Question about exiting from a block

Ruby
1

def test
puts ‘before’
yield 2
puts ‘after’
end

test do |i|
XXX if i > 1

a lot of code appears below

end

I have code above and wonder if it is possible to use
return/break/anything to stop execution of block and return control to
test() to execute code after yield. I know it is impossible in 1.8. How
about 1.9? Does anyone feel this is an important feature to have?

Thank you.
Guoliang C.

2

Guoliang C. wrote:

I have code above and wonder if it is possible to use
return/break/anything to stop execution of block and return control to
test() to execute code after yield. I know it is impossible in 1.8. How
about 1.9? Does anyone feel this is an important feature to have?

It is possible in 1.8, using the next keyword:

def test
puts ‘before’
yield 2
puts ‘after’
end

test do |i|
next if i > 1
puts “a lot of code”
end

3

Guoliang C. [email protected] wrote:

I have code above and wonder if it is possible to use
return/break/anything to stop execution of block and return control to
test() to execute code after yield. I know it is impossible in 1.8.

Why is it impossible? Doesn’t “break” do what you need? (And remember,
“break” and “next” can even return a value from a block to the yielder.)
m.

4

matt neuburg wrote:

a lot of code appears below

end

I have code above and wonder if it is possible to use
return/break/anything to stop execution of block and return control to
test() to execute code after yield. I know it is impossible in 1.8.

Why is it impossible? Doesn’t “break” do what you need? (And remember,
“break” and “next” can even return a value from a block to the yielder.)

Nope, break will skip the “after” line.

5

Joel VanderWerf wrote:

Guoliang C. wrote:

I have code above and wonder if it is possible to use
return/break/anything to stop execution of block and return control to
test() to execute code after yield. I know it is impossible in 1.8. How
about 1.9? Does anyone feel this is an important feature to have?

It is possible in 1.8, using the next keyword:

def test
puts ‘before’
yield 2
puts ‘after’
end

test do |i|
next if i > 1
puts “a lot of code”
end

This is great! I never thought of using ‘next’.

Thank you!

6

Keeping it simple:

def test
puts ‘before’
yield 2
puts ‘after’
end

test do |i|
unless i > 1
puts “a lot of code here”
end
end

There’s also throw/catch:

test do |i|
catch(:done) do
throw(:done) if i > 1
puts “a lot of code here”
end
end

7

Hi,

Am Freitag, 05. Jun 2009, 06:48:43 +0900 schrieb Joel VanderWerf:

Guoliang C. wrote:

I have code above and wonder if it is possible to use
return/break/anything to stop execution of block and return control to
test() to execute code after yield. I know it is impossible in 1.8. How
about 1.9?

It is possible in 1.8, using the next keyword:

Slightly modified:

def f ; puts “A” ; puts yield ; puts “Z” ; “F” ; end

f { next “X” ; puts “Y” } #=> “F”
puts “-”
f { break “X” ; puts “Y” } #=> “X”

The output is:

A
X
Z

A

Will this work in 1.9, too?

Bertram

8

Joel VanderWerf [email protected] wrote:

XXX if i > 1

Nope, break will skip the “after” line.

Right, sorry about that. m.