# Rubygems and manually installed dependencies
**URL:** https://rubytalk.org/t/rubygems-and-manually-installed-dependencies/20831
**Category:** ruby-talk
**Created:** [14 September 2005 18:56 UTC](https://rubytalk.org/t/rubygems-and-manually-installed-dependencies/20831 "2005-09-14T18:56:33Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@7rans](https://rubytalk.org/u/7rans)
#### Post date: [14 September 2005 18:56 UTC](https://rubytalk.org/t/rubygems-and-manually-installed-dependencies/20831/1 "2005-09-14T18:56:33Z")
please correct me if i am mistaken. if i'm using a gems installrf app
that has gem dependencies, rubygems will prevent it from working unless
those other gems are installed? even if those other apps are install
manually?
thanks,
t.
---
### Author:  [@Jim\_Weirich1](https://rubytalk.org/u/Jim_Weirich1)
#### Post date: [14 September 2005 19:24 UTC](https://rubytalk.org/t/rubygems-and-manually-installed-dependencies/20831/2 "2005-09-14T19:24:40Z")
Trans said:
> please correct me if i am mistaken. if i'm using a gems installrf app
> that has gem dependencies, rubygems will prevent it from working unless
> those other gems are installed? even if those other apps are install
> manually?
Just to be clear ... there are two kinds of dependencies.
There are the declared dependencies in the gem metadata that are used to
identify additional gems that might be needed at install time. A --force
flag on the gem command will override these declared dependencies and
allow you to install even if the other gems are not available.
The other kind of dependency is a require\_gem statement in the runtime
code. If a require\_gem statement cannot find a gem that matches the name
and requested version constraint, then an exception will be generated.
However, most applications should \*not\* be using require\_gem, even if they
are installed by gems. You should use require\_gem \_only\_ if you wish to
require a particular version of a library.
> **ยทยทยท**
>
> --
> -- Jim Weirich jim@weirichhouse.org [http://onestepback.org](http://onestepback.org)
> -----------------------------------------------------------------
> "Beware of bugs in the above code; I have only proved it correct,
> not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)
---
### Author:  [@7rans](https://rubytalk.org/u/7rans)
#### Post date: [14 September 2005 19:56 UTC](https://rubytalk.org/t/rubygems-and-manually-installed-dependencies/20831/3 "2005-09-14T19:56:35Z")
Thanks Jim,
That's what I thought. But when I was trying to run Nitro, rubygems
reported that nano/mega wasn't installed. But they were manually
installed. When I installed the gems the errors went away. So then I
egrep the nitro gem dir and there is no 'require\_gem'. In fact I
egrepped my enitre gems dir and only Rake has two uses of require\_gem.
So I don't understand.
T.