cmake: qt resources inside a module - qt

i have this tree structure:
repository/modules/module1
repository/modules/module2
repository/modules/module..
repository/apps/application1
repository/apps/application2
repository/apps/application..
where the applications are using some modules.
now, I'd like to put some resources inside a module (like a very colorfull icons inside a widget used by several applications) but.. something gets wrong.
inside the module CMakeLists.txt if I use only:
set(${MODULE_NAME}_RCS
colors.qrc
)
...
qt4_add_resources (${MODULE_NAME}_RHEADERS ${${MODULE_NAME}_RCS})
no qrc_colors.cxx are created anywhere. so I've tried to add:
ADD_EXECUTABLE (${MODULE_NAME}
${${MODULE_NAME}_RHEADERS}
)
but.. I get this weird error:
CMake Error at repo/modules/ColorModule/CMakeLists.txt:51 (ADD_EXECUTABLE):
add_executable cannot create target "ColorModule" because another
target with the same name already exists. The existing target is a static
library created in source directory
"repo/modules/ColorModule". See documentation for
policy CMP0002 for more details.
(I've changed the path of the error of course)
so.. don't know what to think because i'm new both to cmake and qt..
what can i try?
EDIT:
if I add the ${MODULE_NAME}_RHEADERS and ${MODULE_NAME}_RCS in the add_library command the qrc_colors.cxx is created BUT it is in repository/modules/module1/built and not copied in the application built directory...

There is at least two errors in your code.
1) It is usually not necessary to use ${MODULE_NAME} everywhere like that, just "MODULE_NAME". You can see that the difference is the raw string vs. variable. It is usually recommended to avoid double variable value dereference if possible.
2) More importantly, you seem to be setting ${MODULE_NAME} in more than one executable place, which is "ColorModule" according to the error output. You should have individual executable names for different binaries.
Also, the resource file focus is a bit of red herring in here. There are several other issues with your project.
You can cmake files as CmakeLists.txt instead of CMakeLists.txt which inherently causes issues on case sensitive systes as my Linux box.
You use Findfoo.cmake, and find_package(foo) for that matter, rather than the usual FindFoo.cmake convention alongside find_package(Foo).
Your FindFoo.cmake is quite odd, and you should probably be rewritten.
Most importantly, you should use config files rather than find modules.
Documentation and examples can be found at these places:
http://www.cmake.org/Wiki/CMake/Tutorials#CMake_Packages
https://projects.kde.org/projects/kde/kdeexamples/repository/revisions/master/show/buildsystem
When you would like use a find module, you need to have that at hand already. That will tell you what to look for, where things are, or if they are not anywhere where necessary. It is not something that you should write. You should just reuse existing ones for those projects that are not using cmake, and hence the find modules are added separately.
It is a bit like putting the treasure map just next to the treasure. Do you understand the irony? :) Once you find the map, you would automatically have the treasure as well. i.e. you would not look for it anymore.

Related

QML Module not found with registered types

I have the following Issue:
In main.qml I get these errors. Although I can use these types perfectly in the code. It looks like it is just an intellisense issue.
These types are registered in main.cpp:
Thse classes are defined in the include folder:
My folder structure looks like this:
Do I have to modify QML_IMPORT_PATH in the pro file? I added src and include folder but it does not work:
QML_IMPORT_PATH += src
QML_IMPORT_PATH += include
The code itself runs fine. It is just an Intellisense issue.
I assume this is simply a Qt Creator bug. Take a look at this one. qmlRegisterSingletonInstance was added to the Qt library in version Qt 5.14. Even though Qt Creator 4.13.3 was built with Qt 5.15.2, the QML code model it uses has apparently still not been updated.
You need to run this code. QtCreator is notorious for flagging errors that don't exist or won't exist. It flags header files for .ui files because you haven't run a build yet so they haven't been generated. Many developers paint their UI files then do a fake build just to generate those files so QtCreator shuts up.
The other thing you need to do is provide the full source code for one of those classes. (I will assume they all have the same issue.)
The example Qt gives here isn't a good one. You should never be able to "new" a Singleton. The constructor should be protected and the Instance() method should construct one and only one if the internal pointer is null.
Do you actually have a method named get() in each of those classes? Does it actually return a pointer? Many return a reference, that is why I'm asking. If we overlook the glaring error of being able to "new" a Singleton, there is one good thing in this example.
QScopedPointer<SingletonTypeExample> example(new SingletonTypeExample);
They used a QScopedPointer to the class.
qmlRegisterSingletonInstance("Qt.example.qobjectSingleton", 1, 0, "MyApi", example.get());
Once you actually build you will have all of the MOC information where it needs to be. This may well make QtCreator happy. Honestly, I've stopped looking at what QtCreator flags anymore because there are so many false alarms.

Forward declaring a class in a UI file

I just wondered if there was a way to forward-declare a class in a Qt UI file. The issue that I have is that I use (the same version of) a same widget in two different projects : a project that uses the widget and an independant project that allows me to do testing with this widget while I'm working on its features.
Now, what happens is that when uic generates the ui_widget.h file, it adds this in it:
#include "widgets/custom_line_edit.h"
That's the include path for one of my promoted widgets. The thing is that the path to this file is not the same on the "real" project, as it should be
#include "modules/this_module/widgets/custom_line_edit.h"
I don't really know what to do not to have to edit my UI file each time to match my "current" project's file organization.
I've found this which was quite satisfying:
It is sometimes necessary to forward declare classes, particularly if code is being written in .ui.h files within Qt Designer. Each forward declaration is listed as it should appear in the generated C++ code.
<forwards>
<forward>class QStringList;</forward>
</forwards>```
But unfortunately this documentation is quite old (Qt 3.3) and the syntax seems not to work anymore - I get an Error 1.
What are my options here?
The issue isn't one of forward declarations. I've never seen that "forward" mechanism in a UI file, but even it still works somehow, all that it does is put "class QStringList;" (or whatever) in the include file that uic generates. If you look at those include files, they will have "new SomeWidget ()" statements, and you can't create an object without its full declaration, so a forward declaration for something the UI file creates isn't helpful.
The UI definition needs the include file where the widget is defined for exactly that reason. It has to include the class definition in the file generated from uic, and the relationship between where the files reside is going to have to be consistent.
What I would do to solve this is put the widget(s) in a library, and then reference the library from my main application and my test application. Then the uic generation happens within the library, not the applications, and within the library, the relative locations of the files will remain constant. The applications don't need access to the .ui file nor the generated include file, so how the application source files are laid out in folders won't matter.
I don't see any other way to do this.

Ada `Gprbuild` Shorter File Names, Organized into Directories

Over the past few weeks I have been getting into Ada, for various different reasons. But there is no doubt that information regarding my personal reasons as to why I'm using Ada is out of scope for this question.
As of the other day I started using the gprbuild command that comes with the Windows version of GNAT, in order to get the benefits of a system for managing my applications in a project-related manner. That is, being able to define certain attributes on a per-project basis, rather than manually setting up the compile-phase myself.
Currently when naming my files, their names are based off of what seems to be a standard for the grpbuild, although I could very much be wrong. For periods (in the package structure), a - is put in the name of the file, for underscores, an _ is put accordingly. As such, a package by the name App.Test.File_Utils would have a file name of app-test-file_utils: .ads and .adb accordingly.
In the .gpr project file I have specified:
for Source_Dirs use ("app/src/**");
so that I am allowed to use multiple directories for storing my files, rather than needing to have them all in the same directory.
The Problem
The problem that arises, however, is that file names tend to get very long. As I am already putting the files in a directory based on the package name contained by the file, I was wondering if there is a way to somehow make the compiler understand that the package name can be retrieved from the file's directory name.
That is, rather than having to name the App.Test.File_Utils' file name app-test-file_utils, I would like it to reside under the app/test directory by the name file_utils.
Is this doable, or will I be stuck with the horrors of eventually having to name my files along the lines of: app-test-some-then-one-has-more_files-another_package-knew-test-more-important_package.ads? Granted, I have not missed something about how an Ada application should actually be structured.
What I have tried
I tried looking for answers in the package Naming configuration of the gpr files in the documentation, but to no avail. Furthermore I have been browsing the web for information, but decided it might be better to get help through Stackoverflow, so that other people who might struggle with this problem in the future (granted it is a problem in the first place) might also get help.
Any pointers in the right direction would be very helpful!
In the top-secret GNAT documentation there is a description of how to use non-default file names. It's a great deal of effort. You will probably give up, use the default names, and put them all in a single directory.
You can also simplify much of the effort by using GPS and letting it build your project file as you add files to your source directories.

