Strawman proposals for CMake support
Hi, I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages: (1) Users have a hard time integrating Boost into their build system, which is CMake more often than not. (2) Prospective Boost developers are sometimes driven away from submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base. FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like: 1. We start requiring that new libraries support both Boost.Build and CMake. 2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based. 3. We release Boost with dual support for a while, letting time for things to bake. 4. We remove the requirement that Boot libraries can be built with B2. Libraries (existing and new ones) are free to provide such support, but they are not required to. This would bring CMake to the status of "primary" build system for Boost. This could be based on Paul Fultz's work in progress at [1]. This has the following advantages (in the long term): - Less technical debt because we only have one "official" build system to maintain. - The build system is uniform across all of Boost, which means it's easier for folks to maintain it and understand it. - It gives maximal flexibility to CMake-based users. However, it has the following drawbacks: - We'll need to do a wholesale migration to build system XYZ when CMake is not cool anymore. - It's harder to get buy-in from some developers that love Boost.Build SECOND PROPOSAL =============== The second proposal is to make Boost into an almost build-system agnostic collection of libraries. Basically, 1. Provide CMake package config files for all Boost libraries so that they can be used from CMake (either automatically, manually, or a mixture of both). This could be based on Peter Dimov's work at [2] (or [3], not sure which one is most current). 2. Make it possible to build CMake-based projects from Boost.Build, or the other way around, or provide a build system agnostic script to build all of Boost. This way, Boost libraries can decide whether they want to support B2 or CMake. This has the following advantages: - Possibly easier to implement - We could possibly support other build systems too (e.g. if a Boost author really wants to use scons for his/her library) - We don't have to do a wholesale move to XYZ when CMake is not cool anymore I see the following disadvantages: - Boost's infrastructure could grow more complex as a result - Our build system would be less uniform - We would have to depend on all the build systems that we want Boost libraries to be usable with My personal preference is towards the first option, since I think it would be simpler in the long term. I could certainly be convinced otherwise. There are probably other ways we can solve problems (1) and (2) exposed above. There are also certainly advantages and disadvantages that I forgot to mention above. I'd love to get some feedback on those two approaches and see whether one of them (or something else completely) can get some consensus on this list. Cheers, Louis [1]: https://github.com/boost-cmake/bcm [2]: https://github.com/pdimov/boost-cmake-demo-2 [3]: https://github.com/pdimov/boost-cmake-demo -- View this message in context: http://boost.2283326.n4.nabble.com/Strawman-proposals-for-CMake-support-tp46... Sent from the Boost - Dev mailing list archive at Nabble.com.
Hi Louis, while (as should be obvious) I'm strongly favouring the second proposal (if I had to pick between the two), there are nonetheless points I'd like to add to the rest of the message. I hope that doesn't dilute the rest of it. On 18.07.2017 21:09, Louis Dionne via Boost wrote:
Hi,
I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages:
I keep reading various "analyses" about where the supposed pain points are with the current Boost infrastructure, and following that, what requirements should be met by any future version. But all too often, the discussion then jumps to solutions, without ever consolidating on the problem analysis. At least it's my impression that there are multiple "camps" of users all arguing from very different perspectives, representing different "development cultures".
(1) Users have a hard time integrating Boost into their build system, which is CMake more often than not.
Here is one of the fault lines: what is meant by "integrating Boost" ? Some have argued that it ought to be possible to actually build Boost as part of another project (thus integrating means the build system. For others, it merely means the ability to build their own project with Boost as an external (precompiled) dependency. How frequent are these two requests, and how important is it for Boost to meet them ?(2) Prospective Boost developers are sometimes driven away from
submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base.
I agree.
FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like:
1. We start requiring that new libraries support both Boost.Build and CMake.
(Why ? If you decide to move to CMake, why requiring new libraries to support anything other than CMake ?)
2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based.
3. We release Boost with dual support for a while, letting time for things to bake.
4. We remove the requirement that Boot libraries can be built with B2. Libraries (existing and new ones) are free to provide such support, but they are not required to.
