Problem with 2nd File.Read in small script

Guest16 · 9 May 2006 13:00

Hello,
Can someone look at my code below? I have a RUBY debugger that indicates
to me that when I get to the 2nd "File.read" below, all of the previous
variables are wiped away. I'd like to know why that is. I need to do 2
searches, 2 scans, in the same files. It doesn't seem to like my 2nd
pass. As a result, nothing past my 2nd File.read occurs.

Thank you.

···

--------------------------------------------------------------------------------
require 'FileUtils'
Dir.chdir("c:/scripts/ruby/temp")
psfiles = Dir.glob('*.ps')

blankpages = []

psfiles.each do |psfile|
infofile = File.basename(psfile, '.ps')
  File.open(psfile, "a") do |writepage|
    File.read(psfile).scan(/\%\%Pages: (\d{1,5})\n/) do
     totalnumberofpages = $1
     #If the page count is odd, then, add a blank to make it an even
page count.
     if (totalnumberofpages.to_i % 2) !=0 then
       writepage << "\%\%Blank page from Asura\nshowpage\n"
       blankpages = totalnumberofpages.to_i + 1.to_i
     end
    end

  File.read(psfile).scan(/\%\%Page: [(\d)()]+
(\d{1,5})\n\%\%PageBoundingBox:
  \d{1,5} \d{1,5} \d{1,5} \d{1,5}\n\%\%PageOrientation:/) do
    blankpages.push($1)
    File.open(infofile + ".pageinfo", "w") do |writetext|
      writetext << "Number of blankpages in this PDF:
#{blankpages.length}\n" <<
      "Blank Pages in This PDF: #{blankpages.join(' ')}\n"
    end
  end
  end
end

--
Posted via http://www.ruby-forum.com/.

Collins_Justin · 9 May 2006 18:05

Peter Bailey wrote:

Hello,
Can someone look at my code below? I have a RUBY debugger that indicates to me that when I get to the 2nd "File.read" below, all of the previous variables are wiped away. I'd like to know why that is. I need to do 2 searches, 2 scans, in the same files. It doesn't seem to like my 2nd pass. As a result, nothing past my 2nd File.read occurs.

Thank you.

--------------------------------------------------------------------------------
require 'FileUtils'
Dir.chdir("c:/scripts/ruby/temp")
psfiles = Dir.glob('*.ps')

blankpages =

psfiles.each do |psfile|
infofile = File.basename(psfile, '.ps')
  File.open(psfile, "a") do |writepage|
    File.read(psfile).scan(/\%\%Pages: (\d{1,5})\n/) do
     totalnumberofpages = $1
     #If the page count is odd, then, add a blank to make it an even page count.
     if (totalnumberofpages.to_i % 2) !=0 then
       writepage << "\%\%Blank page from Asura\nshowpage\n"
       blankpages = totalnumberofpages.to_i + 1.to_i
     end
    end

  File.read(psfile).scan(/\%\%Page: [(\d)()]+ (\d{1,5})\n\%\%PageBoundingBox:
  \d{1,5} \d{1,5} \d{1,5} \d{1,5}\n\%\%PageOrientation:/) do
    blankpages.push($1)
    File.open(infofile + ".pageinfo", "w") do |writetext|
      writetext << "Number of blankpages in this PDF: #{blankpages.length}\n" <<
      "Blank Pages in This PDF: #{blankpages.join(' ')}\n"
    end
  end
end

I think part of the issue here is that you open the file for writing, then do a read on the same file. Looking at IO.read:

Opens the file, optionally seeks to the given offset, then returns /length/ bytes (defaulting to the rest of the file). read ensures the file is closed before returning.

But you have already opened the file. So, your structure above looks something like:

File.open(psfile) { #opens psfile

File.read(psfile) { #opens psfile

} #closes psfile

File.read(psfile) { #opens psfile

} #closes psfile

I'm not sure if that is the problem or not.

