instance_variable_[gs]et

[Trans]

Just spinning wheels this evening...

Why does #instance_variable_get/set require an "@" sign in front of
the variable name? It's not like there is any other valid instance
variable name, is there?

And why can't #instance_variable_set take a hash to set more than one
variable at a time?

T.

 

[Florian Gilcher]

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And why can't #instance_variable_set take a hash to set more than one
variable at a time?

T.

By the way, if you really need it, it is easily implemented on your own:
Example:

def set_instance_variables(variables)
variables.each do |key, value|
instance_variable_set("@#{key}", value)
end
end

Greetings
Florian
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[Trans]

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Hash: SHA1




By the way, if you really need it, it is easily implemented on your own:
Example:

def set_instance_variables(variables)
variables.each do |key, value|
instance_variable_set("@#{key}", value)
end
end

Yes, of course. Facets has #instance_assign, but it just seems
wasteful when one method could do.

I don't quite get matz take. How is

variables.each do |key, value|
instance_variable_set("@#{key}", value)
end

cleaner than

instance_variable_set(variables)

T.

 

[Robert Klemme]

Yes, of course. Facets has #instance_assign, but it just seems
wasteful when one method could do.

I don't quite get matz take. How is

variables.each do |key, value|
instance_variable_set("@#{key}", value)
end

cleaner than

instance_variable_set(variables)

How often is that really needed? I can remember only few cases where I
needed that - and those were probably more experimental.

Kind regards

robert

 

[Joel VanderWerf]

On 27.03.2008 16:28, Trans wrote: ...

How often is that really needed? I can remember only few cases where I
needed that - and those were probably more experimental.

I've got a couple of methods in library code I use frequently that
initialize or populate an object from a hash using the loop above. I've
always thought it was kind of a pain (and inefficient) to have to
construct a string for each key.

Why couldn't #instance_variable_set be agnostic about whether you refer
to ivars as "foo" or "@foo" ? I don't see any ambiguity...

 

[Rados³aw Bu³at]

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[Joel VanderWerf]

Does it mean that everyone use/need it? I don't think so.

Don't see what that has to do with anything. There's lots of core
methods that are rarely used. Have you used
Modulerotected_method_defined? recently?

I don't know if it's main reason but AFAIR Ruby internally use
instance variables without "@" character to store additional
information about object (but from Ruby you can't get it).

That's a good point, but my suggestion was for #instance_variable_set to
map both "foo" and "@foo" to the same entry in the table, namely the
entry for "@foo". Hidden entries would remain hidden.

I think that most important is consistent. We use @ in code and the
same goes when we want get value by instance_variable_get method.

Maybe.

 

[Eric Hodel]

Just spinning wheels this evening...

Why does #instance_variable_get/set require an "@" sign in front of
the variable name? It's not like there is any other valid instance
variable name, is there?

There are, but you can only get to them from C.