This would bring CMake to the status of "primary" build system for Boost. This could be based on Paul Fultz's work in progress at [1]. This has the following advantages (in the long term): - Less technical debt because we only have one "official" build system to maintain. - The build system is uniform across all of Boost, which means it's easier for folks to maintain it and understand it. - It gives maximal flexibility to CMake-based users.
However, it has the following drawbacks: - We'll need to do a wholesale migration to build system XYZ when CMake is not cool anymore. - It's harder to get buy-in from some developers that love Boost.Build
SECOND PROPOSAL =============== The second proposal is to make Boost into an almost build-system agnostic collection of libraries. Basically,
1. Provide CMake package config files for all Boost libraries so that they can be used from CMake (either automatically, manually, or a mixture of both). This could be based on Peter Dimov's work at [2] (or [3], not sure which one is most current).
2. Make it possible to build CMake-based projects from Boost.Build, or the other way around, or provide a build system agnostic script to build all of Boost. This way, Boost libraries can decide whether they want to support B2 or CMake.
This has the following advantages: - Possibly easier to implement - We could possibly support other build systems too (e.g. if a Boost author really wants to use scons for his/her library) - We don't have to do a wholesale move to XYZ when CMake is not cool anymore
All true.
I see the following disadvantages: - Boost's infrastructure could grow more complex as a result - Our build system would be less uniform
In fact, if we go to the extreme, there wouldn't be a single "boost build system" any longer. There would be a standard (a set of conventions) for * naming generated files * directory structure * required documentation * entry points to trigger a build / test run * etc. all to encapsulate the actual build process of individual libraries, while still providing the same consistency to Boost users. (Note that this does not in itself open the door for arbitrary build tools to be used. That would be a separate, orthogonal discussion.)
- We would have to depend on all the build systems that we want Boost libraries to be usable with
Now this is quite fuzzy again. Your implied requirement seems to be that every user may want to build boost, as a whole, and thus will need all the tools. I think this is nuts. The first problem is again that you think of Boost as a single entity. While that has some appeal to some (for example for legal reasons), I think technically we should really start thinking about Boost libraries as independent components, so a "Boost user" really becomes a "Boost.Compute" user or a "Boost.FileSystem" user, etc., which massively reduces the problem. Second, most "users" don't need to build the Boost library they are using, or at least, they don't need to build it as an integral part of whatever other project they are working on. So they could treat it the same way as any other third-party dependency. Thirdly, yes, if we allow different build tools to be used, it means that those who want to build these libs will need to adapt. I simply trust that the individual (Boost) library communities can figure out much better what tools suite them best than what any top-down steering committee could. Stefan -- ...ich hab' noch einen Koffer in Berlin...
Le 19.07.17 à 03:09, Louis Dionne via Boost a écrit :
Hi,
I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages:
(1) Users have a hard time integrating Boost into their build system, which is CMake more often than not.
(2) Prospective Boost developers are sometimes driven away from submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base.
FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like:
1. We start requiring that new libraries support both Boost.Build and CMake.
2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based.
3. We release Boost with dual support for a while, letting time for things to bake.
4. We remove the requirement that Boot libraries can be built with B2. Libraries (existing and new ones) are free to provide such support, but they are not required to.
This would bring CMake to the status of "primary" build system for Boost. This could be based on Paul Fultz's work in progress at [1]. This has the following advantages (in the long term): - Less technical debt because we only have one "official" build system to maintain. - The build system is uniform across all of Boost, which means it's easier for folks to maintain it and understand it. - It gives maximal flexibility to CMake-based users.
