Hi,
I’d greatly appreciate feedback on the following code.
def create_files
names_array = self.read_names #another method in my class
while names_array.length != 0
name = names_array.pop
File.open( name, "w" ) { |f| f.puts "File is no longer empty" }
end
x.create_files
Which results in:
C:/Scripts/Ruby/file_gen.rb:34:in initialize': Invalid argument - echo (Errno ::EINVAL) from C:/Scripts/Ruby/file_gen.rb:34:inopen’
from C:/Scripts/Ruby/file_gen.rb:34:in `create_files’
from C:/Scripts/Ruby/file_gen.rb:42
The array contains the strings ‘alpha’ through ‘foxtrot’ and before
producing the error above the file ‘foxtrot’ is created. So the logic
works once before failing.
When I pull this code out of the class definition it works perfectly
and creates
a file for every name in the array. What noob mistakes am I making?
Thanks,
S.
On Friday 20 June 2008, [email protected] wrote:
name = names_array.pop
When I pull this code out of the class definition it works perfectly
and creates
a file for every name in the array. What noob mistakes am I making?
Thanks,
S.
To understand what’s going on, one should understand what the error
Errno::EINVAL means. Unfortunately, the only explaination a very quick
search
returned is this:
“Invalid argument. This is used to indicate various kinds of problems
with
passing the wrong argument to a library function.”
I don’t know what can be causing it. I tried passing non-string
arguments to
File.open, but I always got TypeError s, except when I tried passing an
integer, which gave me an Errno::EBADF exception (I’m on linux, though,
so
maybe on windows that can give you another kind of error). At any rate,
the
first thing I’d try (maybe you’ve already done it) is to check that
indeed the
contents of names_array is what you think it is, putting a
p names_array
just after creating it.
If that doesn’t give you a clue, you can rewrite the code in a more
rubysh
way. If I understand correctly, you’re simply iterating on all the
elements of
the array and the while loop and calls to pop are simply there to know
when to
stop the loop. In this case, the whole while loop can be replaced by
this:
array_names.each do |n|
File.open(n, “w”){|f| f.puts “File is no longer empty”}
end
The substance of the code shouldn’t change (well, aside from the fact
that the
array won’t be empty at the end), but this should ensure there is no
mistake
in the logic of the loop (I can’t see any, but you never know).
Other than this, I don’t know what else to suggest.
I hope this helps
Stefano
Hi Stefano,
Quoting Stefano C. [email protected]:
while names_array.length != 0
(Errno
Errno::EINVAL means. Unfortunately, the only explaination a very quick search
returned is this:
“Invalid argument. This is used to indicate various kinds of problems with
passing the wrong argument to a library function.”
Firstly, thank you very much for the feedback. I did also look for
more info on Ruby errors. Not much luck finding details on
Errno::EINVAL.
I don’t know what can be causing it. I tried passing non-string arguments to
File.open, but I always got TypeError s, except when I tried passing an
integer, which gave me an Errno::EBADF exception (I’m on linux, though, so
maybe on windows that can give you another kind of error). At any rate, the
first thing I’d try (maybe you’ve already done it) is to check that
indeed the contents of names_array is what you think it is, putting a
p names_array just after creating it.
I did replace ‘File.open( name, “w” ) { |f| f.puts “File is no longer
empty” }’ with ‘puts name’ and ‘puts name.class’ just to make sure.
Sure enough all the array elements are neatly popped out and they are
strings.
If that doesn’t give you a clue, you can rewrite the code in a more rubysh
way. If I understand correctly, you’re simply iterating on all the
elements of the array and the while loop and calls to pop are simply
there > to know when to stop the loop. In this case, the whole
while loop can be > replaced by this:
Your analysis of the code is correct.
array_names.each do |n|
File.open(n, “w”){|f| f.puts “File is no longer empty”}
end
I’ll try this.
The substance of the code shouldn’t change (well, aside from the
fact that the array won’t be empty at the end), but this should
ensure > there is no mistake in the logic of the loop (I
can’t see any, but you > never know).
Other than this, I don’t know what else to suggest.
I hope this helps
Thanks again for you time and suggestions.
Stefano
Regards,
S.
unknown wrote:
Just a quick update: a friend ran my entire code on Mac/Unix and it
worked perfectly. The problem appears to be Windows related…ughh.
I’d be highly suspicious of the file names, looking for things like
trailing whitespace etc.
Also I’d try opening each file like this:
f = File.open(name, “w”)
f.puts(“File is no longer empty”)
f.fsync
f.close
The fewer operations you do in one line the better from a debugging
point of view. (The f.sync is to ensure that no buffering occurs, just
in case.)
Hi Stefano,
Just a quick update: a friend ran my entire code on Mac/Unix and it
worked perfectly. The problem appears to be Windows related…ughh.
Thanks,
S.
Quoting Stefano C. [email protected]:
Thanks Dave. I’ll give this a try. I almost choked when my friend told
it ran without changes on OS X.
S.
Quoting Dave B. [email protected]: