What exacly is "buidling" from source and how does it work - opencv

So I really cant understand how this work but late me explain. First, just in case you need it, I am running Ubuntu 12.04 64-bit on a laptop.
As a building tool am using CMake. I want to load in to my project OpenCV, MRPT (http://www.mrpt.org/) and libfreenect. All of them have a "source code". What I don't understand is when they say "build from source". How to I make a project with all of them?
Do I need to build each one individually and with some way but then in my project OR do I down load the source code and build them all together at ones? As you can see I'm really confused what I have to do... do I run the CMakeList.txt from each source code and the run one CMakeList.txt that has all the other CMakeList.txt?
In fewer world, if I want to build from source, two or more libraries, how do I do that?
I would like a general answer (how this "build from source" works) and an answer specifically on the the ones I mentioned (CMake, OpenCV, MRPT, libfreenect). I hope I made clear what I don't really understand.

It depends of the 'master' project. In general in the c/c++ universe your project must know how to invoke the build process of each subproject/library OR your project needs to know how to include&link the results after building each external project yourself.
You can also mix the two approaches if needed but I think it cleaner to try to use one if possible.
In the first case if all the subprojects offer cmake building files (CMakeLists.txt) you may try to add_subdirectory() each and see if there are any conflicts. For example google test can be easily included this way and it gives your project some global variables that easy linking later.
Alternatively or if the above approach gives problems or the sub project doesn't provide CMakeLists.txt you can use ExternalProject_add(). It takes more work and you have to handle includes/linking configurations with your project manually but it makes the subproject more independent. For example if there are conflicting targets with your project or the subproject doesn't provide CMakeLists.txt.
The last approach involves building and installing the sub projects separately, using configuration variables in your project to point the includes/libraries paths of the sub project. Check CMake:How To Find Libraries for details.

Related

Using large non-bazel dependencies in a bazel project

I would like to use a very large non-bazel system in a bazel project. Specifically, ROS2. This dependency provides a large number of python, C, and C++ libraries which are built using its own hand-rolled buildsystem. Obviously, I would like to avoid having to translate the entire buildsystem over to bazel.
Broadly, what's the best way of me doing this? In instinct was to use a custom repository rule to download the source (since it's split across many repositories), then use a genrule to call the ROS2 build system. Then write my simple cc_import and py_library rules for each of the individual components that I need.
However, I'm having trouble with the bit where I need to call the foreign build system. It seems that genrules require a list of output files to be specified, while I would like it to make an entire build directory available.
Before I spent any more time on this, I thought I'd ask whether I'm on the right lines since I'm new to bazel. Is this a good strategy? How would you approach this problem? Are there any other projects that mainly use bazel, but call other build systems in this way that I can look at?
As of recent, you can use rules_foreign_cc to call native CMake or make/configure like projects.

Handling complex and large dependencies

Problem
I've been developing a game in C++ in my spare time and I've opted to use Bazel as my build tool since I have never had a ton of luck (or fun) working with make or cmake. I also have dependencies in other languages (python for some of the high level scripting). I'm using glfw for basic window handling and high level graphics support and that works well enough but now comes the problem. I'm uncertain on how I should handle dependencies like glfw in a Bazel world.
For some of my dependencies (like gtest and fruit) I can just reference them in my WORKSPACE file and Bazel handles them automagically but glfw hasn't adopted Bazel. So all of this leads me to ask, what should I do about dependencies that don't use Bazel inside a Bazel project?
Current approach
For many of the simpler dependencies I have, I simply created a new_git_repository entry in my WORKSPACE file and created a BUILD file for the library. This works great until you get to really complicated libraries like glfw that have a number of dependencies on their own.
When building glfw for a Linux machine running X11 you now have a dependency on X11 which would mean adding X11 to my Bazel setup. X11 Comes with its own set of dependencies (the X11 libraries like X11Cursor) and so on.
glfw also tries to provide basic joystick support which is provided by default in Linux which is great! Except that this is provided by the kernel which means that the kernel is also a dependency of my project. Now I shouldn't need anything more than the kernel headers this still seems like a lot to bring in.
Alternative Options
The reason I took the approach I've taken so far is to make the dependencies required to spin up a machine that can successfully build my game very minimal. In theory they just need a C/C++ compiler, Java 8, and Bazel and they're off to the races. This is great since it also means I can create a Docker container that has Bazel installed and do CI/CD really easily.
I could sacrifice this ease and just say that you need to have libraries like glfw installed before attempting to compile the game but that brings the whole which version is installed and how is it all configured problem back up that Bazel is supposed to help solve.
Surely there is a simpler solution and I'm overthinking this?
If the glfw project has no BUILD files, then you have the following options:
Build glfw inside a genrule.
If glfw supports some other build system like make, you could create a genrule that runs the tool. This approach has obvious drawbacks, like the not-to-be-underestimated impracticality of having to declare all inputs of that genrule, but it'd be the simplest way of Bazel'izing glfw.
Pre-build glfw.o and check it into your source tree.
You can create a cc_library rule for it, and put the .o file in the srcs. Even though this solution is the least flexible of all because you not only restrict the target platform to whatever the .o was built for, but also make it harder to reproduce the whole build, the benefits are sometimes worth the costs.
I view this approach as a last resort. Even in Bazel's own source code there's one cc_library.srcs that includes a raw object file, because it was worth it, as the commit message of 92caf38 explains.
Require that glfw be installed.
You already considered this option. Some people may prefer this to the other approaches.