However, it has the following drawbacks: - We'll need to do a wholesale migration to build system XYZ when CMake is not cool anymore. - It's harder to get buy-in from some developers that love Boost.Build
I personally believe that "anything" between the tool (cmake or boost.build) and the developers should be avoided, whether it is a "good idea" or not. So I will not be in favour of libraries such as, no offense (**), BCM. I would welcome a tool that dissects the Jamfiles and generates even a rough/approximate CMakeLists.txt to start with. But I would "really" rather focus on the interface between the superproject and the libraries, and among the libraries themselves to cover the inner dependencies (flow of information basically: expected targets, naming conventions, build variants, etc). Concerning the infrastructure, it would be good to list what should be addressed there (servers, doc generation, runners, CI, dashboard, etc). I believe most of the people do not know what it involves, and we sadly lost Rene in this. To summarize: I would like to focus on the "CMakeLists.txt" interface rather than the implementation, because this is the big unknown to me right now, and the infrastructure should receive enough attention otherwise it will kill the intent. I can volunteer for the infrastructure. (**) (just in case my wording for "excluding" a proposal is not inclusive enough.)
SECOND PROPOSAL =============== The second proposal is to make Boost into an almost build-system agnostic collection of libraries. Basically,
1. Provide CMake package config files for all Boost libraries so that they can be used from CMake (either automatically, manually, or a mixture of both). This could be based on Peter Dimov's work at [2] (or [3], not sure which one is most current).
2. Make it possible to build CMake-based projects from Boost.Build, or the other way around, or provide a build system agnostic script to build all of Boost. This way, Boost libraries can decide whether they want to support B2 or CMake.
This sounds to me like designing a "build generator" (*) ... for a "build generator" (boost.build or cmake). Or a meta-builder for a meta-builder ... The idea itself might be appealing but sounds bad in the end. If the intent is to ease the development and shipping of boost libraries, then adding a layer between the developer and cmake core functionalities is not helping, and the tool will be just a subset of what cmake can do. To summarize: I do not like this proposal. (*) choose the name of your liking Thanks, Raffi
This has the following advantages: - Possibly easier to implement - We could possibly support other build systems too (e.g. if a Boost author really wants to use scons for his/her library) - We don't have to do a wholesale move to XYZ when CMake is not cool anymore
I see the following disadvantages: - Boost's infrastructure could grow more complex as a result - Our build system would be less uniform - We would have to depend on all the build systems that we want Boost libraries to be usable with
My personal preference is towards the first option, since I think it would be simpler in the long term. I could certainly be convinced otherwise.
There are probably other ways we can solve problems (1) and (2) exposed above. There are also certainly advantages and disadvantages that I forgot to mention above. I'd love to get some feedback on those two approaches and see whether one of them (or something else completely) can get some consensus on this list.
Cheers, Louis
[1]: https://github.com/boost-cmake/bcm [2]: https://github.com/pdimov/boost-cmake-demo-2 [3]: https://github.com/pdimov/boost-cmake-demo
-- View this message in context: http://boost.2283326.n4.nabble.com/Strawman-proposals-for-CMake-support-tp46... Sent from the Boost - Dev mailing list archive at Nabble.com.
_______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
On Wed, 2017-07-19 at 14:37 +0200, Raffi Enficiaud via Boost wrote:
Le 19.07.17 à 03:09, Louis Dionne via Boost a écrit :
Hi,
I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages:
(1) Users have a hard time integrating Boost into their build system, which is CMake more often than not.
(2) Prospective Boost developers are sometimes driven away from submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base.
FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like:
1. We start requiring that new libraries support both Boost.Build and CMake.
2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based.
3. We release Boost with dual support for a while, letting time for things to bake.
4. We remove the requirement that Boot libraries can be built with B2. Libraries (existing and new ones) are free to provide such support, but they are not required to.
This would bring CMake to the status of "primary" build system for Boost. This could be based on Paul Fultz's work in progress at [1]. This has the following advantages (in the long term): - Less technical debt because we only have one "official" build system to maintain. - The build system is uniform across all of Boost, which means it's easier for folks to maintain it and understand it. - It gives maximal flexibility to CMake-based users.
