# Autoloader, version 0.0.2

**URL:** <https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402>\
**Category:** Ruby\
**Created:** [November 24, 2009, 6:36am UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402 "2009-11-24T06:36:18Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 24, 2009, 6:36am UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/1 "2009-11-24T06:36:18Z")

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A couple of handy features to enhance Kernel#autoload.

Changes since 0.0.1: minor tweaks to the gem, and migrated to gemcutter.

Question: How do I add a choice of dependencies? Right now, I can use  
either  
extlib or activesupport for inflections.

Also: This is my first ever ruby-talk announcement. Someone please tell  
me if  
I am Doing It Wrong.

Pasted from the README:

# Features

- Fire Kernel#autoload at an entire directory
- Fire it again at a subdirectory, for namespace’d models

# Motivation/Examples

I was using Ramaze as a web framework, and discovered that the standard  
Ramaze  
way of loading a directory of files is to slurp them all (with  
‘acquire’). I  
decided I’d rather use autoload, and not load things I’m not using. But  
I  
wasn’t really looking forward to this:

autoload :User, ‘model/user’  
autoload :Clan, ‘model/clan’  
autoload :Item, ‘model/item’

…ad nauseum. So, the first feature is a shallow, directory-based  
autoload:

AutoLoader \<\< ‘model’

Of course, being a pedant, I like to namespace my models. I don’t want  
to  
slurp the entire directory tree. Instead, you can do this:

class User \< MyFavoriteORM::Model  
include AutoLoader  
…  
end

Now, all AutoLoaded paths will be searched for a subdirectory called  
‘user’,  
and all files within will be autoloaded. Just as if you’d done:

User.autoload :Anonymous, ‘model/user/anonymous’  
User.autoload :Registered, ‘model/user/registered’

Of course, there’s no requirement that you have a base class, or  
anything of  
the sort. If you just want a namespace, you can always do:

module MyNamespace; include AutoLoader; end

And you’re done.

# Compatibility

Currently, Merb’s extlib and Rails’ activesupport are supported. It  
should be  
trivial to interface with other libraries.

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<div class="post-metadata">

**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 24, 2009, 1:48pm UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/2 "2009-11-24T13:48:12Z")

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2009/11/24 David M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> A couple of handy features to enhance Kernel#autoload.
> 
> Changes since 0.0.1: minor tweaks to the gem, and migrated to gemcutter.
> 
> Question: How do I add a choice of dependencies? Right now, I can use either  
> extlib or activesupport for inflections.
> 
> Also: This is my first ever ruby-talk announcement. Someone please tell me if  
> I am Doing It Wrong.

Looks fine to me. But I do wonder how you generate the symbol names  
for autoload files? Basically autoload needs a symbol name and a file  
name. While the file names can be extracted from a directory how do  
you find the symbol name? Maybe users should be able to customize  
that algorithm in order to be able to autoload class “FooBar” from  
file “foobar.rb” or “foo\_bar.rb”. I would at least add a description  
how you generate the symbol name from the file name.

Btw, one disadvantage of using a directory glob is that it is far more  
expensive than the standard autoload because the standard autoload  
does not need any file system IO before any file is loaded. Using  
directory globbing on the other hand requires to at least read the  
directory which may slow down startup of a script considerably.

Kind regards

robert

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**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 24, 2009, 3:16pm UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/3 "2009-11-24T15:16:35Z")

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On Tue, Nov 24, 2009 at 12:34 AM, David M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> A couple of handy features to enhance Kernel#autoload.
> 
> Changes since 0.0.1: minor tweaks to the gem, and migrated to gemcutter.
> 
> Question: How do I add a choice of dependencies? Right now, I can use either  
> extlib or activesupport for inflections.

As far as I know, you can’t.

I’ve got a similar situation with ri\_cal which needs either  
activesupport or tzinfo. I asked about this on the rubygems list and  
alternate dependencies seemed to be something which had come up from  
time to time but hadn’t been addressed.

I just didn’t declare either as a dependency and rely on documentation  
to let users know that they need one or the other.

–  
Rick DeNatale

Blog: [http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/)  
Twitter: [http://twitter.com/RickDeNatale](http://twitter.com/RickDeNatale)  
WWR: [http://www.workingwithrails.com/person/9021-rick-denatale](http://www.workingwithrails.com/person/9021-rick-denatale)  
LinkedIn: [http://www.linkedin.com/in/rickdenatale](http://www.linkedin.com/in/rickdenatale)

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**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 24, 2009, 7:09pm UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/4 "2009-11-24T19:09:33Z")

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On Tuesday 24 November 2009 06:43:20 am Robert K. wrote:

> Looks fine to me. But I do wonder how you generate the symbol names  
> for autoload files? Basically autoload needs a symbol name and a file  
> name. While the file names can be extracted from a directory how do  
> you find the symbol name?

More or less the same way Rails does, which is why I support these  
various  
inflection libraries. Basically, I take the file name and munge it so it  
looks  
like a constant name.

> Maybe users should be able to customize  
> that algorithm in order to be able to autoload class “FooBar” from  
> file “foobar.rb” or “foo\_bar.rb”.

Right now, it’s specified to be foo\_bar.rb. It uses  
String#to\_const\_string  
from extlib, or String#camelize from ActiveSupport. If neither of these  
are  
loaded, it tries to load extlib, then activesupport/inflector.

