I'm learning about Qt Model/View with Ruby and I'm trying run the following code
require 'Qt4'
class MyModel < Qt::AbstractListModel
def initialize(data = [])
super()
#data = data
end
def rowCount idx
#data.size
end
def data idx, role = Qt::DisplayRole
if role == Qt::DisplayRole then
Qt::Variant.new #data
else Qt::Variant.new
end
end
end
if $0 == __FILE__
app = Qt::Application.new ARGV
v = Qt::ListView.new
m = MyModel.new(['1', '2', '3'])
v.model = m
v.show
app.exec
end
When I run the script what it shows is a list window with three rows empty. What am I doing wrong?
On the other hands, I find it hard to learn to model/view programming with ruby due to the poor documentation (All is C++) anyone know if there are tutorials or something?
Are you familiar with Qt, Ruby and/or C++ already? If so that'll help hugely on your journey as there isn't unfortunately that much documentation for Qt with Ruby available.
Anyway, the problem is that you're returning an Array instead of the element for the wanted index, see QAbstractItemModel::data. The idx argument in there is a QModelIndex, so just look up the wanted row and return it like this:
Qt::Variant.new #data[idx.row]
Also, checkout http://techbase.kde.org/Development/Languages/Ruby for information regarding to Ruby & Qt in general.
Related
Ruby OOP beginner here. Trying to build a simple Vending machine code.
class VendingMachine
# TODO: add relevant getter/setter to this class to make the scenarios work properly.
attr_reader :snack_price_cents, :user_balance_cents
attr_accessor :snack_count
def initialize(snack_price_cents, snack_count)
#user_balance_cents = 0
#snack_count = snack_count
#snack_price_cents = snack_price_cents
end
def insert_coin(input_cents)
#user_balance_cents = user_balance_cents + input_cents if input_cents
end
def buy_snack
if snack_count.zero? || user_balance_cents.zero?
#snack_count = snack_count
else
#snack_count = snack_count - 1
#user_balance_cents = user_balance_cents - snack_price_cents
end
end
end
I am trying to understand what happens to snack_count, user_balance_cents and snack_price_cents when the user pushes a button to buy a snack?
It seems like all is working okay except for the user_balance_cents but I am getting:
should not let you buy a snack if you didn't insert enough money (error path) (FAILED - 1)"
error. Any help?
I would guess that your error here is that you are checking that user_balance_cents is not zero, but you are not checking that it as least snack_price_cents.
i.e. if I put 10c in and try to buy a 50c snack, it will give me it.
I would like to know whether I can get source code a method on the fly, and whether I can get which file is this method in.
like
A.new.method(:a).SOURCE_CODE
A.new.method(:a).FILE
Use source_location:
class A
def foo
end
end
file, line = A.instance_method(:foo).source_location
# or
file, line = A.new.method(:foo).source_location
puts "Method foo is defined in #{file}, line #{line}"
# => "Method foo is defined in temp.rb, line 2"
Note that for builtin methods, source_location returns nil. If want to check out the C source code (have fun!), you'll have to look for the right C file (they're more or less organized by class) and find the rb_define_method for the method (towards the end of the file).
In Ruby 1.8 this method does not exist, but you can use this gem.
None of the answers so far show how to display the source code of a method on the fly...
It's actually very easy if you use the awesome 'method_source' gem by John Mair (the maker of Pry):
The method has to be implemented in Ruby (not C), and has to be loaded from a file (not irb).
Here's an example displaying the method source code in the Rails console with method_source:
$ rails console
> require 'method_source'
> I18n::Backend::Simple.instance_method(:lookup).source.display
def lookup(locale, key, scope = [], options = {})
init_translations unless initialized?
