Verify if a class exists


#1

Hello everybody,

is there a way to check, if a class exists? I create classes dynamically
and would like to know before, if a class with that name already exists.

Thanks for your help
Bernd


#2

On 7/4/07, Bernd removed_email_address@domain.invalid wrote:

Try a const_get. Like so:

def class_exists?(name)
begin
true if Kernel.const_get(name)
rescue NameError
false
end
end


#3

Simen E. wrote:

On 7/4/07, Bernd removed_email_address@domain.invalid wrote:

Try a const_get. Like so:

def class_exists?(name)
begin
true if Kernel.const_get(name)
rescue NameError
false
end
end

Hi,
first of all, thanks for your help, Simen. I think, I even found a
better solution, I assign the name to the class with

Object.const_set class_name, klass

So I can determine, whether the class exists with

Object const_defined? class_name

You are using exception handling (rescue) for a conditional branch,
which I try to avoid whenever possible, to keep my code well structured.


#4

On 7/4/07, Bernd B. removed_email_address@domain.invalid wrote:

rescue NameError
So I can determine, whether the class exists with

Object const_defined? class_name

You are using exception handling (rescue) for a conditional branch,
which I try to avoid whenever possible, to keep my code well structured.

There is a const_defined? method? Ah, I see it’s been some time since
I programmed Ruby. Excuse my ignorant advice, it seems you find a
better solution :slight_smile: