Class name as a variable

[Im still]

[Note: parts of this message were removed to make it a legal post.]

Hi all

I'm thinking about a question, that is : Several classes will have a method
in a same name (probably do same thing too).
then in a program I want the method calling class name coming from a
variable( or maybe a result of a expr).

for example:

class A
def abc end
end

class B
def abc end
end

#what i want to do is something like

a = a_variable.abc # a_variable = A | B

Now I'm doing this by

a = eval(" #{a_variable}.abc ")

My question is, is there any better (or nicer) way to doing this?

Thanks

 

[spox]

Hi all

I'm thinking about a question, that is : Several classes will have a method
in a same name (probably do same thing too).
then in a program I want the method calling class name coming from a
variable( or maybe a result of a expr).

for example:

class A
def abc end
end

class B
def abc end
end

#what i want to do is something like

a = a_variable.abc # a_variable = A | B

Now I'm doing this by

a = eval(" #{a_variable}.abc ")

My question is, is there any better (or nicer) way to doing this?

Thanks

With how you asked your question, I'm assuming you want to call a static
method. Otherwise, what's the point of the eval. So, is something like this
what you are after:

class A
def A.abc
"fu"
end
end
class B
def B.abc
"bar"
end
end

With this, there are a couple ways to do this. One, have your variable hold
the constant:

var = A
var.abc -> "fu"
var = B
var.abc -> "bar"

If the variable holds the class name as a string, or symbol, you can fetch the
constant:

var = 'A'
Kernel.const_get(var).abc -> "fu"
var = :B
Kernel.const_get(var).abc -> "bar"

 

[Bertram Scharpf]

Hi,

Am Donnerstag, 20. Aug 2009, 04:07:06 +0900 schrieb Im still:

a = eval(" #{a_variable}.abc ")

My question is, is there any better (or nicer) way to doing this?

[untested]

What you are doing is

a = eval a_variable.to_s.abc.to_s

You probably meant

a = eval a_variable.abc.to_s

or even something else.

Bertram

 

[Im still]

[Note: parts of this message were removed to make it a legal post.]

With how you asked your question, I'm assuming you want to call a static
method. Otherwise, what's the point of the eval. So, is something like this
what you are after:

class A
def A.abc
"fu"
end
end
class B
def B.abc
"bar"
end
end

With this, there are a couple ways to do this. One, have your variable hold
the constant:

var = A
var.abc -> "fu"
var = B
var.abc -> "bar"

If the variable holds the class name as a string, or symbol, you can fetch
the
constant:

var = 'A'
Kernel.const_get(var).abc -> "fu"
var = :B
Kernel.const_get(var).abc -> "bar"


==============

Hi Spox
Ye, they should be static methods, else it will be wrong. My mistake Thanks
very much, what you told is exactly what I want !

 

[Im still]

[Note: parts of this message were removed to make it a legal post.]

Hi,

Am Donnerstag, 20. Aug 2009, 04:07:06 +0900 schrieb Im still:

a = eval(" #{a_variable}.abc ")

My question is, is there any better (or nicer) way to doing this?

[untested]

What you are doing is

a = eval a_variable.to_s.abc.to_s

You probably meant

a = eval a_variable.abc.to_s

or even something else.

Bertram


--
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de

=======================

Hi Bertram Scharpf
I think you didn't get me well.
But thank you for the same for replying