However, it has the following drawbacks: - We'll need to do a wholesale migration to build system XYZ when CMake is not cool anymore. - It's harder to get buy-in from some developers that love Boost.Build
I personally believe that "anything" between the tool (cmake or boost.build) and the developers should be avoided, whether it is a "good idea" or not. So I will not be in favour of libraries such as, no offense (**), BCM.
The point of BCM is not to abstract away the tool(although some developers would like it to do that). Only to provide some functions for the boilerplate in involved in generation of package configuration, to help provide consistency with the testing, and provide support for documentation(ss cmake does not provide modules for boost documentation).
I would welcome a tool that dissects the Jamfiles and generates even a rough/approximate CMakeLists.txt to start with.
But I would "really" rather focus on the interface between the superproject and the libraries, and among the libraries themselves to cover the inner dependencies (flow of information basically: expected targets, naming conventions, build variants, etc).
I think any cmake should follow closely this: https://github.com/boost-cmake/boost
Concerning the infrastructure, it would be good to list what should be addressed there (servers, doc generation, runners, CI, dashboard, etc). I believe most of the people do not know what it involves, and we sadly lost Rene in this.
To summarize: I would like to focus on the "CMakeLists.txt" interface rather than the implementation, because this is the big unknown to me right now, and the infrastructure should receive enough attention otherwise it will kill the intent.
I can volunteer for the infrastructure.
(**) (just in case my wording for "excluding" a proposal is not inclusive enough.)
SECOND PROPOSAL =============== The second proposal is to make Boost into an almost build-system agnostic collection of libraries. Basically,
1. Provide CMake package config files for all Boost libraries so that they can be used from CMake (either automatically, manually, or a mixture of both). This could be based on Peter Dimov's work at [2] (or [3], not sure which one is most current).
2. Make it possible to build CMake-based projects from Boost.Build, or the other way around, or provide a build system agnostic script to build all of Boost. This way, Boost libraries can decide whether they want to support B2 or CMake.
This sounds to me like designing a "build generator" (*) ... for a "build generator" (boost.build or cmake). Or a meta-builder for a meta-builder ... The idea itself might be appealing but sounds bad in the end. If the intent is to ease the development and shipping of boost libraries, then adding a layer between the developer and cmake core functionalities is not helping, and the tool will be just a subset of what cmake can do.
To summarize: I do not like this proposal.
(*) choose the name of your liking
Thanks, Raffi
This has the following advantages: - Possibly easier to implement - We could possibly support other build systems too (e.g. if a Boost author really wants to use scons for his/her library) - We don't have to do a wholesale move to XYZ when CMake is not cool anymore
I see the following disadvantages: - Boost's infrastructure could grow more complex as a result - Our build system would be less uniform - We would have to depend on all the build systems that we want Boost libraries to be usable with
My personal preference is towards the first option, since I think it would be simpler in the long term. I could certainly be convinced otherwise.
There are probably other ways we can solve problems (1) and (2) exposed above. There are also certainly advantages and disadvantages that I forgot to mention above. I'd love to get some feedback on those two approaches and see whether one of them (or something else completely) can get some consensus on this list.
Cheers, Louis
[1]: https://github.com/boost-cmake/bcm [2]: https://github.com/pdimov/boost-cmake-demo-2 [3]: https://github.com/pdimov/boost-cmake-demo
-- View this message in context: http://boost.2283326.n4.nabble.com/Strawman- proposals-for-CMake-support-tp4696989.html Sent from the Boost - Dev mailing list archive at Nabble.com.
_______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/b oost
_______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boo st
Le 19.07.17 à 16:39, paul via Boost a écrit :
On Wed, 2017-07-19 at 14:37 +0200, Raffi Enficiaud via Boost wrote:
Le 19.07.17 à 03:09, Louis Dionne via Boost a écrit :
Hi,
I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages:
(1) Users have a hard time integrating Boost into their build system, which is CMake more often than not.
(2) Prospective Boost developers are sometimes driven away from submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base.
FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like:
1. We start requiring that new libraries support both Boost.Build and CMake.
2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based.
