Where to start?

thomthom

If you're new to Ruby I recommend "Ruby in Twenty Minutes": http://www.ruby-lang.org/en/documentation/quickstart/

As for SketchUp API, have a look at the sticky forum posts in this Developers section.

rumcajs

Yup. So it is similar to foreach (PHP and other languages that use that syntax like foreach ($arr as $key => $val ) {} ). Ruby is very similar to JQuery and Javascript.

thomthom

for key, value in array
  puts "#{key} - #{value}"
end

array.each { |key,value|
  http://www.thomthom.net/software/vertex_tools/manual
}

rumcajs

puts "Hello #{name.capitalize}!"

You can "add" any method to string inside string? That is awesome.

Class syntax:

class Greeter
def initialize(name = "World")
  @name = name
end
end

Does the class can have something like:

class Greeter
  @name = ""
  @myname = 
end

Or you cannot define variables outside method?

It looks like I have use initialize method to define instances before all

Is this @ used only in classed? I have seen using

@@time_start = Time.now

what does mean the @@?

thomthom

@rumcajs said:

puts "Hello #{name.capitalize}!"

You can "add" any method to string inside string? That is awesome.

That's string interpolation / it's the most efficient way to concatenate strings.

@rumcajs said:

what does mean the @@?

Class variable - single @ is instance variables. Have a look at the Ruby in Twenty minutes link. It goes through all the basics like this.

rumcajs

@thomthom said:

Have a look at the Ruby in Twenty minutes link. It goes through all the basics like this.

Yeah, I've just finished.

Is it only way of detecting if variable is array or do you have more ways? (inside class)


if @names.respond_to?("each")
end

rumcajs

I'm having a fun with this:
http://tryruby.org/levels/1/challenges/0#levels/1/challenges

This interactive guide for ruby is really cool. Somebody could make one for ruby beginners in SU, don't you think? It looks simple to do something like that.

thomthom

@rumcajs said:

@thomthom said:

Have a look at the Ruby in Twenty minutes link. It goes through all the basics like this.

Yeah, I've just finished.

Is it only way of detecting if variable is array or do you have more ways? (inside class)


> if @names.respond_to?("each")
> end

@names.is_a?( Enumerable )

Btw, - strings are slow, avoid them if you can. For respond_to?("each") use Symbols instead - like so: respond_to?(:each)

rumcajs

@thomthom said:

Btw, - strings are slow, avoid them if you can. For respond_to?("each") use Symbols instead - like so: respond_to?(:each)

Yes, I read it just now in the interactive guide I create my first hash. But don't know what is it hash, looks like an object... Why they call it hash?

thomthom

I take it you come from Javascript background?

Object have methods - Hashes has data.
A hash is an associative array - you specify the key and value. While with an array you just insert or remove values. (PHP and Javascript blends the difference between Hashes and Arrays. In Ruby they are distinct. ) Note that the order of the elements in arrays is based on the order they where added. When you iterate a Hash the values and keys is returned in a different order from how they where inserted.

rumcajs

OK. So summary.

Objects can keep properties (@name...) and methods.
Arrays [] are only non-associative.
Hashes {} are associative arrays, not ordered.

Can you print function or method just like in JS? I know more scripting languages not just JS. Last one is AHK.

rumcajs

I tried this (interactive guide):

ratings = Hash.new(0)
=> {}
Success!
> books.values.each { |rate| ratings[rate] += 1 }
=> [;splendid, ;quite_good, ;mediocre, ;quite_not_good, ;abysmal]
> ratings
=> {;splendid=>1, ;quite_good=>1, ;mediocre=>1, ;quite_not_good=>1, ;abysmal=>1}
>

And it is not clear to me, hoq the value 1 is assigned to the values. I guess that first command created new hash ratings. Then I go through each value of the hash and set the ratings... But how is it possible, that ratings hash overwrite the book.values? As I know this is problem in PHP. If you know something like

foreach(books->values as $val){ 
; this will not work;
val="new value";
}

It will not overwrite the for values of "values" property. Maybe the relation between ratings and books.values was already defined somewhere in a class, which is not visible to me?

This command does not work to me as expected:

.. File.Open("/Home/comics.txt", "a") do |f|
.... jjj
.. ss

I can write in the file but how to close it and to keep data in it? There should be some other stuff in the file when I write File.Open("/Home/comics.txt", "a") . Once I succeeded there were some links and they say, that is should add some data in file...

