Yet another question on exceptions

ruby-talk
1

File.open is not that stupid ;-). It uses "ensure" internally to close
a file in the case of exception. Using block with open guarantees that
the file will not remain open no matter what.

Gennady.

···

-----Original Message-----
From: Eric Jacoboni [mailto:jaco@neottia.net]
Sent: Friday, February 10, 2006 8:03
To: ruby-talk ML
Subject: Yet another question on exceptions

Hi,

If i use File::open to open/create a file objet, and if i use
a block with it, the file will be automatically close when
the block ends:

Now, considering this buggy snippet:

begin
  File.open("my_file") do |fic|
    fic.puts("bla")
  end
rescue Exception => e
  STDERR.puts(e)
  exit(1)
end

Here, the "not opened for writing" exception will be raised,
the block end will never be reached and the file will remain
opened, isn't it ?
To circumvent this, i have to make fic a global variable and
put the appropriate code in a ensure clause (or open a
begin/ensure in the File.open block to close the file... too bad)

So, my question is: what's the benefit of this idiom versus this one:

begin
fd = File.new("my_file")
     ...
rescue Exception => e
  STDERR.puts(e)
  exit(1)
ensure
fd.close if fd and not fd.closed?
end

Is there something i've missed?
--
Eric Jacoboni, ne il y a 1442972561 secondes