Non-Hard Coded File.open(newFile)

Ruby
1

Like a lot of people I’m new to Ruby and I’m trying to do something I
thought would be pretty simple. I want the user to give me input in the
form of a filename and then subsequently open the file. Here is what I
have so far:

class FileHandler

def initialize()
@fileToParse = fileToParse #I get user input in the form of gets in
#another class.
if File.new(fileToParse)
puts ‘File successfully opened.’
else
puts ‘File failed to open.’
Kernel.exit

end

end
end

However, that won’t work. Doing something like
File.new(“C:/Users/grant/Desktop/test.txt”) works just fine though. The
way I’m currently doing it throws the following error:

F:/Programming/eclipseWorkspace/CSE_655/file_handler.rb:8:in
`initialize’: Invalid argument - C:/Users/grant/Desktop/test.txt
(Errno::EINVAL)

2

On Sat, Oct 23, 2010 at 6:35 AM, Grant C. [email protected]
wrote:

Like a lot of people I’m new to Ruby and I’m trying to do something I
thought would be pretty simple. I want the user to give me input in the
form of a filename and then subsequently open the file. Here is what I
have so far:

def initialize()
@fileToParse = fileToParse #I get user input in the form of gets in
#another class.

Are you removing the newline at the end of the string from gets ?

F:/Programming/eclipseWorkspace/CSE_655/file_handler.rb:8:in
`initialize’: Invalid argument - C:/Users/grant/Desktop/test.txt

Probably actually “C:/Users/grant/Desktop/test.txt\n” right here ^

(Errno::EINVAL)

HTH,

3

On Saturday 23 October 2010, Grant C. wrote:

| if File.new(fileToParse)
|File.new(“C:/Users/grant/Desktop/test.txt”) works just fine though. The
|way I’m currently doing it throws the following error:
|
|F:/Programming/eclipseWorkspace/CSE_655/file_handler.rb:8:in
|`initialize’: Invalid argument - C:/Users/grant/Desktop/test.txt
|(Errno::EINVAL)

Your code seems mostly correct, but I don’t exactly understand what
fileToParse is. Is it a call to a fileToParse method (which in turn uses
geets
to retrieve the file name) or a variable? In the first case, I guess the
if
line should be

if File.new(@fileToParse) #note the @

Otherwise, the user will be asked to enter the file name twice.

If fileToParse is a variable, instead, where does it come from?

Also, it would be useful if you pointed out which is line 8 on your
program.
If I assume the first line is

class FileHandler

then line 8 is ‘else’, which I doubt could give you such an error.

Stefano

4

Thank you so much Hassan, that fix seemed so obvious after you said it
lol. I just changed line 8 to if File.new(fileToParse.delete “\n”) and
it worked just fine. Not sure if I should ask this here but just out of
curiosity does the debugger for 1.9.2 not work? I’m running the eclipse
plug in right now and whenever I try to debug it just vomits all over
itself. Browsed around the web and saw it mentioned a couple of times.

5

On Sat, Oct 23, 2010 at 8:17 AM, Grant C. [email protected]
wrote:

Thank you so much Hassan, that fix seemed so obvious after you said it
lol. I just changed line 8 to if File.new(fileToParse.delete “\n”)

Good, but you should probably look at fileToParse.chomp for a more
platform-agnostic approach :slight_smile:

Not sure if I should ask this here but just out of
curiosity does the debugger for 1.9.2 not work? I’m running the eclipse
plug in right now

Sorry, no idea about Eclipse.

6

On Oct 23, 8:35am, Grant C. [email protected] wrote:

Like a lot of people I’m new to Ruby and I’m trying to do something I
thought would be pretty simple. I want the user to give me input in the
form of a filename and then subsequently open the file. Here is what I
have so far:

class FileHandler

def initialize()
@fileToParse = fileToParse #I get user input in the form of gets in

Usually after gets you want to use strip to remove all leading
and trailing whitespace:

file_name = gets.strip