### Author:  [@Nospam5](https://rubytalk.org/u/Nospam5)
#### Post date: [8 June 2004 20:28 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/4 "2004-06-08T20:28:52Z")
Sean O'Dell wrote:
> Ruby/Interface 0.1-1
Very nice!
But wouldn't implements\_interface(...) instead of declare\_interface(...) be better, e.g "implements" is the Java terminology for implementing an interface? And maybe also implements\_interface?(...) instead of has\_interface?(...). Of aliasses for both.
Regards,
Peter
---
### Author:  [@Gavin\_Sinclair](https://rubytalk.org/u/Gavin_Sinclair)
#### Post date: [8 June 2004 23:40 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/5 "2004-06-08T23:40:24Z")
Nice. But the Hash example on the page should be more comprehensive.
It's ironic that this was driven by wanting to tell an array from a
hash, and you've defined a :hash interface with just and = !
Gavin
> **···**
>
> On Wednesday, June 9, 2004, 4:46:30 AM, Sean wrote:
>
> > Ruby/Interface 0.1-1
>
> > Homepage/Documentation: [http://interface.rubyforge.org/](http://interface.rubyforge.org/)
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [9 June 2004 01:00 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/6 "2004-06-09T01:00:49Z")
Changed the name of the library to [celsoft.com/interface](http://celsoft.com/interface).
Sean O'Dell
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [9 June 2004 19:55 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/7 "2004-06-09T19:55:34Z")
I decided the library wasn't "Ruby" enough and I got some ideas from Daniel
Berger's interface library, so I made a lot of changes.
Homepage: [http://interface.rubyforge.org/](http://interface.rubyforge.org/)
Rubyforge Project Homepage: [http://rubyforge.org/projects/interface/](http://rubyforge.org/projects/interface/)
Download: [http://rubyforge.org/frs/?group\_id=266&release\_id=529](http://rubyforge.org/frs/?group_id=266&release_id=529)
Code Snippet:
require "[celsoft.com/interface](http://celsoft.com/interface)"
HashInterface = Interface.new
HashInterface.add\_class\_patterns(Hash, :[], :[]=)
HashInterface.add\_pattern(:each\_pair, proc{||})
class Hash
implements HashInterface
end
class\<\
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [8 June 2004 20:50 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/8 "2004-06-08T20:50:46Z")
I have to ponder this a bit. I admit I am not entirely clear how Ruby works
internally, and singletons are something I don't quite get. Let me digest
the suggestions.
Sean O'Dell
> **···**
>
> On Tuesday 08 June 2004 13:23, Mauricio Fernández wrote:
>
> > On Wed, Jun 09, 2004 at 03:46:30AM +0900, Sean O'Dell wrote:
> > \> Ruby/Interface tries to solve this problem by ???tagging??? objects as
> > \> implementing an interface. The implementation is enforced by comparing an
> > \> object???s methods against the methods expected by the interface.
> >
> > Some comments:
> >
> > I see you're using per-class tagging, hence being unable to track
> > changes in the singleton class. I'd point you again to the last sections
> > of [http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/102555](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/102555)
> > which I believe you didn't read.
> > There's an inconsistency in the code: you're checking the methods of the
> > object (including its singleton methods) with Object#method but storing
> > the result in a per-class structure; that won't fly.
> >
> > Also, using class variables instead of class instance variables ties the
> > notion of interface to inheritance, which I believe you wanted to avoid.
> >
> > I would consider storing the conformance information in
> > ROBJECT(self)-\>klass directly; this will be either the real class or
> > the singleton class. In the first case, the "conformity table" is
> > shared by all objects of that class; in the second, it will be "owned"
> > by the object. The advantage is that this new table would be created
> > on demand, only when the object is extended/a singleton method is
> > defined and has\_interface? is called. You wouldn't even need to capture
> > singleton\_method\_added this way.
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [8 June 2004 20:51 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/9 "2004-06-08T20:51:33Z")
Probably right. I'll change it. Seems I'm going to be fiddling it with it
some more today anyway, may as well take of that now!
Sean O'Dell
> **···**
>
> On Tuesday 08 June 2004 13:28, Peter C. Verhage wrote:
>
> > Sean O'Dell wrote:
> > \> Ruby/Interface 0.1-1
> >
> > Very nice!
