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


#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 removed_email_address@domain.invalid 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

http://www.ruby-doc.org/core/classes/Proc.html#M001573

Regards,
Pit


#5

2008/11/26 Jan F. removed_email_address@domain.invalid

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
removed_email_address@domain.invalid 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