From: Robert Klemme <bob.news@...>
Date: 2004-09-06T02:25:13+09:00
Subject: Re: autochomp?

>>> #---- end filetest.rb -----
>>>
>>> $ seq 10000 > testfile.txt
>>> $ ruby filetest.rb
>>> readlines:  0.050000   0.010000   0.060000 (  0.085483)
>>> inject:  0.130000   0.010000   0.140000 (  0.172144)
>>> foreach:  0.080000   0.000000   0.080000 (  0.112690)
>>
>> That's really interesting.  Did you also test with a real world file (a 
>> file
>> with longer lines presumably)?  Interestingly enough, changing the block 
>> of
>> #inject does make it nearly as fast as readlines:
>
> What's the interesting bit?

The impact of the two statements vs. one statement in the block plus that - 
once again - intuition is proven wrong. :-)

> "readlines" is probably quicker than "inject" since there are less
> method calls.  In "inject" and "foreach" (and "inject2" and "foreach2"
> in your later post), there are two method calls in the block: chomp!
> and <<.  In "readlines" there's only 1.  All that pushing and popping
> of ruby stack frames, method name looking up... it all adds up, more
> so, evidently, than walking the array an extra time.
>
> (Also note that "foreach" won't work right if chomp! returns nil, which
> it will on the last line if there's no newline @ EOF.)

Yes, that was exactly the reason why I first used "line.chomp!; ar << line". 
But I wanted to make it comparable so I added the other variant.

Kind regards

    robert