[lnkForumImage]
TotalShareware - Download Free Software
Confronta i prezzi di migliaia di prodotti.
Asp Forum
 Home | Login | Register | Search 


 

Forums >

comp.lang.ruby

Exception naming conventions: rely on module name?

Edwin Fine

12/29/2006 5:50:00 PM

I am wondering about design alternatives regarding exception naming in
Ruby. Is there a naming convention for exceptions that are declared
inside a module?

For example, let's say we have a module named MP3, and we want to have a
base exception for MP3-related errors. There are two basic choices I am
considering here:

module MP3
class MP3Error < StandardError; end # Alternative 1
class Error < StandardError; end # Alternative 2
end

Outside the module, Error would be disambiguated by MP3 (MP3::Error).
However, I am uneasy about this, because of the following situation.
Imagine someone has some existing code that mixes in module Other:

module Other
class Error < StandardError; end
end

class Foo
include Other
def Foo.oops
raise Error, "Who am I?"
rescue Error => e
puts "#{e} #{e.class.name}"
end
end

Foo.oops # Who am I? Other::Error

Now this hapless person mixes in MP3.

class Foo
include Other
include MP3
def Foo.oops
raise Error, "Who am I?"
rescue Error => e
puts "#{e} #{e.class.name}"
end
end

Foo.oops # Who am I? MP3::Error

- Is this a real concern?
- Do you think it would be better to have exception names that are less
likely to clash at the cost of some duplication (e.g. MP3::MP3Error
instead of MP3::Error)?

--
Posted via http://www.ruby-....
2 Answers

Eric Hodel

12/29/2006 9:39:00 PM

0

On Dec 29, 2006, at 09:50, Edwin Fine wrote:

> I am wondering about design alternatives regarding exception naming in
> Ruby. Is there a naming convention for exceptions that are declared
> inside a module?
>
> For example, let's say we have a module named MP3, and we want to
> have a base exception for MP3-related errors. There are two basic
> choices I am considering here:
>
> module MP3
> class MP3Error < StandardError; end # Alternative 1
> class Error < StandardError; end # Alternative 2
> end

I typically use #2

> Outside the module, Error would be disambiguated by MP3 (MP3::Error).
> However, I am uneasy about this, because of the following situation.
> Imagine someone has some existing code that mixes in module Other:
>
> module Other
> class Error < StandardError; end
> end
>
> class Foo
> include Other
> def Foo.oops
> raise Error, "Who am I?"
> rescue Error => e
> puts "#{e} #{e.class.name}"
> end
> end
>
> Foo.oops # Who am I? Other::Error

Always fully qualify.

> Now this hapless person mixes in MP3.
>
> class Foo
> include Other
> include MP3
> def Foo.oops
> raise Error, "Who am I?"
> rescue Error => e
> puts "#{e} #{e.class.name}"
> end
> end
>
> Foo.oops # Who am I? MP3::Error
>
> - Is this a real concern?

No. Fully qualify and it won't be a problem.

> - Do you think it would be better to have exception names that are
> less likely to clash at the cost of some duplication (e.g.
> MP3::MP3Error instead of MP3::Error)?

MP3::MP3Error is redundant. There is no problem if you raise
MP3::Error instead. If a consumer of your library decides to omit
Error that's their bug, not yours.

--
Eric Hodel - drbrain@segment7.net - http://blog.se...

I LIT YOUR GEM ON FIRE!

Edwin Fine

12/30/2006 3:59:00 AM

0

Eric Hodel wrote:

> MP3::MP3Error is redundant. There is no problem if you raise
> MP3::Error instead. If a consumer of your library decides to omit
> Error that's their bug, not yours.
>
> --
> Eric Hodel - drbrain@segment7.net - http://blog.se...
>
> I LIT YOUR GEM ON FIRE!

Thank you for your advice. I will follow it.
Ed