This form
```
contents = open(fn, "r") do io
do_sth(io)
end
```
returns the result of `do_sth`; the close is implicit.
Otherwise, you'll have to introduce a local variable, as in
```
try
io = open(fn)
res = do_sth(io)
close(io)
res
end
-erik
On Sun, Dec 6, 2015 at 9:30 PM, Seth <catch...@bromberger.com> wrote:
> This gets more complicated because the return value from the try and catch
> blocks will be the close() statement, when I really want the output from
> do_sth. How do you work around that?
>
> On Sunday, December 6, 2015 at 6:02:21 PM UTC-8, Erik Schnetter wrote:
>>
>> I would separate the two independent access methods:
>> ```
>> try
>> io = zlibopen
>> do_sth(io)
>> close(io)
>> catch
>> io = open
>> do_sth(io)
>> close(io)
>> end
>> ```
>>
>> If you want another try block to ensure the file is closed, I'd open
>> secondary try blocks within this one. I think you're trying to do two
>> things at once -- see whether zlib is needed, and also check for I/O errors.
>>
>> Incidentally, you don't need a `finally` clause for the regular `open`
>> function; you can instead write
>>
>> ```
>> contents = open(fn, "r") do io
>> do_sth(io)
>> end
>> ```
>>
>> which ensures that `io` will be closed no matter what.
>>
>> -erik
>>
>>
>> On Sun, Dec 6, 2015 at 8:16 PM, Seth <catc...@bromberger.com> wrote:
>>
>>> Hi,
>>>
>>> I'm moving from Gzip.jl to Libz.jl, and am running into a problem. Gzip
>>> used to allow a file to be opened using its methods even if the file was
>>> not encrypted. Libz doesn't allow that.
>>>
>>> The problem I'm having is that I can't figure out a try/catch/finally
>>> that works. Basically, I want this (pseudocode):
>>>
>>> io = ZlibInflateInputStream(open(fn,"r")) # this will succeed if fn
>>> exists, even if fn isn't compressed
>>> contents = try
>>> do_something_with_io(io) # this will error if fn isn't compressed
>>> catch
>>> io = open(fn,"r") # so we try to open it as an uncompressed file
>>> do_something_with_io(io)
>>> finally
>>> close(io)
>>> end
>>>
>>> but this doesn't work (the finally statement fails, for one).
>>>
>>> What's the accepted way of doing this?
>>>
>>
>>
>>
>> --
>> Erik Schnetter <schn...@gmail.com>
>> http://www.perimeterinstitute.ca/personal/eschnetter/
>>
>
--
Erik Schnetter <schnet...@gmail.com>
http://www.perimeterinstitute.ca/personal/eschnetter/