3. We release Boost with dual support for a while, letting time for things to bake.
4. We remove the requirement that Boot libraries can be built with B2. Libraries (existing and new ones) are free to provide such support, but they are not required to.
This would bring CMake to the status of "primary" build system for Boost. This could be based on Paul Fultz's work in progress at [1]. This has the following advantages (in the long term): - Less technical debt because we only have one "official" build system to maintain. - The build system is uniform across all of Boost, which means it's easier for folks to maintain it and understand it. - It gives maximal flexibility to CMake-based users.
However, it has the following drawbacks: - We'll need to do a wholesale migration to build system XYZ when CMake is not cool anymore. - It's harder to get buy-in from some developers that love Boost.Build
I personally believe that "anything" between the tool (cmake or boost.build) and the developers should be avoided, whether it is a "good idea" or not. So I will not be in favour of libraries such as, no offense (**), BCM.
The point of BCM is not to abstract away the tool(although some developers would like it to do that). Only to provide some functions for the boilerplate in involved in generation of package configuration, to help provide consistency with the testing, and provide support for documentation(ss cmake does not provide modules for boost documentation).
What I also really dislike in this approach is to have a very hard dependencies to whatever library that is lying in the superproject. My goal is to be able to distribute boost.test (library and tests parts) independently of boost as well. Again that is to me the core of the problem: what CMake variables (or interface) is needed in individual libraries and in the superproject to have a decent global infrastructure?
I would welcome a tool that dissects the Jamfiles and generates even a rough/approximate CMakeLists.txt to start with.
But I would "really" rather focus on the interface between the superproject and the libraries, and among the libraries themselves to cover the inner dependencies (flow of information basically: expected targets, naming conventions, build variants, etc).
I think any cmake should follow closely this:
I will be honest: for the boost.test part, I will just rewrite everything in there. This is just an empty shell that is providing the very easy part, the tip of the iceberg. And this is exactly my point that is not addressed in your reply: what is supposed to be in the CMakeLists.txt in terms of inter dependencies? For generating the doc? for testing and sharing their results? for being able to unit test the CMakeLists.txt itself? I believe, and this is certainly better done in another thread, that the provided example does not address any of the main concerns, it just declares a target, and adds a couple of dependencies to its interface. That is not enough. Raffi
On Wed, 2017-07-19 at 17:06 +0200, Raffi Enficiaud via Boost wrote:
Le 19.07.17 à 16:39, paul via Boost a écrit :
On Wed, 2017-07-19 at 14:37 +0200, Raffi Enficiaud via Boost wrote:
Le 19.07.17 à 03:09, Louis Dionne via Boost a écrit :
Hi,
I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages:
(1) Users have a hard time integrating Boost into their build system, which is CMake more often than not.
(2) Prospective Boost developers are sometimes driven away from submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base.
FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like:
1. We start requiring that new libraries support both Boost.Build and CMake.
2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based.
3. We release Boost with dual support for a while, letting time for things to bake.
4. We remove the requirement that Boot libraries can be built with B2. Libraries (existing and new ones) are free to provide such support, but they are not required to.
This would bring CMake to the status of "primary" build system for Boost. This could be based on Paul Fultz's work in progress at [1]. This has the following advantages (in the long term): - Less technical debt because we only have one "official" build system to maintain. - The build system is uniform across all of Boost, which means it's easier for folks to maintain it and understand it. - It gives maximal flexibility to CMake-based users.
However, it has the following drawbacks: - We'll need to do a wholesale migration to build system XYZ when CMake is not cool anymore. - It's harder to get buy-in from some developers that love Boost.Build
I personally believe that "anything" between the tool (cmake or boost.build) and the developers should be avoided, whether it is a "good idea" or not. So I will not be in favour of libraries such as, no offense (**), BCM.
The point of BCM is not to abstract away the tool(although some developers would like it to do that). Only to provide some functions for the boilerplate in involved in generation of package configuration, to help provide consistency with the testing, and provide support for documentation(ss cmake does not provide modules for boost documentation).