FunScript: How to access TypeScript.Api<...>

I'm getting started with FunScript with a working example. Using Nuget to add the needed libraries, it works well.
In watching a 2013 video on channel9, they are making use of TypeScript.Api<...> to load types from typescript definition files.
I'm however unable to find this type provider anywhere.
Where is it located?
I realized that a good number of the type definitions have been compiled into libraries and available on nuget but I can't really use this since some of the code will be local typescript definition files.
The questions therefore are
Where is the TypeScript.Api<...> type provider?
If it is not available or the best way to use typescript definition, what other options exists.
As Thomas said, the type provider was removed mainly because it couldn't generate generic types, but the idea is to bring it back at some point.
For the moment, though not ideal, you can generate your own bindings following these steps.
Download or clone Funscript repository
git clone https://github.com/ZachBray/FunScript
Build the project
cd FunScript
build.cmd
This needs to be improved but for now you need to zip the .d.ts files you want to convert and then:
cd build\TypeScript
bin\FunScript.TypeScript.exe C:\Path\to\typedefinitions.zip
cd Output
Please note the first time you build the definitions it may take several minutes. Once it's done in the output folder you'll find the compiled .dll libraries with the bindings.
Also, while you're at it. It's better if you use the FunScript version you just build into build\main\bin, as it will probably be more updated than the nuget package.
Good luck and have fun(script)!
There were a bunch of changes in FunScript, so the TypeScript.Api<...> type provider is no longer the recommended way of calling JavaScript libraries from FunScript.
Instead, the bindings for JavaScript libraries are pre-generated and you can find them as packages on NuGet, if you search for the FunScript tag (NuGet search is not very good, so you may need to go through a number of pages to find the one you need...).
If you want to use a local TypeScript definition, then you'll need to run the command line tool to generate the bindings. The F# Atom plugin does this in the build script, so looking there is a good place to start. It has a local copy of various TypeScript bindings in the typings folder (together with the FunScript binaries needed to process them).
I liked the type provider approach much better, but sadly, type providers are somewhat restricted in what kind of types they can provide, so it wasn't all that powerful...

TFS Build custom activity requiring more assemblies than needed

I've just written the first version of a workflow activity that will run Resharper's Code Issues on the projects and parse the output to display the issues as build warnings and errors.
At first, I was going to just call Resharper's command line and parse the resulting xml manually. After fiddling with the dlls in Resharper's SDK (through disassembly mostly), I found a way to parse the results using it's own public classes, which I figured was a much more elegant and safe way to do this.
The first problem I have is that that nuget package is absolutely huge. There is 140mb of files in there, which to me is absurd for a single, unpartitioned package. There seems to be such heavy coupling between them that by using just a few model classes and the parser class, I have to drag a dozen or so of those dlls along, some of them which seemingly have nothing to do with the main dlls I need. This is not a show stopper though, I'm struggling with something else now:
In the end, I managed to track down the dependencies I needed to 41 assemblies (which is, again, insane, but alas). Initially, I tried removing everything and adding the missing references one by one, but this turned out to be unreliable, still missing some indirect references, even after compiling successfully. Then, I decided to code a small console application to find all referenced assemblies in the main Resharper assemblies I used, which gave me the 41 references I mentioned. This is the code I used to find every dependency.
Since these are custom activities we are talking about, I decided to create a unit test project to validate them. Using these 41 references only, everything works correctly.
When I added the activity to the build workflow though, and pointed the build controller to the source control folder containing the required assemblies, every time I schedule a build, the process fails stating that I need one extra dll from Resharper's SDK. For example, this is the first one it asks:
Could not load file or assembly 'AsyncBridge.Net35, PublicKeyToken=b3b1c0202c0d6a87' or one of its dependencies. The system cannot find the file specified. (type FileNotFoundException)
When I add this specific assembly to the TFS folder, I get another similar error for another dll, and this keeps going on and on.
What I wanted to know is how can I know exactly which assemblies a workflow XAML will need in order to run correctly? My custom activity dll has two specific CodeActivities and a XAML only activity that uses these two. This XAML acticity is what I'm directly using in the modified workflow template.
I see that besides the references in my project, the XAML activity also contains a TextExpression.ReferencesForImplementation section, with some assembly names. I've run my dependency finder program on those dependencies too, and the results are the same 41 assemblies already at the TFS folder.
Meanwhile I'll go with having the whole SDK into the custom assemblies folder, but I would really like to avoid this in the future since it has such an enormous amount of unneeded and big dlls in there.
First, we have request for our command line tool to support workflow activity and we decided to implement just plain MsBuild task which is universal and works in TFS too. Task and targets files are included in ReSharper CLT 8.2.
Second, if you still want to implement workflow activity it's pretty easy to do with new API in CLT, designed specially for custom processing of found issues - http://confluence.jetbrains.com/display/NETCOM/Custom+InspectCode+Issue+Logger.
And last, but not least, you do not need to put in VCS binaries of ReSharper SDK package.
Use NuGet's restore package functionality.
If you have any other questions I'll be glad to answer them.
A custom activity is being load and run by .NET CLR like any other .NET program. If the stack trace reports a missing file, then it's required by the CLR and you can't change this fact without refactoring your code.
Having an entire SDK references in the custom assembly folder doesn't make sense. I would prefer GAC deployment over huge binaries folder in the source control. Or maybe consider having these activities running an pre\post build scripts in MSBuild or PowerShell.

Managing/Using libraries with Debug builds vs Release builds

I'm curious about everyones practices when it comes to using or distributing libraries for an application that you write.
First of all, when developing your application do you link the debug or release version of the libraries? (For when you run your application in debug mode)
Then when you run your app in release mode just before deploying, which build of the libraries do you use?
How do you perform the switch between your debug and release version of the libraries? Do you do it manually, do you use macros, or whatever else is it that you do?
I would first determine what requirements are needed from the library:
Debug/Release
Unicode support
And so on..
With that determined you can then create configurations for each combination required by yourself or other library users.
When compiling and linking it is very important that you keep that libraries and executable consistent with respect to configurations used i.e. don't mix release & debug when linking.
I know on the Windows/VS platform this can cause subtle memory issues if debug & release libs are mixed within an executable.
As Brian has mentioned to Visual Studio it's best to use the Configuration Manager to setup how you want each configuration you require to be built.
For example our projects require the following configurations to be available depending on the executable being built.
Debug+Unicode
Debug+ASCII
Release+Unicode
Release+ASCII
The users of this particular project use the Configuration Manager to match their executable requirements with the project's available configurations.
Regarding the use of macros, they are used extensively in implementing compile time decisions for requirements like if the debug or release version of a function is to be linked. If you're using VS you can view the pre-processor definitions attribute to see how the various macros are defined e.g. _DEBUG _RELEASE, this is how the configuration controls whats compiled.
What platform are you using to compile/link your projects?
EDIT: Expanding on your updated comment..
If the Configuration Manager option is not available to you then I recommend using the following properties from the project:
Linker->Additional Library Directories or Linker->Input
Use the macro $(ConfigurationName) to link with the appropriate library configuration e.g. Debug/Release.
$(ProjectDir)\..\third-party-prj\$(ConfigurationName)\third-party.lib
Build Events or Custom Build Step configuration property
Execute a copy of the required library file(s) from the dependent project prior (or after) to the build occurring.
xcopy $(ProjectDir)\..\third-party-prj\$(ConfigurationName)\third-party.dll $(IntDir)
The macro $(ProjectDir) will be substituted for the current project's location and causes the operation to occur relative to the current project.
The macro $(ConfigurationName) will be substituted for the currently selected configuration (default is Debug or Release) which allows the correct items to be copied depending on what configuration is being built currently.
If you use a regular naming convention for your project configurations it will help, as you can use the $(ConfigurationName) macro, otherwise you can simply use a fixed string.
I use VS. The way that I do it is that the libraries I need through the references of the project. Which basically just says in what folder to look for a specific library at project load time. I develop my libraries to be as project independent or reusable as possible. Therefore they are all projects of their own. So of the libraries that I need for a specific project, I create a "3rdParty" or "libs" folder at the same level as my "src" folder in my svn folder tree. I tend to only use released libraries, but when I get some unknown issues and want to switch to debug, I manually copy a debug version of the files in the "lib" folder and reload the project.
I am unsure wether I should be keeping both debug and released versions in my svn tree. Although since they are projects of their own, keeping them in the svn tree of another project doesn't right. They can be built again without an hitch at any moment.
And then I wanted to find a way of making the switch more...hmmm...well basically automatic if you while, but that's not what I really mean. It just feels that switching the files manually between released and debug isn't right. Maybe I haven't found it yet, but what I would like is an option that would do like:
For library "stack.dll" look in "......\3rdParty\" for release and "......\3rdPartyD\" for debug.
Anything that those something like I don't know. What do you suggest?
Remember libraries are external projects. There the built files are totally elsewhere. In fact think of it as you have to check out another project, build it, and copy the built library if you want another copy. How would you set that up?

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