Dan Rathbun

@rumcajs said:

I tried this (interactive guide):

ratings = Hash.new(0)
> => {}
> Success!
> > books.values.each { |rate| ratings[rate] += 1 }
> => [;splendid, ;quite_good, ;mediocre, ;quite_not_good, ;abysmal]
> > ratings
> => {;splendid=>1, ;quite_good=>1, ;mediocre=>1, ;quite_not_good=>1, ;abysmal=>1}
> >

And it is not clear to me, how the value 1 is assigned to the values.

Because the Ruby interpreter changes the shorthand a += b, to a = a + b

So your statement:
books.values.each { |rate| ratings[rate] += 1 }

is actually executed as:
books.values.each { |rate| ratings[rate]= ratings[rate] + 1 }

Dan Rathbun

Method names begin with a lower case character (by convention.)

So it is:

` File.open("path/to/file","w") do |f|

end`

The block form of IO::open with automatically close the file handle.

rumcajs

Something else confused me. But i think I had overlooked something. The ratings are not saved in values, but in ratings...

Things are going bad, I cannot move on.


#<SyntaxError; Invalid char "\xC2" in expression. near line 1; "\xADread(\"/Hom\xC2\xADe/comics.t\xC2\xADxt\")">
> print File.read("/comics.txt")
=>
#<SyntaxError; Invalid char "\xC2" in expression. near line 1; "\xADread(\"/comics.t\xC2\xADxt\")">
> print File.read("comics.txt")
=>
#<Errno;;ENOENT; No such file or directory - comics.txt>
> Dir["/*"]
=> []
Open up a new BlogEntry class, pretty pretty please.
>

How can I print what is in /home/comics.txt and /comics.txt and if they exists and why this error happens...

rumcajs

Whatever i write it jumps into input mode:

comics.is_a
.. end
> comics.is_a?
..

Damn, that's not 15 minutes tutorial, but 15 hours (I'm in half but cannot move on).


> Popup.make do
.... h1 "Header"
.... list do
...... comics.each do |name, url|
........ link name, url
........ end
...... end
.... end
..

Should generate web page, but nothing popups. And I cannot check if the array exists, what is in array, what is in directory or if the file exist... Look like not realy ruby console (running in browser).

Dan Rathbun

defined?(comics)
tests for existance

comics.is_a?(Array)
or
comics.instance_of?(Array)
or
comics.class==(Array)
tests the class of the comics object

Dan Rathbun

@rumcajs said:

How can I print what is in /home/comics.txt and /comics.txt and if they exists and why this error happens...

You cannot assume that the current working directory is what you wish it to be (because another plugin may have changed it.)

Be sure a HOME environment var is defined on PC (it is always defined on Unix-like systems, such as OSX.)

unless RUBY_PLATFORM =~ /(darwin)/i
  ENV["HOME"]= ENV["USERPROFILE"] unless ENV["HOME"]
end


oldDir = Dir.getwd()
Dir.chdir(ENV["HOME"])

if File.exist?('comics.txt')
  lines = IO.readlines('comics.txt')
  puts(lines)
else
  puts("'comics.txt' could not be found.")
end

Dir.chdir(oldDir)

or use the **~** shortcut (if you KNOW that a HOME environment var is defined.)

filepath = File.expand_path('~/comics.txt')
if File.exist?(filepath)
  lines = IO.readlines(filepath)
  puts(lines)
else
  puts("'#{File.basename(filepath)}' could not be found in dir;\n#{File.dirname(filepath)}.")
end

Dan Rathbun

@rumcajs said:

Things are going bad, I cannot move on.

Because you NEED to read "Programming Ruby: The Pragmatic Programmer's Guide"

You need to take a WEEK OR MORE getting comfortable with Standard Ruby, before attempting to learn to use the SketchUp API.

I wrote the "Ruby Newbie's Guide to Getting Started" to help you and others avoid the frustration you are experiencing.

Follow the guide and you will be much happier.

thomthom

When it comes to the Ruby API I have a few articles on my blog - don't think they are liked in the sticky threads.

I recommend new plugin developers to read this one first: http://www.thomthom.net/thoughts/2012/01/golden-rules-of-sketchup-plugin-development/