Question concerning ruby file access

[Stefan Salewski]

Question concerning ruby file access from a novice:

I have seen following code fragment from

http://www.rubycentral.com/pickaxe/tut_io.html

File.open("testfile", "r") do |aFile|
# ... process the file
end

Advantage of this notation is that file is automatically closed when do
loop terminates -- maybe by an exception with Process.exit.

But how do I test in this notation that the file with name "testfile"
really exits (and opening was successful). In an multi-tasking
environment another process may delete the file just before this
statement is executed.

Or in other words: I want to print a text like "File with filename
"testfile" does not exist" when opening failed.

Best regards

Stefan Salewski

 

[Sebastian Hungerecker]

But how do I test in this notation that the file with name "testfile"
really exits (and opening was successful). In an multi-tasking
environment another process may delete the file just before this
statement is executed.

If you want to completely avoid race conditions, you don't check - you just do
and then recover from eventual errors (i.e. you rescue the exception).

HTH,
Sebastian

 

[Ken Bloom]

Question concerning ruby file access from a novice:

I have seen following code fragment from

http://www.rubycentral.com/pickaxe/tut_io.html

File.open("testfile", "r") do |aFile| # ... process the file
end

Advantage of this notation is that file is automatically closed when do
loop terminates -- maybe by an exception with Process.exit.

But how do I test in this notation that the file with name "testfile"
really exits (and opening was successful). In an multi-tasking
environment another process may delete the file just before this
statement is executed.

Or in other words: I want to print a text like "File with filename
"testfile" does not exist" when opening failed.

Best regards

Stefan Salewski

begin
File.open("testfile") do |aFile|
...
end
rescue IOError => e
#handle error
end

 

[Peña, Botp]

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