> >
> > But wouldn't implements\_interface(...) instead of declare\_interface(...)
> > be better, e.g "implements" is the Java terminology for implementing an
> > interface? And maybe also implements\_interface?(...) instead of
> > has\_interface?(...). Of aliasses for both.
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [8 June 2004 21:13 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/10 "2004-06-08T21:13:29Z")
> \> Ruby/Interface tries to solve this problem by ???tagging??? objects as
> \> implementing an interface. The implementation is enforced by comparing an
> \> object???s methods against the methods expected by the interface.
>
> Some comments:
>
> I see you're using per-class tagging, hence being unable to track
> changes in the singleton class. I'd point you again to the last sections
> of [http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/102555](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/102555)
> which I believe you didn't read.
Per-class tagging is what I intended. There are three tag states: not tagged,
tagged but unverified, and tagged and verified. Tagging initially only means
"objects of this class may implement this interface." A check of the object
itself later will determine if the object really does implement the
interface.
> There's an inconsistency in the code: you're checking the methods of the
> object (including its singleton methods) with Object#method but storing
> the result in a per-class structure; that won't fly.
I see what you mean. I need to move the storage of the checks themselves to
the object, absolutely correct. I think what I was thinking when I did it
this way was, since I get no "module\_added" messages when methods are added
to objects with \<\<, there was no sense in storing the information with the
objects themselves. But I see that there's an inconsistency that way. I'll
change that.
> Also, using class variables instead of class instance variables ties the
> notion of interface to inheritance, which I believe you wanted to avoid.
No, not necessarily. Classes derived from other classes should inherit the
interface. The initial tag only means "may implement the interface" not
"does implement it." The final test is a comparison of the methods of the
individual object methods and their arity.
> I would consider storing the conformance information in
> ROBJECT(self)-\>klass directly; this will be either the real class or
> the singleton class. In the first case, the "conformity table" is
> shared by all objects of that class; in the second, it will be "owned"
> by the object. The advantage is that this new table would be created
> on demand, only when the object is extended/a singleton method is
> defined and has\_interface? is called. You wouldn't even need to capture
> singleton\_method\_added this way.
Ah, I see...thanks for pointing me at this. I was never really aware of klass
before. I just read about how it relates to Singleton's, and it gave a whole
heap of ideas on how I could do this better.
Sean O'Dell
Sean O'Dell
> **···**
>
> On Tuesday 08 June 2004 13:23, Mauricio Fernández wrote:
>
> > On Wed, Jun 09, 2004 at 03:46:30AM +0900, Sean O'Dell wrote:
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [8 June 2004 22:54 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/11 "2004-06-08T22:54:39Z")
Moving things around to work out of klass helped a lot, Mauricio, thanks for
the advice. Got a new version up and running already. It handles Singletons
nicely now.
Sean O'Dell
> **···**
>
> On Tuesday 08 June 2004 13:23, Mauricio Fernández wrote:
>
> > On Wed, Jun 09, 2004 at 03:46:30AM +0900, Sean O'Dell wrote:
> > \> Ruby/Interface tries to solve this problem by ???tagging??? objects as
> > \> implementing an interface. The implementation is enforced by comparing an
> > \> object???s methods against the methods expected by the interface.
> >
> > Some comments:
> >
> > I see you're using per-class tagging, hence being unable to track
> > changes in the singleton class. I'd point you again to the last sections
> > of [http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/102555](http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/102555)
> > which I believe you didn't read.
> > There's an inconsistency in the code: you're checking the methods of the
> > object (including its singleton methods) with Object#method but storing
> > the result in a per-class structure; that won't fly.
> >
> > Also, using class variables instead of class instance variables ties the
> > notion of interface to inheritance, which I believe you wanted to avoid.
> >
> > I would consider storing the conformance information in
> > ROBJECT(self)-\>klass directly; this will be either the real class or
> > the singleton class. In the first case, the "conformity table" is
> > shared by all objects of that class; in the second, it will be "owned"
> > by the object. The advantage is that this new table would be created
> > on demand, only when the object is extended/a singleton method is
> > defined and has\_interface? is called. You wouldn't even need to capture
> > singleton\_method\_added this way.
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [9 June 2004 00:11 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/12 "2004-06-09T00:11:02Z")
The name :hash tells you the purpose of the interface, not the method list.
The method list is just to aid enforcement (to ensure they exist for the
interface, and to ensure they have the same parameters so you can always
depend on them being there as you expect them).
.has\_interface?(:hash) =\> false
Make sense?
Sean O'Dell
> **···**
>
> On Tuesday 08 June 2004 16:40, Gavin Sinclair wrote:
>
> > On Wednesday, June 9, 2004, 4:46:30 AM, Sean wrote:
> > \> Ruby/Interface 0.1-1
> > \>
> > \> Homepage/Documentation: [http://interface.rubyforge.org/](http://interface.rubyforge.org/)
> >
> > Nice. But the Hash example on the page should be more comprehensive.
> > It's ironic that this was driven by wanting to tell an array from a
> > hash, and you've defined a :hash interface with just and = !
---
### Author:  [@David\_A\_Black3](https://rubytalk.org/u/David_A_Black3)
#### Post date: [9 June 2004 01:06 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/13 "2004-06-09T01:06:43Z")
Hi --
> **···**
>
> On Wed, 9 Jun 2004, Sean O'Dell wrote:
>
> > Changed the name of the library to celsoft.com/interface.
>
> Ignore previous message (similar idea in spirit though
> flipped the other way) -- hadn't seen this one.
>
> David
>
> --
> David A. Black
> dblack@wobblini.net
---
### Author:  [@Mauricio\_Fernndez](https://rubytalk.org/u/Mauricio_Fernndez)
#### Post date: [9 June 2004 20:23 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/14 "2004-06-09T20:23:02Z")
You might want to capture Module#remove\_method and
Module#undef\_method...
> **···**
>
> On Thu, Jun 10, 2004 at 04:55:34AM +0900, Sean O'Dell wrote:
>
> > If either the interface definition changes, or methods are
> > changed in the class of the object, the cache is dumped and the thorough
> > check is performed the next time implements? is called, and the answer is
> > then again cached.
>
> --
> Running Debian GNU/Linux Sid (unstable)
> batsman dot geo at yahoo dot com
>
> > Linux is not user-friendly.
>
> It \_is\_ user-friendly. It is not ignorant-friendly and idiot-friendly.
> -- Seen somewhere on the net
---
### Author:  [@Jean-Hugues\_ROBERT](https://rubytalk.org/u/Jean-Hugues_ROBERT)
#### Post date: [10 June 2004 08:28 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/15 "2004-06-10T08:28:00Z")
> I decided the library wasn't "Ruby" enough and I got some ideas from Daniel
> Berger's interface library, so I made a lot of changes.
>
> Homepage: [http://interface.rubyforge.org/](http://interface.rubyforge.org/)
> Rubyforge Project Homepage: [http://rubyforge.org/projects/interface/](http://rubyforge.org/projects/interface/)
> Download: [http://rubyforge.org/frs/?group\_id=266&release\_id=529](http://rubyforge.org/frs/?group_id=266&release_id=529)
>
> Code Snippet:
>
> require "celsoft.com/interface"
>
> HashInterface = Interface.new
>
> HashInterface.add\_class\_patterns(Hash, :, :=)
> HashInterface.add\_pattern(:each\_pair, proc{||})
>
> class Hash
> implements HashInterface
> end
>
> class\<\ implements HashInterface
> end
>
> p Hash.new.implements?(HashInterface) == true
> p ENV.implements?(HashInterface) == true
Should be implement?() vs implements?() I believe.
See include?() for example.
That is a nice Ruby idiom.
Also: You are using both "declarative" (like "implements")
and "imperative" styles (like "add\_pattern). I feel like
"declarative" style would be appropriate in both cases.
OTOH that might be a matter of style/taste.
Yours,
JeanHuguesRobert
EOM
> **···**
>
> At 04:55 10/06/2004 +0900, you wrote:
>
> > HashInterface.add\_pattern(:each\_pair, proc{|a|}) # method param changed
> >
> > p ENV.implements?(HashInterface) == false
> >
> > How It Works
> >
> > Method patterns are stored with each Interface object and are used to check
> > against the methods of any given object. The name and number of parameters
> > are important. If an object never claims to implement an interface, it will
> > always report that it does not implement a given interface, even if it may be
> > capable of it. When an object claims to implement an interface, a thorough
> > check is performed to verify that it actually does. This check is only
> > performed when necessary for efficiency, when implements? is called. The
> > result of the check is cached and returned quickly on subsequent calls to
> > implements?. If either the interface definition changes, or methods are
> > changed in the class of the object, the cache is dumped and the thorough
> > check is performed the next time implements? is called, and the answer is
> > then again cached.
