From: Oliver Peng <oliver.peng@...>
Date: 2008-03-07T03:28:24+09:00
Subject: Re: the value in ensure block is not returned

Robert Klemme wrote:
> On 06.03.2008 16:46, Oliver Peng wrote:
>> irb(main):009:1> end
>> => nil
>> irb(main):010:0> test
>> => 2
>> 
>> I am expecting that 1 should be returned by is 2.
> 
> Why should it?  If you think about it you will see that it's actually
> good the way it is.  The result of evaluating code in /ensure/ cannot be
> returned under all circumstances (see Gary's reply).  And for normal
> execution of a block of code you want the result of the code block to be
> returned - not the result of /ensure/.  The code in /ensure/ is intended
> to do some cleanup that has to occur under all circumstances but not
> interfere with normal processing.
> 
>> So it is obviously that all codes in ensure block have been run. But the
>> return value is always the last value before ensure block.
> 
> Yes, no problem here.
> 
> Cheers
> 
>   robert

Ok. I see.

I am also curious what will happen if I change the return value in 
ensure block. Here is my test code:

irb(main):003:0> def test
irb(main):004:1> begin
irb(main):005:2* a = 1
irb(main):006:2> b =2
irb(main):007:2> b
irb(main):008:2> ensure
irb(main):009:2* b += 3
irb(main):010:2> end
irb(main):011:1> end
=> nil
irb(main):012:0> test
=> 2

It looks that the result value has been saved to a temp place before 
running ensure block. Is that correct?

I also use global variable to test.

irb(main):014:0> @@value = 0
=> 0
irb(main):015:0> def test1
irb(main):016:1> begin
irb(main):017:2* @@value = 3
irb(main):018:2> ensure
irb(main):019:2* @@value = 8
irb(main):020:2> end
irb(main):021:1> end
=> nil
irb(main):023:0> test1
=> 3
irb(main):024:0> @@value
=> 8

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