How to build gem whose dependencies depend of the platform?

Ruby
1

Hi!

I need to build a gem whose dependencies are dependent of the platform
itself. For example when gem install my_gem is issued under Windows,
then in gemspec i have to have spec.add_dependency(“gemX”), but if the
command is executed under linux then i need to have
spec.add_dependency(“gemY”).

Is there any easy way to do this or should i just do it like this
instead:

  1. remove all platform specific dependencies from gemspec
  2. when loading the gem, then use RUBY_PLATFORM to decide what gems to
    load and rescue Gem::LoadError to print out friendly messages like
    “please install gemX”

Jarmo

2

On Jan 26, 7:25pm, Jarmo P. [email protected] wrote:

  1. remove all platform specific dependencies from gemspec
  2. when loading the gem, then use RUBY_PLATFORM to decide what gems to
    load and rescue Gem::LoadError to print out friendly messages like
    “please install gemX”

This one is the best approach. Have that clearly in the documentation
and the error you present to the user is the best option.

The other will be generate one gem for every platform and indicate
there the dependencies. Lot of work for you :stuck_out_tongue:

3

Ok, but this is not best solution also since user:

  1. gem install mylib
  2. create a script and require "mylib"
  3. run that script
  4. get an error about missing dependency
  5. nevertheless of just running gem install, user needs to run gem
    install again

It just feels not user friendly way to solve it. Another way would be
to create separate gems of course, but it’s not a good way either.

Jarmo P.

IT does really matter - http://www.itreallymatters.net

4

On 2011-01-29, at 12:21, Jarmo P. wrote:

I need to build a gem whose dependencies are dependent of the platform
itself. For example when gem install my_gem is issued under Windows,
then in gemspec i have to have spec.add_dependency(“gemX”), but if the
command is executed under linux then i need to have
spec.add_dependency(“gemY”).

I have solved this by making the gem depend on the “bundler” gem, and
then put the gem dependecies into a Gemfile, and run the equivalent of
“bundle install” as a post-install script. This takes care of
everything. The only thing I am missing is that the dependencies are
visible when inspecting the gem.

Having RubyGems drop the gemspec dependencies in favor of Gemfile
dependencies would be my preferred way.

–
With kind regards
Uwe K.
Kubosch Consulting
[email protected]

5

On Jan 29, 9:55am, Uwe K. [email protected] wrote:

On 2011-01-29, at 12:21, Jarmo P. wrote:

I need to build a gem whose dependencies are dependent of the platform
itself. For example when gem install my_gem is issued under Windows,
then in gemspec i have to have spec.add_dependency(“gemX”), but if the
command is executed under linux then i need to have
spec.add_dependency(“gemY”).

I have solved this by making the gem depend on the “bundler” gem, and then put
the gem dependecies into a Gemfile, and run the equivalent of “bundle install” as
a post-install script. This takes care of everything. The only thing I am missing
is that the dependencies are visible when inspecting the gem.

RubyGems post_install is not scripts, perhaps you’re using extension
compilation to make that happen, which is intrusive to the user.

You’re also bringing Bundler when the user might not want it into the
mix and slowing down the gem loading process.

Bundler is awesome for development, but is awful for runtime
dependency. You should not be imposing bundler to the user and even
less for runtime execution.

Also bundler do not handle properly all the platforms, using a
different concept of “platform” of what RubyGems understand and is
widely known.

6

On Jan 29, 8:16am, Jarmo P. [email protected] wrote:

You can display a post_install message after you installed “mylib”
that tells:

mylib depends on platform specific components, please install “mylib-
windows” before you start using it.

And still rescue on the LoadError.

The other way around is what I mentioned, but then you will need to
generate one gem for every RubyGems platform: linux, darwin, freebsd,
mingw32, mswin32, etc and indicate the proper dependencies.

Even if the gem itself is not different.

I feel that is more work to do, don’t you think?

7

On Jan 30, 8:06am, Uwe K. [email protected] wrote:

RubyGems post_install is not scripts, perhaps you’re using extension
compilation to make that happen, which is intrusive to the user.

You are right, I use the extension compilation to run the extra install step.

How is this intrusive?

If user grant RubyGems sudo to install the gem and it’s dependencies,
you’re sneaking something that the user was not aware of.

If the user using a gem list find this gem he didn’t install, on
uninstallation no dependency warning will be triggered, and the
original gem will not work because of that.

You’re also bringing Bundler when the user might not want it into the
mix and slowing down the gem loading process.

I would rather add Bundler than not have the gem install all its dependencies.
The user experience is what matters, and this way all dependencies install
correctly and the gem is ready for use regardless of the users platform.

This is similar case to what Hoe did in the past, as add it as
dependency even that you used for development only. Search for it.