Closure: --namespace Foo does not include Foo.Bar, and related issues

I have a rather big library with a significant set of APIs that I need to expose. In fact, I'd like to expose the whole thing. There is a lot of namespacing going on, like:
FooLibrary.Bar
FooLibrary.Qux.Rumps
FooLibrary.Qux.Scrooge
..
Basically, what I would like to do is make sure that the user can access that whole namespace. I have had a whole bunch of trouble with this, and I'm totally new to closure, so I thought I'd ask for some input.
First, I need closurebuilder.py to send the full list of files to the closure compiler. This doesn't seem supported: --namespace Foo does not include Foo.Bar. --input only allows a single file, not a directory. Nor can I simply send my list of files to the closure compiler directly, because my code is also requiring things like "goog.assers", so I do need the resolver.
In fact, the only solution I can see is having a FooLibrary.ExposeAPI JS file that #require's everything. Surely that can't be right?
This is my main issue.
However, later the closure compiler, with ADVANCED_OPTIMIZATIONS on, will optimize all these names away. Now I can fix that by adding "#export" all over the place, which I am not happy about, but should work. I suppose it would also be valid to use an extern here. Or I could simply disable advanced optimizations.
What I can't do, apparently, is say "export FooLibrary.*". Wouldn't that make sense?
Finally, for working in source mode, I need to do goog.require() for every namespace I am using. This is merely an inconvenience, though I am mentioning because it sort of related to my trouble above. I would prefer to be able to do:
goog.requireRecursively('FooLibrary')
in order to pull all the child namespaces as well; thus, recreating with a single command the environment that I have when I am using the compiled version of my library.
I feel like I am possibly misunderstanding some things, or how Closure is supposed to be used. I'd be interested in looking at other Closure-based libraries to see how they solve this.
You are discovering that Closure-compiler is built more for the end consumer and not as much for the library author.
If you are exporting basically everything, then you would be better off with SIMPLE_OPTIMIZATIONS. I would still highly encourage you to maintain compatibility of your library with ADVANCED_OPTIMIZATIONS so that users can compile the library source with their project.
First, I need closurebuilder.py to send the full list of files to the closure compiler. ...
In fact, the only solution I can see is having a FooLibrary.ExposeAPI JS file that #require's everything. Surely that can't be right?
You would need to specify an --root of your source folder and specify the namespaces of the leaf nodes of your file dependency tree. You may have better luck with the now deprecated CalcDeps.py script. I still use it for some projects.
What I can't do, apparently, is say "export FooLibrary.*". Wouldn't that make sense?
You can't do that because it only makes sense based on the final usage. You as the library writer wish to export everything, but perhaps a consumer of your library wishes to include the source (uncompiled) version and have more dead code elimination. Library authors are stuck in a kind of middle ground between SIMPLE and ADVANCED optimization levels.
What I have done for this case is maintain a separate exports file for my namespace that exports everything. When compiling a standalone version of my library for distribution, the exports file is included in the compilation. However I can still include the library source (without the exports) into a project and get full dead code elimination. The work/payoff balance of this though must be weighed against just using SIMPLE_OPTIMIZATIONS for the standalone library.
My GeolocationMarker library has an example of this strategy.

cmake best practice

When working with cmake, is it better to work with one large CMakeLists.txt in the root of the project, or as seems to be seen in some places, having one in each subdirectory too?
I would assume something along the lines of for large projects, having one in each directory is better.
If so, where should the threshold be?
I would certainly go for using multiple CMakeListst.txt files.
As a rule of thumb I think you should go for one CMakeLists.txt (and thus subdirectory) per target. So, each library or executable has its own CMakeLists.txt.
You can then create one "master" CMakeLists.txt that includes all the others using the add_subdirectory call. If you take care that you order these statements correctly, you can easily reference previously defined targets in the other CMakeLists.txt file.

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