Getting Gem Version from Within a Gem

[Frew Schmidt]

Does anyone know if there is a way that I can have my program output
what version it is and get the version from the Gem that it is installed
from?

Thanks!
-fREW

 

[Kuba]

Does anyone know if there is a way that I can have my program output
what version it is and get the version from the Gem that it is installed
from?

Using 'gem' , you can execute sth. like:

gem list --local | grep <your_prog_name>

but i'm not sure, is it what you expect.

Best Regards, Kuba.

 

[Frew Schmidt]

Using 'gem' , you can execute sth. like:

gem list --local | grep <your_prog_name>

but i'm not sure, is it what you expect.

Best Regards, Kuba.

So there's not a variable inside the program that I can access that
contains the Gem info?

 

[Frew Schmidt]

Frew,

The usual method of accessing the version of a gem from within a
running Ruby app is:

GemConstName::Version::STRING

This works if the author followed convention.

I am the author of the application in question. I tested your
suggestion by doing a

to see if it would have the variable defined by the gem system as
defined in my gemspec, but it didn't work. Is there something I need to
do to make this work?

Thanks for your help!

-fREW

 

[Kuba Podgorski]

So there's not a variable inside the program that I can access that
contains the Gem info?

I think, it depends on your gems' library/program.
There is no general variable (fix me if i'm wrong).

E.g.: In module 'Inline' is defined const. VERSION, so you can print
Inline::VERSION, but 'rake' defined const. RAKEVERSION

 

[Frew Schmidt]

E.g.: In module 'Inline' is defined const. VERSION, so you can print

Inline::VERSION, but 'rake' defined const. RAKEVERSION

So what I really need to do here is define a constant in a separate file
as a module and include it in the gemspec and my other code. Is that
correct?

 

[Frew Schmidt]

Thanks for your help!

Frew, why yes there is!!! Thank you for clarifying the question. Tis
simple!

In lib/gem_name/version.rb place code like:
=================================
module GemName
module Version
# A method for comparing versions of required modules. It
expects two
# arrays as parameters, and returns true if the first is no more
than the
# second.
def self.check(expected, actual) #:nodoc:
good = false
if actual[0] > expected[0]
good = true
elsif actual[0] == expected[0]
if actual[1] > expected[1]
good = true
elsif actual[1] == expected[1] && actual[2] >= expected[2]
good = true
end
end

good
end

MAJOR = 0
MINOR = 1
TINY = 2

STRING = [MAJOR, MINOR, TINY].join(".")

SSH_REQUIRED = [1,0,10]
SFTP_REQUIRED = [1,1,0]
end
end
=================================

Then require the version file in one of the main entry point files:

require "lib/gem_name/version"

Hope this helps! Gems are so much fun to develop.

Ok, I want to ensure that I am doing this the correct way, so is this
right?

lib/delish/version.rb
=====================
module Delish

module Version
MAJOR = 0
MINOR = 7
TINY = 9

STRING = [MAJOR, MINOR, TINY].join(".")
end

end
=====================

 

[Frew Schmidt]

Looks correct to me. You still might want to provide the check method

as it provides an interface for versioning checks.

So now you should be able to report the version from within your app
via:
Delish::Version::STRING

So if I did end up using the check method would I do something like this


Delish::Version::check(GTK::Version, Delish::Version::GTK_VERSION)
# Some gtk code here

Or something like that?

What's the use of this if the gemspec already has dependencies like
this?

Thanks again for your help!

-fREW

 

[Eric Hodel]

Ok, I want to ensure that I am doing this the correct way, so is this
right?

lib/delish/version.rb
=====================
module Delish

module Version
MAJOR = 0
MINOR = 7
TINY = 9

STRING = [MAJOR, MINOR, TINY].join(".")
end

end

UGH!

KISS, or employ YAGNI.

module Delish

VERSION = '0.7.9'

end

You don't need major/minor/tiny.

 

[Eric Hodel]

Does anyone know if there is a way that I can have my program output
what version it is and get the version from the Gem that it is
installed
from?

Gem.loaded_specs.map do |n,s| s.full_name end

Better to just have a VERSION constant somewhere, though.

 

[Ryan Davis]

Does anyone know if there is a way that I can have my program output
what version it is and get the version from the Gem that it is
installed
from?

invert!

Have your program know what its version is and have your gemspec ask it:

=== lib/blah.rb

class Blah
VERSION = "1.2.3"
# ...
end

=== Rakefile

require 'rubygems'
require 'hoe'

require './lib/blah.rb'

Hoe.new("Blah", Blah::VERSION) do |p| # this builds the gemspec and
defines a lot of commands
# ...
end