>
> -------------------------------------------------------------------------
> Web: [@jhr is virteal, virtually real](http://hdl.handle.net/1030.37/1.1)
> Phone: +33 (0) 4 92 27 74 17
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [10 June 2004 15:33 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/16 "2004-06-10T15:33:17Z")
> Should be implement?() vs implements?() I believe.
> See include?() for example.
> That is a nice Ruby idiom.
It's not proper English, but perhaps implement? is more "Ruby."
> Also: You are using both "declarative" (like "implements")
> and "imperative" styles (like "add\_pattern). I feel like
> "declarative" style would be appropriate in both cases.
On this I totally agree, except for one thing. Since I can't do:
interface IHash
pattern (key)
end
...to create the interface (like class or module) I don't feel like
declarative is the way to go. I have no choice but to build interface
procedurally, so I felt that more action-oriented methods were better.
I think if Matz ever gives developers the ability to do what I did above
there, I would switch to something more declarative.
Sean O'Dell
> **···**
>
> On Thursday 10 June 2004 01:28, Jean-Hugues ROBERT wrote:
>
> > At 04:55 10/06/2004 +0900, you wrote:
---
### Author:  [@Mark\_Hubbart](https://rubytalk.org/u/Mark_Hubbart)
#### Post date: [10 June 2004 17:57 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/17 "2004-06-10T17:57:57Z")
After being annoyed with what looked like improper English in
all those #foo? methods, I noticed that you could read them as, say, "does foo include?" or "does foo respond\_to?" etc... They make sense that way, and are proper English, inasmuch as any programming construct is proper English 🙂
cheers,
Mark
> **···**
>
> On Jun 10, 2004, at 8:33 AM, Sean O'Dell wrote:
>
> > On Thursday 10 June 2004 01:28, Jean-Hugues ROBERT wrote:
> >
> > > At 04:55 10/06/2004 +0900, you wrote:
> > >
> > > Should be implement?() vs implements?() I believe.
> > > See include?() for example.
> > > That is a nice Ruby idiom.
> >
> > It's not proper English, but perhaps implement? is more "Ruby."
---
### Author:  [@Sean\_O\_Dell1](https://rubytalk.org/u/Sean_O_Dell1)
#### Post date: [10 June 2004 18:57 UTC](https://rubytalk.org/t/ann-ruby-interface/11998/18 "2004-06-10T18:57:19Z")
Interesting way to look at it.
Running my eyes over a lot of Ruby methods, I can see that implement? is more
correct. However, I noticed that some methods are has\_ or is\_ prepended to
them. I guess when does\_ makes more sense, the rule is to eliminate it?
Either way, I see the pattern and I prefer the library behave the way people
"expect" so I'll change the method names.
Just a side-note: I've added pre-defined interfaces for IArray, IHash,
IString, IDate and ITime so far. 0.6 will have ITime and IDate and whatever
others I add. 0.5 already has those others.
Sean O'Dell
> **···**
>
> On Thursday 10 June 2004 10:57, Mark Hubbart wrote:
>
> > On Jun 10, 2004, at 8:33 AM, Sean O'Dell wrote:
> > \> On Thursday 10 June 2004 01:28, Jean-Hugues ROBERT wrote:
> > \>\> At 04:55 10/06/2004 +0900, you wrote:
> > \>\>
> > \>\> Should be implement?() vs implements?() I believe.
> > \>\> See include?() for example.
> > \>\> That is a nice Ruby idiom.
> > \>
> > \> It's not proper English, but perhaps implement? is more "Ruby."
> >
> > After being annoyed with what looked like improper English in
> > all those #foo? methods, I noticed that you could read them as, say,
> > "does foo include?" or "does foo respond\_to?" etc... They make sense
> > that way, and are proper English, inasmuch as any programming construct
> > is proper English 🙂