-Justin

Guest16 · 9 May 2006 18:58

Justin Collins wrote:

Peter Bailey wrote:

require 'FileUtils'
     #If the page count is odd, then, add a blank to make it an even
    blankpages.push($1)
    File.open(infofile + ".pageinfo", "w") do |writetext|
      writetext << "Number of blankpages in this PDF:
#{blankpages.length}\n" <<
      "Blank Pages in This PDF: #{blankpages.join(' ')}\n"
    end
  end
  end
end

I think part of the issue here is that you open the file for writing,
then do a read on the same file. Looking at IO.read:

Opens the file, optionally seeks to the given offset, then returns
/length/ bytes (defaulting to the rest of the file). read ensures the
file is closed before returning.

But you have already opened the file. So, your structure above looks
something like:

File.open(psfile) { #opens psfile

    File.read(psfile) { #opens psfile

    } #closes psfile

    File.read(psfile) { #opens psfile

    } #closes psfile

} #closes psfile

I'm not sure if that is the problem or not.

-Justin

Thanks, Justin. Your comments made me dive deeper, and, it works!
Obviously, there shouldn't be any reason why I couldn't read a file
twice, or as many times as I needed. But, I did make it neater here,
closing one read before starting another. . . .

require 'FileUtils'
Dir.chdir("c:/scripts/ruby/temp")
psfiles = Dir.glob('*.ps')

blankpages =
totalpages = 0

psfiles.each do |psfile|
infofile = File.basename(psfile, '.ps')
#Scan for the number of pages in the original PDF.
File.read(psfile).scan(/\%\%Pages: (\d{1,5})\n/) do
  File.open(psfile, "a") do |writepage|
   totalpages = $1
   #totalpages.push($1)
   #If the page count is odd, then, add a blank to make it an even page
count.
   if (totalpages.to_i % 2) !=0 then
    writepage << "\%\%Blank page from Asura\nshowpage\n"
    totalpages = totalpages.to_i + 1.to_i
   end
end
end
File.read(psfile).scan(/\%\%Page: [(\d)()]+
(\d{1,5})\n\%\%PageBoundingBox:
  \d{1,5} \d{1,5} \d{1,5} \d{1,5}\n\%\%PageOrientation:/) do
  blankpages = $1
  end
   File.open(infofile + ".pageinfo", "w") do |writetext|
    writetext << "Total number of pages in this PDF: #{totalpages}\n"
<<\
    "Number of blank pages in this PDF: \
#{blankpages.length}\n" << "Blank Pages\ in This PDF:
#{blankpages.join(' ')}\n"
      end
end

···

--
Posted via http://www.ruby-forum.com/\.

Logan_Capaldo · 9 May 2006 19:09

If you are going to File.read the whole file into memory anyway, I would do it once, make _all_ my modifications on the string and then write the whole string out.

e.g.

file_contents = File.read(psfile)

file_contents.scan(\%\%Pages: (\d{1,5})\n/) do
     if odd
       file_contents << blank_page
     end
end

file_contents.scan(/\%\%Page: [(\d)()]+
(\d{1,5})\n\%\%PageBoundingBox:
\d{1,5} \d{1,5} \d{1,5} \d{1,5}\n\%\%PageOrientation:/) do
...
end

File.open(psfile, "w") { |f| f.print file_contents }

···

On May 9, 2006, at 2:58 PM, Peter Bailey wrote:

Justin Collins wrote:

Peter Bailey wrote:

require 'FileUtils'
     #If the page count is odd, then, add a blank to make it an even
    blankpages.push($1)
    File.open(infofile + ".pageinfo", "w") do |writetext|
      writetext << "Number of blankpages in this PDF:
#{blankpages.length}\n" <<
      "Blank Pages in This PDF: #{blankpages.join(' ')}\n"
    end
  end
end

I think part of the issue here is that you open the file for writing,
then do a read on the same file. Looking at IO.read:

Opens the file, optionally seeks to the given offset, then returns
/length/ bytes (defaulting to the rest of the file). read ensures the
file is closed before returning.

