I have the following software installed
Ruby
1.8.6
Columnize
0.3.6
linecache
0.43
ruby-debug
0.10.4
ruby-debug-base
0.10.4
There is a piece of code that is almost 22,000 lines long. When rdebug moves to this piece of code, it executes it correctly, but does not display the surrounding correct lines of code or the currently executing line.
For example:
foo.a.b("a string")
Is the method. The following is an example of the code
#around line 2000
#e
#j
#h
.
.
.
#around line 6000
def a
return obj_that_b_is_called_on
end
.
.
.
#around line 20000
def b(string)
puts "Hello World"
puts string
string = a
end
The debugger correctly calls on a and displays the information. However, when b is called, the debugger looks at something similar to the code where #e and #j are. The functions inside b execute correctly, print the correct statements, and I can even evaluate the variable string. Is this a buffer or cache issue? Or is this a setting issue that I can configure?
what does a debugger "backtrace" command show?
Is it correct?
What does the value of
eval caller().each {|l| puts l}
show? (If autoeval is "on", you don't need the initial "eval")
Is that correct?
If caller() isn't giving the right information, it's a problem in Ruby 1.8.6. Without going into details, there have been are various weirdnesses in reporting line recording in Ruby. (Actually, I don't remember which versions have some of the problems I know are there.)
Related
# myapp.rb
myvar = 'Hello'
myvar += ' world'
myvar += '!'
puts myvar
puts 'Bye!'
Trying to debug it:
>ruby -rdebug myapp.rb
<...>/ruby-2.7.2-1/lib/ruby/2.7.0/x64-mingw32/continuation.so: warning: callcc is obsolete; use Fiber instead
Debug.rb
Emacs support available.
<...>/ruby-2.7.2-1/lib/ruby/2.7.0/rubygems/core_ext/kernel_require.rb:172: if RUBYGEMS_ACTIVATION_MONITOR.respond_to?(:mon_owned?)
(rdb:1) help
Debugger help v.-0.002b
Commands
b[reak] [file:|class:]<line|method>
b[reak] [class.]<line|method>
set breakpoint to some position
. . .
c[ont] run until program ends or hit breakpoint
. . .
Ok, let's do it:
(rdb:1) b myapp.rb:1
Set breakpoint 1 at D:/temp/r/myapp.rb:1
(rdb:1) cont
Hello world!
Bye!
Actual behavior: doesn't stop at breakpoints.
Expected behavior: must stop at breakpoints.
Used gdb for C/C++ and pdb for Python. They have similar interface and work.
The questions are:
Please tell if you can reproduce this problem.
What is the reason of this problem?
Is this a bug or a feature?
How to make the debugger stop at breakpoints?
Could not google the answer. There's an example here (in the end of the page) that, to my mind, doesn't expressly show the expected breakpoint behavior. As the author didn't demonstrate this simple and obvious use case then there must be a problem here.
UPDATE
Checked in Linux -- works as expected.
Try specifying the absolute filename of the program, in other words try running the program as ruby -rdebug $PWD/myapp.rb
I posted a bug report for version 2.7.2 just now:
https://bugs.ruby-lang.org/issues/17492?next_issue_id=17491
Tried with a previous version of Ruby 2.5.3 -- works as expected. The same is on Linux:
$ ruby -rdebug myapp.rb
/usr/lib/x86_64-linux-gnu/ruby/2.5.0/continuation.so: warning: callcc is obsolete; use Fiber instead
Debug.rb
Emacs support available.
myapp.rb:1:myvar = 'Hello'
(rdb:1) b 3
Set breakpoint 1 at myapp.rb:3
(rdb:1) c
Breakpoint 1, toplevel at myapp.rb:3
myapp.rb:3:myvar += '!'
Probably the problem is in the new version or with my installation in Windows.
I'm having struggles understanding ruby. I wish to have a program in which a user can input a set of text and it come back with asterisks. So far I was able to do it via a .txt file. Can anyone explain where I went wrong? I am struggling with ruby a lot.
Image of outcome when I run it
print "Please enter any length of text:"
user_input = String(gets.chomp)
h = Hash.new
f = user_input
f.each_line { |line|
letters = line.split(//)
letters.each { |w|
if h.has_key?(w)
h[w] = h[w] + 1
else
h[w] = 1
end
}
}
# sort the hash by
h.sort{|a,b| a[1]<=>b[1]}.each { |elem|
puts "\"#{elem[0]}\": " + '*' * elem[1]
}
Error message I encountered
Undefined method `chomp' for nil:NilClass (NoMethodError)
In the script runner of Atom where you are currently running your Ruby program, you can not read from standard input using gets. It appears that the script-runner package can extend this to provide a real terminal to the script where you can then also use STDIN.
Alternatively, you could also run your program from a real console. For that, you have run it from a command line window, e.g. with ruby name_of_program.rb instead of starting it from Atom.
The gets method must be called alone. Try it in your second line:
user_input = gets.chomp
without String.
I hope it useful for you. :)
Your code is working as intended. You went wrong by running the code in your text editor instead of through the console. The Kernal#gets method requires user input, which would need to be mocked in order to run within your text-editor. Because your editor is returning nil instead of user input in string format, the chomp method is raising your NoMethodError.
Essentially your code is fine, but your are trying to run it in a limited environment. As a beginner, if your code requires user input, it's easier to test the code by running your ruby file through the console/terminal with ruby <filename.rb>.
This is just a sample method I have created for testing purpose using Ruby on Mac OSX 10.12 but I don't get the desired output: Can anyone suggest please? I tried getting the result using both paranthesis and without (). It doesn't even throw any error.
def hi
puts "Hello World"
End
hi
hi()
hi("Hello Matz")`
Try this:
def hi
puts "Hello World"
end
hi
hi()
And this:
def greet(greeting)
puts greeting
end
greet("Hello Matz")
Note that in this line:
hi("Hello Matz")`
you have a tick mark at the end, so that is an error:
1.rb:5: syntax error, unexpected tXSTRING_BEG, expecting end-of-input
It doesn't even throw any error.
Then you aren't running that program.
I suggest you open a Terminal window (Applications/Utilities/Terminal.app), and type in:
$ vimtutor
vim is a free computer programming editor that comes with your Mac. Do the tutorial and learn how to use vim. To run a ruby program, you enter your code into a file, then save it as, say, my_prog.rb. Then you need to give that file to ruby to execute it. You execute a ruby program like this:
$ ruby my_prog.rb
You can create a directory for all your ruby programs like this:
$ mkdir ruby_programs
$ cd ruby_programs
To create a new file inside that directory, use vim:
~/ruby_programs$ vi my_prog.rb
Once you are done typing in your code, save the file, which will put you back at the prompt in Terminal, then you can run your program:
~/ruby_programs$ ruby my_prog.rb
Once you get comfortable with vim, and you feel confident running your ruby programs, consider installing macvim with the vivid chalk color scheme:
It's nicer to look at than plain vim.
Try editing your file so that it reads:
def hi
puts "Hello World"
end
hi
Some important differences to note: def and end are both case-sensitive. The inside of the function definition is indented by two spaces. Since the function takes no arguments, no parentheses are necessary on the call to hi on line 4.
Depending on your filename, enter the command ruby FILENAME and you should see the output Hello World
Ruby keywords are case sensitive. Your code uses End and you probably wanted to use end to mark the end of the hi method.
Because End is not the same as end (and End is not a keyword), irb keeps waiting for input and treats the other three lines as part of the hi method. As far as it can tell, its definition is not complete until it reaches the end keyword (all non-capital letters.)
The correct way to define the method is:
def hi
puts "Hello World"
end
Then you can call it using either hi or hi().
Calling it as hi("Hello Matz") (or hi "Hello Matz") throws an ArgumentError exception with the message wrong number of arguments (given 1, expected 0) because it is called with one argument but the definition of method hi doesn't specify anything about arguments (by its definition, the method hi doesn't accept any argument).
When trying to delete a directory (+ contents) and after reading the files inside, FileUtils.rm_rf(path) will not delete all the folders, although it does delete all the files and some of the folders.
After some experimentation it seems to be related to a File.open block. (I actually do a regex match inside the block, but I'm just using a puts here to keep things clear)
File.open(file).each do |line|
puts line
end
From what I've read, the above should automatically close the file but when using this, FileUtils fails to complete its task.
However, if I use the following code, FileUtils works as desired.
open_file = File.open(file)
open_file.each do |line|
puts line
end
open_file.close
It's no big deal to use the code in the second example, but I do prefer the cleanliness of the first.
Is there any reason why that first example breaks FileUtils?
P.S. I'm new to both Ruby and Stack Overflow....Hi. My system is Ubuntu 11.04 (64bit), running RVM with Ruby 1.9.2-p180
You should use something like this:
File.open(file) do |f|
f.each{|line| puts line}
end
In your example the block is supplied to the each method and the version of open without a block is executed returning an IO object on which the each method is called.
I've installed the latest version of the stanfordparser and the ruby wrapper library for it. When trying to test it with a simple example from the website:
vi test.rb:
require "stanfordparser"
preproc =
StanfordParser::DocumentPreprocessor.new
puts
preproc.getSentencesFromString("This
is a sentence. So is this.")
ruby -rubygems test.rb
This
is
a
sentence
.
So
is
this
.
This is a sanity check really - am I doing something wrong, or is this a bug in the parser or wrapper?
You might be confused about how puts is formatting the output. Try this:
x = preproc.getSentencesFromString("This is a sentence. So is this.")
puts x.inspect
to make sure that you're getting what you're supposed to be getting.