What I also really dislike in this approach is to have a very hard dependencies to whatever library that is lying in the superproject. My goal is to be able to distribute boost.test (library and tests parts) independently of boost as well.
Yes, it doesnt prevent that. In the standalone builds, BCM is just another dependency the user would install(either manually or through a package manager). This is why a file would start with `find_package(BCM)` so it will search for the installed BCM, in the same way it would search for Boost.Config when you call `find_package(boost_config)`. Unless by independent, you mean zero dependencies. In this scenario, you can call to `find_package(BCM)`, if not found do something else besides calling the bcm module functions. Of course, creating zero dependency libraries should not be the focus of the cmake. These are boost libraries that will be integrated into boost infrastructure. I think it should up to the each individual author to support zero-dependency library, while overall all boost libraries should support standalone installation.
Again that is to me the core of the problem: what CMake variables (or interface) is needed in individual libraries and in the superproject to have a decent global infrastructure?
There is no variables that need to be defined, but we want to create a target for the library, an alias target with the namespace, install the target and header files, and generate the package configuration.
I would welcome a tool that dissects the Jamfiles and generates even a rough/approximate CMakeLists.txt to start with.
But I would "really" rather focus on the interface between the superproject and the libraries, and among the libraries themselves to cover the inner dependencies (flow of information basically: expected targets, naming conventions, build variants, etc).
I think any cmake should follow closely this:
I will be honest: for the boost.test part, I will just rewrite everything in there. This is just an empty shell that is providing the very easy part, the tip of the iceberg.
And this is exactly my point that is not addressed in your reply: what is supposed to be in the CMakeLists.txt in terms of inter dependencies?
What do mean "interdependencies"?
For generating the doc?
We will definitely need a cmake module for this as cmake doesn't support boost doc directly.
for testing and sharing their results?
That should all happen within CTest.
for being able to unit test the CMakeLists.txt itself?
Building, testing and installing should be enough to test the cmake scripts.
I believe, and this is certainly better done in another thread, that the provided example does not address any of the main concerns, it just declares a target, and adds a couple of dependencies to its interface.
That is not enough.
Raffi
_______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boo st
On Tue, 2017-07-18 at 18:09 -0700, Louis Dionne via Boost wrote:
Hi,
I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages:
(1) Users have a hard time integrating Boost into their build system, which is CMake more often than not.
(2) Prospective Boost developers are sometimes driven away from submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base.
FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like:
1. We start requiring that new libraries support both Boost.Build and CMake.
2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based.
We need to start by defining the use cases we want to support. That is we want to support: * Prebuilt libraries with `find_package` * Integrated builds with `add_subdirectory` * Bulding libraries standalone(ignoring cycles for now) * Running tests with all of boost * Running tests standalone * Generating documenation... Of course, as we start to move to cmake, we can start by getting the first three cases done, and then move to integrating the tests. Then next phase would be integrating the documentation. I think it important that we start outlining these goals. Especially since users between prebuilt vs integrated builds don't agree, and we dont want to support one while ignoring the other case. I think its important and feasible to support both camps.
Proposals worthy of discussion. Might been a good idea to offer them before the decision was announced. Robert Ramey
Proposals worthy of discussion. Might been a good idea to offer them before the decision was announced.
Robert Ramey
You seem to be implying that I alone announced or took that decision, which is a lot to bear. I'm trying to be constructive because I love this community, I owe a lot to it, and I want it to flourish. Those are things we both have in common, so let's build on them. Louis -- View this message in context: http://boost.2283326.n4.nabble.com/Strawman-proposals-for-CMake-support-tp46... Sent from the Boost - Dev mailing list archive at Nabble.com.
Gesendet: Mittwoch, 19. Juli 2017 um 03:09 Uhr Von: "Louis Dionne via Boost" <boost@lists.boost.org> An: boost@lists.boost.org Cc: "Louis Dionne" <ldionne.2@gmail.com> Betreff: [boost] Strawman proposals for CMake support
Hi,
I'd like to expose two strawman proposals for adding CMake support to Boost. Both proposals would solve the following problems, with different advantages and disadvantages:
(1) Users have a hard time integrating Boost into their build system, which is CMake more often than not.
