How to get a reference to a block (when no explicit block parameter is used?)

Ruby
1

In a function, I can find out if a block was given using block_given?,
but there’s no way I can find to get hold of that block if it’s there–
I can only yield to it, so far as I can tell. I know there has to be a
method somewhere to do this, could some kind soul enlighten me?

Many thanks,
Ken

2

Kenneth McDonald [email protected] wrote:

In a function, I can find out if a block was given using block_given?,
but there’s no way I can find to get hold of that block if it’s there–
I can only yield to it, so far as I can tell. I know there has to be a
method somewhere to do this, could some kind soul enlighten me?

Many thanks,
Ken

def my_meth param, &block
p block
end

Regards,
Jan F.

3

Unfortunately, that produces a method that requires a block–I want
one where the block is optional. But thanks for the feedback.

Ken

4

Ken, you can use Proc.new

class Proc - RDoc Documentation

Regards,
Pit

5

2008/11/26 Jan F. [email protected]

def my_meth param, &block
p block
end

The way I understood the question was as follows:

def my_method(arg)
if block_given?
yield(arg)
end
end

How to get a reference to the given block in this situation? This is
especially true if you use define_method, which cannot specify a block
param
(at least not in 1.8). Any suggestions?

6

Kenneth McDonald wrote:

Unfortunately, that produces a method that requires a block

No, it does not.

HTH,
Sebastian H.

7

On Nov 26, 10:54 am, Kenneth McDonald
[email protected] wrote:

Unfortunately, that produces a method that requires a block–I want
one where the block is optional. But thanks for the feedback.

Did you try it?

my_meth(5) { puts ‘hi’ }
#Proc:0x0006ae28@:10(irb)
my_meth(5)
nil

8

Whoops, apologies to all. Didn’t realize &b arguments were optional.

K