keys = I18n.normalize_keys(locale, key, scope, options[:separator])
keys.inject(translations) do |result, _key|
_key = _key.to_sym
return nil unless result.is_a?(Hash) && result.has_key?(_key)
result = result[_key]
result = resolve(locale, _key, result, options.merge(:scope => nil)) if result.is_a?(Symbol)
result
end
end
=> nil
See also:
https://rubygems.org/gems/method_source
https://github.com/banister/method_source
http://banisterfiend.wordpress.com/
Here is how to print out the source code from ruby:
puts File.read(OBJECT_TO_GET.method(:METHOD_FROM).source_location[0])
Without dependencies
method = SomeConstant.method(:some_method_name)
file_path, line = method.source_location
# puts 10 lines start from the method define
IO.readlines(file_path)[line-1, 10]
If you want use this more conveniently, your can open the Method class:
# ~/.irbrc
class Method
def source(limit=10)
file, line = source_location
if file && line
IO.readlines(file)[line-1,limit]
else
nil
end
end
end
And then just call method.source
With Pry you can use the show-method to view a method source, and you can even see some ruby c source code with pry-doc installed, according pry's doc in codde-browing
Note that we can also view C methods (from Ruby Core) using the
pry-doc plugin; we also show off the alternate syntax for show-method:
pry(main)> show-method Array#select
From: array.c in Ruby Core (C Method):
Number of lines: 15
static VALUE
rb_ary_select(VALUE ary)
{
VALUE result;
long i;
RETURN_ENUMERATOR(ary, 0, 0);
result = rb_ary_new2(RARRAY_LEN(ary));
for (i = 0; i < RARRAY_LEN(ary); i++) {
if (RTEST(rb_yield(RARRAY_PTR(ary)[i]))) {
rb_ary_push(result, rb_ary_elt(ary, i));
}
}
return result;
}
I created the "ri_for" gem for this purpose
>> require 'ri_for'
>> A.ri_for :foo
... outputs the source (and location, if you're on 1.9).
GL.
-r
Internal methods don't have source or source location (e.g. Integer#to_s)
require 'method_source'
User.method(:last).source
User.method(:last).source_location
I had to implement a similar feature (grab the source of a block) as part of Wrong and you can see how (and maybe even reuse the code) in chunk.rb (which relies on Ryan Davis' RubyParser as well as some pretty funny source file glomming code). You'd have to modify it to use Method#source_location and maybe tweak some other things so it does or doesn't include the def.
BTW I think Rubinius has this feature built in. For some reason it's been left out of MRI (the standard Ruby implementation), hence this hack.
Oooh, I like some of the stuff in method_source! Like using eval to tell if an expression is valid (and keep glomming source lines until you stop getting parse errors, like Chunk does)...
I have a ruby (sinatra) app that I am working on, and my input is a url and if verbose or not (true or false), so basically like this:
The url would look like this: http://localhost:4567/git.company.com&v=false for example.
And the code to fetch those is this:
get '/:url' do |tool_url|
url = params[:url].to_s
is_verbose = params[:v].to_s
I have different classes separated in different files and I'm including them into my main script like this:
Dir["#{File.dirname(__FILE__)}/lib/*.rb"].each { |f| require(f) }
(And a sample file would be something like this), gitlab.rb:
class Gitlab
$gitlab_token = 'TOKEN_GOES_HERE'
def initialize(url, v)
##regex =~ /git.company.com/
##gitlab_url = url
##is_verbose = v
end
def check_gitlab(gitlab_url, is_verbose)
_gitlab_overall = '/health_check.json?token=#{gitlab_token}'
_gitlab_cache = '/health_check/cache.json?token=#{gitlab_token}'
_gitlab_database = '/health_check/database.json?token=#{gitlab_token}'
_gitlab_migrations = '/health_check/migrations.json?token=#{gitlab_token}'
unless is_verbose = true
CheckString.check_string_from_page('https://' + gitlab_url + gitlab_overall, 'success')
else
end
end
end
Now, I want to be able to dynamically know which "class" to use to do a certain job based on the URL that's entered by the user, so my idea was to iterate through those classes looking for a particular variable to match with the input.
I need guidance in this because I've been stuck on this for quite some time now; I've tried so many things that I can think of, but none worked.
Disclaimer: Please bear with me here, because I'm very new to Ruby and I'm not that great in OOP languages (haven't really practiced them that much).
EDIT: I'm open to any suggestion, like if there's a different logic that's better than this, please do let me know.
Make a hash { Regexp ⇒ Class }:
HASH = {
/git.company.com/ => Gitlab,
/github.com/ => Github
}
and then do:
handler = HASH.detect { |k, _| k =~ url }.last.new
The above will give you an instance of the class you wanted.
Sidenotes:
is_verbose = params[:v].to_s always results in is_verbose set to truthy value, check for params[:v].to_s == "true"
is_verbose = true is an assignment, you wanted to use just unless is_verbose.
To make it runtime-resolving, force the plugins to a) include Plugin and b) declare resolve method. Plugin module should define a callback hook:
module Plugin
def self.included(base)
Registry::HASH[-> { base.resolve }] = base
end
end
resolve method should return a regexp, the lambda is here to make it resolved on parsing stage:
class PluginImpl
include Plugin
def resolve
/git.company.com/
end
end
And then match when needed:
handler = HASH.detect { |k, _| k.() =~ url }.last.new
Other way round would be to use ObjectSpace to detect classes, including the module, or declare the TracePoint on base in included callback to provide a direct map, but all this is overcomplicating.
im trying to optimize my code as much as possible and i've reached a dead end.
my code looks like this:
class Person
attr_accessor :age
def initialize(age)
#age = age
end
end
people = [Person.new(10), Person.new(20), Person.new(30)]
newperson1 = [Person.new(10)]
newperson2 = [Person.new(20)]
newperson3 = [Person.new(30)]
Is there a way where i can get ruby to automatically pull data out from the people array and name them as following newperson1 and so on..
Best regards
That is definitely a code smell. You should refer to them as [people[0]], [people[1]], ... .
But if you insist on doing so, and if you can wait until December 25 (Ruby 2.1), then you can do:
people.each.with_index(1) do |person, i|
binding.local_variable_set("newperson#{i}", [person])
end
I think this is what you're trying to do...
newperson1 = people[0]
puts newperson1.age
The output of this 10 as expected.
I would like to know whether I can get source code a method on the fly, and whether I can get which file is this method in.
like
A.new.method(:a).SOURCE_CODE
A.new.method(:a).FILE
Use source_location:
class A
def foo
end
end
file, line = A.instance_method(:foo).source_location
# or
file, line = A.new.method(:foo).source_location
puts "Method foo is defined in #{file}, line #{line}"
# => "Method foo is defined in temp.rb, line 2"
Note that for builtin methods, source_location returns nil. If want to check out the C source code (have fun!), you'll have to look for the right C file (they're more or less organized by class) and find the rb_define_method for the method (towards the end of the file).
In Ruby 1.8 this method does not exist, but you can use this gem.
None of the answers so far show how to display the source code of a method on the fly...
It's actually very easy if you use the awesome 'method_source' gem by John Mair (the maker of Pry):
The method has to be implemented in Ruby (not C), and has to be loaded from a file (not irb).
Here's an example displaying the method source code in the Rails console with method_source:
$ rails console
> require 'method_source'
> I18n::Backend::Simple.instance_method(:lookup).source.display
def lookup(locale, key, scope = [], options = {})
init_translations unless initialized?
keys = I18n.normalize_keys(locale, key, scope, options[:separator])
keys.inject(translations) do |result, _key|
_key = _key.to_sym
return nil unless result.is_a?(Hash) && result.has_key?(_key)
result = result[_key]
result = resolve(locale, _key, result, options.merge(:scope => nil)) if result.is_a?(Symbol)
result
end
end
=> nil
See also:
https://rubygems.org/gems/method_source
https://github.com/banister/method_source
http://banisterfiend.wordpress.com/
Here is how to print out the source code from ruby:
puts File.read(OBJECT_TO_GET.method(:METHOD_FROM).source_location[0])
Without dependencies
method = SomeConstant.method(:some_method_name)
file_path, line = method.source_location
# puts 10 lines start from the method define
IO.readlines(file_path)[line-1, 10]
If you want use this more conveniently, your can open the Method class:
# ~/.irbrc
class Method
def source(limit=10)
file, line = source_location
if file && line
IO.readlines(file)[line-1,limit]
else
nil
end
end
end
And then just call method.source
With Pry you can use the show-method to view a method source, and you can even see some ruby c source code with pry-doc installed, according pry's doc in codde-browing
Note that we can also view C methods (from Ruby Core) using the
pry-doc plugin; we also show off the alternate syntax for show-method:
pry(main)> show-method Array#select
From: array.c in Ruby Core (C Method):
Number of lines: 15
static VALUE
rb_ary_select(VALUE ary)
{
VALUE result;
long i;
RETURN_ENUMERATOR(ary, 0, 0);
result = rb_ary_new2(RARRAY_LEN(ary));
for (i = 0; i < RARRAY_LEN(ary); i++) {
if (RTEST(rb_yield(RARRAY_PTR(ary)[i]))) {
rb_ary_push(result, rb_ary_elt(ary, i));
}
}
return result;
}
I created the "ri_for" gem for this purpose
>> require 'ri_for'
>> A.ri_for :foo
... outputs the source (and location, if you're on 1.9).
GL.
-r
Internal methods don't have source or source location (e.g. Integer#to_s)
require 'method_source'
User.method(:last).source
User.method(:last).source_location
I had to implement a similar feature (grab the source of a block) as part of Wrong and you can see how (and maybe even reuse the code) in chunk.rb (which relies on Ryan Davis' RubyParser as well as some pretty funny source file glomming code). You'd have to modify it to use Method#source_location and maybe tweak some other things so it does or doesn't include the def.
BTW I think Rubinius has this feature built in. For some reason it's been left out of MRI (the standard Ruby implementation), hence this hack.
Oooh, I like some of the stuff in method_source! Like using eval to tell if an expression is valid (and keep glomming source lines until you stop getting parse errors, like Chunk does)...