(2) Prospective Boost developers are sometimes driven away from submitting because they would have to learn Boost.Build, which is not widely used and has a limited knowledge base.
FIRST PROPOSAL ============== The first proposal is to move completely to CMake and to render Boost.Build support optional. The possible rollout plan would look something like:
1. We start requiring that new libraries support both Boost.Build and CMake.
2. We start adding CMake support to existing libraries. This will take time. 2.1 We start moving our infrastructure to be CMake-based.
3. We release Boost with dual support for a while, letting time for things to bake.
4. We remove the requirement that Boot libraries can be built with B2. Libraries (existing and new ones) are free to provide such support, but they are not required to.
This would bring CMake to the status of "primary" build system for Boost. This could be based on Paul Fultz's work in progress at [1]. This has the following advantages (in the long term): - Less technical debt because we only have one "official" build system to maintain. - The build system is uniform across all of Boost, which means it's easier for folks to maintain it and understand it. - It gives maximal flexibility to CMake-based users.
However, it has the following drawbacks: - We'll need to do a wholesale migration to build system XYZ when CMake is not cool anymore. - It's harder to get buy-in from some developers that love Boost.Build
SECOND PROPOSAL =============== The second proposal is to make Boost into an almost build-system agnostic collection of libraries. Basically,
1. Provide CMake package config files for all Boost libraries so that they can be used from CMake (either automatically, manually, or a mixture of both). This could be based on Peter Dimov's work at [2] (or [3], not sure which one is most current).
2. Make it possible to build CMake-based projects from Boost.Build, or the other way around, or provide a build system agnostic script to build all of Boost. This way, Boost libraries can decide whether they want to support B2 or CMake.
This has the following advantages: - Possibly easier to implement - We could possibly support other build systems too (e.g. if a Boost author really wants to use scons for his/her library) - We don't have to do a wholesale move to XYZ when CMake is not cool anymore
I see the following disadvantages: - Boost's infrastructure could grow more complex as a result - Our build system would be less uniform - We would have to depend on all the build systems that we want Boost libraries to be usable with
My personal preference is towards the first option, since I think it would be simpler in the long term. I could certainly be convinced otherwise.
There are probably other ways we can solve problems (1) and (2) exposed above. There are also certainly advantages and disadvantages that I forgot to mention above. I'd love to get some feedback on those two approaches and see whether one of them (or something else completely) can get some consensus on this list.
Response to these ideas, but also on the whole plan. boost.build has made boost independent from 3rd party build systems, its historically grown. Its not your workhorse, thats C++, boost.build is a good part of your infrastructure, kind of the roads for your workhorse. Looking at the recent survey from JetBrains, the C++ community at large is using different roads today: https://www.jetbrains.com/research/devecosystem-2017/cpp/ 5% boost build, 34% CMake. CMake added server mode this year, driving adoption from the IDE field (think VS/QtCreator here) to CMake. Its good to see boost adopting to this. One way that hasn't been discussed so far afaik is, that CMake also provides generators for build systems. One could write a CMake generator as an Adaptor to boost.build. This only could be done by boost, would ensure that the generated boost.build files have a certain standard, the current infrastructure would suddenly still be useful, even when new libraries don't come with author supported boost.build files, boost would be able to generate these through the provided CMake files. This knowledge could be useful in the future to adopt other build systems such as Meson too. This solution would serve your current, boost.build based user base, as none would have to convert to CMake, while boost it self would be able to add CMake support to its libraries, offering two build systems instead of one. The current infrastructure would not need to be rewritten and no one would have to reinvent the wheel very often... thanks, Jens Weller
participants (6)
-
Jens Weller -
Louis Dionne -
paul -
Raffi Enficiaud -
Robert Ramey -
Stefan Seefeld