But you have already opened the file. So, your structure above looks
something like:

File.open(psfile) { #opens psfile

    File.read(psfile) { #opens psfile

    } #closes psfile

    File.read(psfile) { #opens psfile

    } #closes psfile

} #closes psfile

I'm not sure if that is the problem or not.

-Justin

Thanks, Justin. Your comments made me dive deeper, and, it works!
Obviously, there shouldn't be any reason why I couldn't read a file
twice, or as many times as I needed. But, I did make it neater here,
closing one read before starting another. . . .

require 'FileUtils'
Dir.chdir("c:/scripts/ruby/temp")
psfiles = Dir.glob('*.ps')

blankpages =
totalpages = 0

psfiles.each do |psfile|
infofile = File.basename(psfile, '.ps')
#Scan for the number of pages in the original PDF.
File.read(psfile).scan(/\%\%Pages: (\d{1,5})\n/) do
  File.open(psfile, "a") do |writepage|
   totalpages = $1
   #totalpages.push($1)
   #If the page count is odd, then, add a blank to make it an even page
count.
   if (totalpages.to_i % 2) !=0 then
    writepage << "\%\%Blank page from Asura\nshowpage\n"
    totalpages = totalpages.to_i + 1.to_i
   end
end
File.read(psfile).scan(/\%\%Page: [(\d)()]+
(\d{1,5})\n\%\%PageBoundingBox:
  \d{1,5} \d{1,5} \d{1,5} \d{1,5}\n\%\%PageOrientation:/) do
  blankpages = $1
  end
   File.open(infofile + ".pageinfo", "w") do |writetext|
    writetext << "Total number of pages in this PDF: #{totalpages}\n"
<<\
    "Number of blank pages in this PDF: \
#{blankpages.length}\n" << "Blank Pages\ in This PDF:
#{blankpages.join(' ')}\n"
      end
end

--
Posted via http://www.ruby-forum.com/\.

Guest16 · 9 May 2006 19:49

Logan Capaldo wrote:

···

On May 9, 2006, at 2:58 PM, Peter Bailey wrote:

  end

file is closed before returning.

blankpages =
page
  blankpages = $1

--
Posted via http://www.ruby-forum.com/\.

If you are going to File.read the whole file into memory anyway, I
would do it once, make _all_ my modifications on the string and then
write the whole string out.

e.g.

file_contents = File.read(psfile)

file_contents.scan(\%\%Pages: (\d{1,5})\n/) do
     if odd
       file_contents << blank_page
     end
end

file_contents.scan(/\%\%Page: [(\d)()]+
(\d{1,5})\n\%\%PageBoundingBox:
   \d{1,5} \d{1,5} \d{1,5} \d{1,5}\n\%\%PageOrientation:/) do
...
end

File.open(psfile, "w") { |f| f.print file_contents }

Good idea! Thanks, Logan. I'll try it. I've got a pretty healthy box,
with lots of memory, so, I may as well just do it all in there at once.
You're right.

-Peter

--
Posted via http://www.ruby-forum.com/\.

Robert_K1 · 10 May 2006 12:59

If you cannot do that I guess it's still more efficient to open the
file *once* for reading and writing instead of opening and closing it
all the time and then do all the operations before closing it again.

14:53:21 [tmp]: echo 1 > x
14:53:24 [tmp]: ruby -e 'File.open("x", File::RDWR) {|io| io.seek 0;
puts io.read; io.seek 0, IO::SEEK_END; io.puts "foo"}'
1
14:54:51 [tmp]: cat x
1
foo

HTH

robert

···

2006/5/9, Peter Bailey <pbailey@bna.com>:

Logan Capaldo wrote:

> If you are going to File.read the whole file into memory anyway, I
> would do it once, make _all_ my modifications on the string and then
> write the whole string out.

Good idea! Thanks, Logan. I'll try it. I've got a pretty healthy box,
with lots of memory, so, I may as well just do it all in there at once.
You're right.

--
Have a look: Robert K. | Flickr

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