Bundler is awesome for development, but is awful for runtime
dependency. You should not be imposing bundler to the user and even
less for runtime execution.

Why not? Bundler is awesome for runtime dependencies as well. It is the default
mechanism for Ruby On Rails runtime dependencies.

Also bundler do not handle properly all the platforms, using a
different concept of “platform” of what RubyGems understand and is
widely known.

The platform concept of Bundler is different from RubyGems platform, but Bundler
handles all platforms properly and the platform concept of Bundler is as well
known and as intuitive as RubyGems.

No, it doesn’t, take for example JSON gem, is broken under 1.9.x or
1.8.x for Windows and even when the user decided to fix it manually,
bundler always force it’s installation.

8

On 2011-01-30, at 19:02, Luis L. wrote:

RubyGems post_install is not scripts, perhaps you’re using extension
compilation to make that happen, which is intrusive to the user.

You are right, I use the extension compilation to run the extra install step.
How is this intrusive?

If user grant RubyGems sudo to install the gem and it’s dependencies,
you’re sneaking something that the user was not aware of.

If the user using a gem list find this gem he didn’t install, on
uninstallation no dependency warning will be triggered, and the
original gem will not work because of that.

True. I consider this a flaw and would very much like to solve that,
too.

You’re also bringing Bundler when the user might not want it into the
mix and slowing down the gem loading process.

I would rather add Bundler than not have the gem install all its dependencies.
The user experience is what matters, and this way all dependencies install
correctly and the gem is ready for use regardless of the users platform.

This is similar case to what Hoe did in the past, as add it as
dependency even that you used for development only. Search for it.

The difference is that Bundler is a good gem for setting up runtime
dependencies. It is not a development only gem.

Bundler is awesome for development, but is awful for runtime
dependency. You should not be imposing bundler to the user and even
less for runtime execution.

Why not? Bundler is awesome for runtime dependencies as well. It is the
default mechanism for Ruby On Rails runtime dependencies.

Good article, and valid if your main concern is application startup
time. My main concerns are ease of installation, and performance after
startup. Bundler fits that need.

Gemfile.lock is generated differently on different platforms · Issue #635 · rubygems/bundler · GitHub
Bundler platforms for Windows are messed up · Issue #589 · rubygems/bundler · GitHub

These are valid concerns, and it looks like they are being taken
seriously, so hopefully they will be sorted out. I appreciate your
efforts on improving Ruby on Windows.

If your gem hits any of these issues, you need to address them, and
maybe using Bundler is not your solution. If your gem does not hit
these issues, maybe you accept your gem will not be used on Windows,
Bundler is a solution to the original problem of having a valid set of
gems installed with your gem without the user having to do extra steps.

I would like to hear other solutions than using Bundler that enables the
correct installation of dependent gems that vary with the user’s
platform.

–
With kind regards
Uwe K.
Kubosch Consulting
[email protected]

9

On 2011-01-29, at 18:55, Luis L. wrote:

I need to build a gem whose dependencies are dependent of the platform
itself. For example when gem install my_gem is issued under Windows,
then in gemspec i have to have spec.add_dependency(“gemX”), but if the
command is executed under linux then i need to have
spec.add_dependency(“gemY”).

I have solved this by making the gem depend on the “bundler” gem, and then put
the gem dependecies into a Gemfile, and run the equivalent of “bundle install” as
a post-install script. This takes care of everything. The only thing I am
missing is that the dependencies are visible when inspecting the gem.

RubyGems post_install is not scripts, perhaps you’re using extension
compilation to make that happen, which is intrusive to the user.

You are right, I use the extension compilation to run the extra install
step.

How is this intrusive?

You’re also bringing Bundler when the user might not want it into the
mix and slowing down the gem loading process.

I would rather add Bundler than not have the gem install all its
dependencies. The user experience is what matters, and this way all
dependencies install correctly and the gem is ready for use regardless
of the users platform.

Bundler is awesome for development, but is awful for runtime
dependency. You should not be imposing bundler to the user and even
less for runtime execution.

Why not? Bundler is awesome for runtime dependencies as well. It is
the default mechanism for Ruby On Rails runtime dependencies.

Also bundler do not handle properly all the platforms, using a
different concept of “platform” of what RubyGems understand and is
widely known.

The platform concept of Bundler is different from RubyGems platform, but
Bundler handles all platforms properly and the platform concept of
Bundler is as well known and as intuitive as RubyGems.

If RubyGems alone would allow developers to solve the problem of
dependencies varying with the user’s platform, that is what I would use.
As long as RubyGems falls short to solve the problem, we need to solve
it some other way. Using Bundler solves the problem, and does it
nicely.

–
With kind regards
Uwe K.
Kubosch Consulting
[email protected]