Maybe users should be able to customize it. The idea is, of course,  
convention  
over configuration. If there’s only a single exception (FooBar, for  
example),  
you could always manually autoload that one file.

> I would at least add a description  
> how you generate the symbol name from the file name.

Neither of these are bad ideas.

If you can think of a way to customize the behavior without  
overcomplicating  
things, go for it. I’m not motivated, so patches welcome.

> Btw, one disadvantage of using a directory glob is that it is far more  
> expensive than the standard autoload because the standard autoload  
> does not need any file system IO before any file is loaded. Using  
> directory globbing on the other hand requires to at least read the  
> directory which may slow down startup of a script considerably.

Except that standard autoload is more work for me, and nearly defeats  
the  
point. Trading requires for autoloads directly makes things harder to  
debug  
without making them easier to write – it _only_ optimizes start time.

One possibility would be to write a script which attempts to  
automatically  
generate these autoload statements, but store them statically in a  
single  
file. The main reason I don’t like that is, you’ve now added a “compile”  
step  
to a script. It might work as an option, maybe a “development” vs  
“production”  
mode.

Another possibility is to override const\_missing, but that gets complex  
fast,  
as Rails shows.

Also, keep in mind that the directory IO is shallow. That is, if you  
tell it  
to autoload foo, it won’t touch anything in foo/bar. If you create a  
file  
bar.rb which requires autoload, it will look at foo/bar, but only once  
Bar is  
autoloaded.

Thanks for the feedback!

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**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 24, 2009, 11:26pm UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/5 "2009-11-24T23:26:30Z")

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On 11/24/2009 07:06 PM, David M. wrote:

> On Tuesday 24 November 2009 06:43:20 am Robert K. wrote:

> > Btw, one disadvantage of using a directory glob is that it is far more  
> > expensive than the standard autoload because the standard autoload  
> > does not need any file system IO before any file is loaded. Using  
> > directory globbing on the other hand requires to at least read the  
> > directory which may slow down startup of a script considerably.
> 
> Except that standard autoload is more work for me, and nearly defeats the  
> point. Trading requires for autoloads directly makes things harder to debug  
> without making them easier to write – it _only_ optimizes start time.

Yeah, absolutely. If your major goal is to simplify script writing this  
is definitive a good option. I just wanted to point out that the  
convenience comes at a price. 🙂

> One possibility would be to write a script which attempts to automatically  
> generate these autoload statements, but store them statically in a single  
> file. The main reason I don’t like that is, you’ve now added a “compile” step  
> to a script. It might work as an option, maybe a “development” vs “production”  
> mode.

Yeah, ugly.

> Another possibility is to override const\_missing, but that gets complex fast,  
> as Rails shows.
> 
> Also, keep in mind that the directory IO is shallow. That is, if you tell it  
> to autoload foo, it won’t touch anything in foo/bar. If you create a file  
> bar.rb which requires autoload, it will look at foo/bar, but only once Bar is  
> autoloaded.
> 
> Thanks for the feedback!

You’re welcome! Thanks for taking the time to digest it.

Kind regards

robert

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**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 25, 2009, 3:37am UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/6 "2009-11-25T03:37:01Z")

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On Tuesday 24 November 2009 04:21:03 pm Robert K. wrote:

> > debug without making them easier to write – it _only_ optimizes start  
> > time.
> 
> Yeah, absolutely. If your major goal is to simplify script writing this  
> is definitive a good option. I just wanted to point out that the  
> convenience comes at a price. 🙂

Well, I want a sane balance. I want to optimize start time to where an  
app  
starts in under a second, versus thirty seconds – and I think I’ve done  
that  
without much additional complexity.

In other words, I think it’s the best of both worlds.

If I _only_ wanted to simplify script writing, Ramaze has a much simpler  
solution – they’ve defined Kernel#acquire, which requires every .rb  
file in a  
given directory tree. That’s easier to write and easier to use, but as  
an app  
gets bigger, it would get slower.

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**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 25, 2009, 9:08am UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/7 "2009-11-25T09:08:51Z")

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I know about some work on merb, it collects depenedencies, then tries to  
load them in diffirent order, and sees which one ends properly, AFAIK  
there’s no way to define alternative dependencies

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**Author:** ![dgm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/df788c/32.png) [@dgm](https://www.ruby-forum.com/u/dgm)\
**Post date:** [November 25, 2009, 6:40pm UTC](https://www.ruby-forum.com/t/autoloader-version-0-0-2/179402/8 "2009-11-25T18:40:39Z")

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On 25.11.2009 03:36, David M. wrote:

> > > debug without making them easier to write – it _only_ optimizes start  
> > > time.  
> > > Yeah, absolutely. If your major goal is to simplify script writing this  
> > > is definitive a good option. I just wanted to point out that the  
> > > convenience comes at a price. 🙂
> 
> Well, I want a sane balance.

Fair enough.

> I want to optimize start time to where an app  
> starts in under a second, versus thirty seconds – and I think I’ve done that  
> without much additional complexity.

Well, that sounds like a successful optimization operation. 🙂

> In other words, I think it’s the best of both worlds.
> 
> If I _only_ wanted to simplify script writing, Ramaze has a much simpler  
> solution – they’ve defined Kernel#acquire, which requires every .rb file in a  
> given directory tree. That’s easier to write and easier to use, but as an app  
> gets bigger, it would get slower.

Good pointer! Thanks for sharing.

Cheers

robert