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comp.lang.ruby

FasterCSV - Writing to File Question

Drew Olson

12/13/2006 10:03:00 PM

Based on a previous thread, I gave FasterCSV a try and I've been very
impressed with the performance increases. However, something about the
syntax for writing to a file bothers me. Is there any way to create a
"writer object" to write to a file? For example, this is how I'm
currently using FasterCSV:

FCSV.open(my_file,"w") do |out|
out << my_data
...
end

What I'd like to do is something along the lines of:

out = FCSV.open(my_file,"w")
out << my_data
...
out.close

Is this functionality present? If not, is this a design decision? I
guess it just bothers me to have to wrap a block around all my code that
has to do with writing to a file.

Thanks in advance,
Drew

--
Posted via http://www.ruby-....
4 Answers

Drew Olson

12/13/2006 10:15:00 PM

0

Drew Olson wrote:
snip
> Thanks in advance,
> Drew

Well, irb is my friend and I should have used it before asking.
FasterCSV indeed does have this functionality and it works as expected.
I had an error with this functionality before posting but it must have
been my mistake.

Thanks,
Drew

--
Posted via http://www.ruby-....

Kenosis

12/13/2006 10:16:00 PM

0


Drew Olson wrote:
> Based on a previous thread, I gave FasterCSV a try and I've been very
> impressed with the performance increases. However, something about the
> syntax for writing to a file bothers me. Is there any way to create a
> "writer object" to write to a file? For example, this is how I'm
> currently using FasterCSV:
>
> FCSV.open(my_file,"w") do |out|
> out << my_data
> ...
> end
>
> What I'd like to do is something along the lines of:
>
> out = FCSV.open(my_file,"w")
> out << my_data
> ..
> out.close
>
> Is this functionality present? If not, is this a design decision? I
> guess it just bothers me to have to wrap a block around all my code that
> has to do with writing to a file.
>
> Thanks in advance,
> Drew
>
> --
> Posted via http://www.ruby-....

I don't use FCSV but I'd be wouldn't be surprised if it didn't have a
close method (although it may - just have a look at the code.) The
pattern of associating a block with the opening/initialization of a
resource such as a file, connection, etc. is one of Ruby's major
strengths and if the designer of the entity being opened has done their
job right, the entity is (usually) closed for you when the block
terminates. This pattern leads to fewer defects such as leaked file
handles and such. So, I suppose at the end of the day this is a matter
of personal taste but I think most Ruby enthusiasts would prefer the
block to the explicit close. And I do believe this is an example of
the "initialization is acquisition" design pattern, if memory serves
me, so its not as if this is some arcane practice, for what ever my 2
cents are worth :)

Ken

James Gray

12/13/2006 10:19:00 PM

0

On Dec 13, 2006, at 4:02 PM, Drew Olson wrote:

> Based on a previous thread, I gave FasterCSV a try and I've been very
> impressed with the performance increases. However, something about the
> syntax for writing to a file bothers me. Is there any way to create a
> "writer object" to write to a file? For example, this is how I'm
> currently using FasterCSV:
>
> FCSV.open(my_file,"w") do |out|
> out << my_data
> ...
> end
>
> What I'd like to do is something along the lines of:
>
> out = FCSV.open(my_file,"w")
> out << my_data
> ...
> out.close
>
> Is this functionality present?

Sure. Should work just fine. (File a bug if it doesn't!)

Just FYI though, the first example is very idiomatic Ruby. We would
always rather let the language clean up after us than to have to
remember to do it ourselves. That's why you see this construct all
over Ruby even with normal File writes.

James Edward Gray II

Drew Olson

12/13/2006 10:23:00 PM

0

James Gray wrote:
> On Dec 13, 2006, at 4:02 PM, Drew Olson wrote:
>
>>
>> What I'd like to do is something along the lines of:
>>
>> out = FCSV.open(my_file,"w")
>> out << my_data
>> ...
>> out.close
>>
>> Is this functionality present?
>
> Sure. Should work just fine. (File a bug if it doesn't!)
>
> Just FYI though, the first example is very idiomatic Ruby. We would
> always rather let the language clean up after us than to have to
> remember to do it ourselves. That's why you see this construct all
> over Ruby even with normal File writes.
>
> James Edward Gray II

James -

Was hoping you'd chime in. Thanks for the explanation, this is what I
expected. I supposed I just have the beat the Java that's remaining in
me by getting used to this type of code. I can certainly see the benefit
of clean up being done for you.

Thanks,
Drew

--
Posted via http://www.ruby-....