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Occasionally, you may want to know how a gem functions internally. In this video, we'll see how to look at the contents of a gem.
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Sometimes, as you're coding and using
a gem, you may want to get a better idea
0:00
of how it was written or
take a look at a function or method.
0:05
RubyGems gives us this ability with
a couple of different commands.
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We can see the location of gems and open
them in our editor to see how they work.
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Let's go ahead and
see how that works now using Workspaces.
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So if we want to see the contents of
a gem, we can use the contents command.
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And we pass in the name of the gem.
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So by typing, gem contents money,
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this will list everything that
is inside of the money gem.
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These are all of the different files.
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Authors, change log,
contributing, gem file, etc.
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We can also see all the library
files that make up the money gem.
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The gemspec, which tells Ruby
about the different versions and
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dependencies, and the different tests.
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Let's go ahead and
change to that directory.
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So we can do that by saying,
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cd
/home/treehouse/.local/gems/gems/money-6.-
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6.1.
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And now we are inside of the money gem.
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If we wanted to get a list of how this
works, we could use the ls command,
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and we can see that the only
file listed is money.rb.
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Which requires everything from this
directory inside of the money directory.
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So if we go a little bit further and
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we list the files, we should see that
these should be included as well.
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So we require money/money and
money/currency.
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So if I look at the money.rb file,
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here is the different Ruby code
that makes up the Ruby money gem.
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Now, if we do some syntax
highlighting here with vim,
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we can walk through the money class, and
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see how it's coded if we wanted to
get an idea of how money works.
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So we can see that the cents
method returns a fractional or
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an integer with infinite
precision false or
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big decimal with infinite precision true.
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Now, we're only going to need
to look at this documentation or
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these methods if we need to.
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So if we're writing a program and we come
across something that we don't understand,
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it's very useful to be able to look at the
source code of the gem that we're using.
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Then we can also see this requires
different files inside of the gem.
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So if I wanted to look at
how the formatting worked,
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we could look at the formatting.rb file.
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And we can see how this class is set up.
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For the most part, we don't need to do
this when we're working with gems, but
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it is useful to know where gems
are installed, located, and
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how they're written.
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