{listofsymbols}
where the symbols.tex file is
\addsymbol{n}{Number of sample points}{num_points}
\addsymbol{f_s}{Sampling frequency}{samp_frequency}
I can then get my symbol by label like so: \dispsymbol{num_points} -- this displays n in this case.
This works all find and dandy... when I am calling \dispsymbol in the same chapter (the List of Symbols chapter) as the \addsymbol def. When I try to get the label for the symbol in another chapter nothing seems to work.
Could anyone help me, or suggest a package that will do what I am looking for?
The thing is that
\begin{listofsymbols}
\end{listofsymbols}
is the scope and any macro is lost after this group. You should define the global macros.
Replace the following
\def\setelem#1{\expandafter\def\csname myarray(#1)\endcsname}
with
\def\setelem#1{\expandafter\gdef\csname myarray(#1)\endcsname}
To automatically generate a list of symbols you can use the nomencl package, or for more complex documents that requires also glossaries or lists of acronyms, the glossaries package.
Check the examples in the documentation ;)