Hyphens in variable names

Ruby
1

Hello,

I am new to Ruby and have an issue with a xmlsimple object resulting
from a 3rd party webservice.

The xml has nodes that have hyphens (-) in the names. When I try to
access various hashes using the object variables I get errors telling
that the variable doesn’t exists. I realize that the ruby syntax doesnot
like hyphens in variable names, how do I get around this?

Example XML:

... ...

Example Ruby :

for tlist in object.tree-lists
…
end

Error would be:

NoMethodError in TreeController#importproject
undefined method `tree’ for #TreeLib::Record:0x39171e8

Thanks in advance.
Paul

2

2006/7/7, Paul H. [email protected]:

Example XML:
Example Ruby :

for tlist in object.tree-lists
…
end

Error would be:

NoMethodError in TreeController#importproject
undefined method `tree’ for #TreeLib::Record:0x39171e8

Either use method send or use another tool to work with XML or use
another way to access objects (if this lib provides one, maybe
object[“tee-list”] or object[:tree-list]).

Kind regards

robert

3

On 7/7/06, Paul H. [email protected] wrote:

…

…

Example Ruby :

for tlist in object.tree-lists
…
end

I’m not certain how xmlsimple works, but I assume it’s dynamically
generating methods (or using method_missing) to map methods as
pseudo-properties onto the XML elements. If so, this might work:

for tlist in object.send(:‘tree-lists’)
…
end

Ruby doesn’t like you having methods with hyphens in the name
syntactically, but semantically, there’s nothing wrong with it. You
can create methods with hyphenated names using define_method, just not
def. And you can call methods with hyphenated names using send, just
not the standard dot syntax. It is of course discouraged, being highly
ugly, but it is possible. :slight_smile:

Jacob F.

4

On 7/7/06, Robert K. [email protected] wrote:

Either use method send or use another tool to work with XML or use
another way to access objects (if this lib provides one, maybe
object[“tee-list”] or object[:tree-list]).

I agree with Robert that if the lib provides hash-style access, that’s
probably a cleaner way to go. Note, though, that if the hash needs a
symbol rather than a string, it will need to use quotes also, as I did
in my other post:

object[:‘tree-list’]

Omitting the quotes would give a syntax error:

$ irb

hash = {}
=> {}
hash[:tree-list]
NameError: undefined local variable or method `list’ for main:Object

Jacob F.

5

Robert K. wrote:

2006/7/7, Paul H. [email protected]:

Example XML:
Example Ruby :

for tlist in object.tree-lists
…
end

Error would be:

NoMethodError in TreeController#importproject
undefined method `tree’ for #TreeLib::Record:0x39171e8

Either use method send or use another tool to work with XML

Are you referring to something like:
object.send(‘tree-list’)

I did a quick search, but have not tried it yet.

or use
another way to access objects (if this lib provides one, maybe
object[“tee-list”] or object[:tree-list]).

The tree-lists and tree-list are both hashes, but for some reason I
still get exceptions. I will keep playing with it. Surely I am not the
only one that has run into this problem.

Thanks for your help!

Kind regards

robert

6

2006/7/7, Paul H. [email protected]:

Omitting the quotes would give a syntax error:

$ irb

hash = {}
=> {}
hash[:tree-list]
NameError: undefined local variable or method `list’ for main:Object

That is the error that I saw all too often.

Yeah, that’s caused by Ruby parsing “:foo” “-” “bar”. Sorry, I should
have used the proper syntax, Jacob is right of course, you need
:“foo-bar” or :‘foo-bar’. So the list of options now looks like this

object.send “foo-bar”
object.send :“foo-bar”
object[“foo-bar”]
object[:“foo-bar”]

Plus same methods with double quotes replaced by single quotes.

robert

7

Jacob F. wrote:

On 7/7/06, Robert K. [email protected] wrote:

Either use method send or use another tool to work with XML or use
another way to access objects (if this lib provides one, maybe
object[“tee-list”] or object[:tree-list]).

I agree with Robert that if the lib provides hash-style access, that’s
probably a cleaner way to go. Note, though, that if the hash needs a
symbol rather than a string, it will need to use quotes also, as I did
in my other post:

object[:‘tree-list’]

Now that makes sense. I never tried it like this. Wow, what an insight.
:slight_smile:

Omitting the quotes would give a syntax error:

$ irb

hash = {}
=> {}
hash[:tree-list]
NameError: undefined local variable or method `list’ for main:Object

That is the error that I saw all too often.

Jacob F.

8

You guys are great. Thanks so much!