I am trying to declare a class with a few basic functions in it. The function that seems to be causing a problem has an optional argument that passes a symbol in.
class Bag < RandomizerCollection
def initialize()
end
def select(description:Hash, amt=:all)
end
def empty()
end
end
And the error I am getting is:
Traceback (most recent call last):
1: from test.rb:5:in `<main>'
test.rb:5:in `require_relative': /home/osboxes/Documents/Year4/Design/A1/Bag.rb:9: syntax error, unexpected tIDENTIFIER (SyntaxError)
...ef select(description:hash, amt = :all)
... ^~~
/home/osboxes/Documents/Year4/Design/A1/Bag.rb:9: syntax error, unexpected ')', expecting keyword_end
...t(description:hash, amt = :all)
I'm sure this must be something basic but I just can't figure it out. I am new to Ruby and I found similar questions but none helped me find the issue. Any help is appreciated!
You can't define optional arguments (arg=value) after the definition of the keyword arguments (arg: value).
You can correct it in two ways:
Move optional arg before the keywor arg:
def select(amt=:all, description:Hash)
end
Make the second argument a keyword arg:
def select(description:Hash, amt: :all)
end
Worth reading: https://medium.com/podiihq/ruby-parameters-c178fdcd1f4e
Related
I'm trying to create 2 routes dynamically for the same url but it says
syntax error, unexpected ',', expecting keyword_end (SyntaxError)
for this code:
[:get, :options].each do |x|
send(x), '/my_url' do
# ....
end
end
What am I doing wrong?
The '/my_url' is a parameter of the get function, so it needs to be a parameter of the send function:
send(x, '/my_url') do
# ...
end
I'm going through Ruby Koans, and I"m getting hung up on the test_every_object_has_an_id method in about_objects.rb. The supplied code reads like so:
def test_every_object_has_an_id
obj = Object.new
assert_equal __, obj.object_id.class
end
I know that the answer is Fixnum, but, whenever I run path_to_enlightenment.rb, I get the following error message:
custom_require.rb:36:in `require':about_objects.rb:50: syntax error, unexpected $end, expecting keyword_end (SyntaxError) from rubygems/custom_require.rb:36:in `require'
from path_to_enlightenment.rb:7:in `<main>'
Is there some sort of bug in the code as supplied, or am I doing something wrong?
Missing end Keyword
Somewhere else in your files you have a missing end keyword. Some file is reaching the end of the source file before finding the expected keyword. The error clearly tells you so:
custom_require.rb:36:in `require':about_objects.rb:50: syntax error, unexpected $end, expecting keyword_end (SyntaxError) from rubygems/custom_require.rb:36:in `require' from path_to_enlightenment.rb:7:in `<main>'
Check lines 7, 36, and 50 of the named files. That's the problem you need to fix, and has nothing to do with the fact that:
Object.new.object_id.class
#=> Fixnum
It doesn't ask you which class it is, it ask what Fixnum class is. So the answer must be Object
>> Object.new.object_id.class.is_a? Fixnum
#=> false
>> Object.new.object_id.class.is_a? Object
#=> true
The error is:
C:/Users/Admin/Desktop/MyFirstSelfMadeGame.rb:18: syntax error, unexpected keyword_end, expecting $end
Code:
#!/usr/bin/env ruby
require "gosu"
class GameWindow < Gosu::Window
def initialize(800, 600, false) #Window declaration
super
self.caption("Pokemon")
end
def update
end
def draw
end
def button_down(id)
close if id == Gosu::KbSpace
end
end
GameWindow.new.show
Thanks for answers, i get this problem alot.
No, this is not the whole error, the whole error looks something like:
t.rb:6: syntax error, unexpected tINTEGER, expecting ')'
def initialize(800, 600, false) #Window declaration
^
t.rb:21: syntax error, unexpected kEND, expecting $end
Please note that there are 2 error messages reported by the Ruby interpreter. You have noticed and posted only the 2nd one, but the 1st one is actually the relevant one. In general, if you receive error messages, it's a good rule of thumb to find and fix the 1st one first, because the subsequent ones may be caused by the first one.
You need to specify for function arguments. Incorrect:
def initialize(800, 600, false) #Window declaration
Correct:
def initialize()
super(800, 600, false)
As pts says, you cannot reference objects in a method definition arguments
The method definition arguments should only contain variables that you reference in the method.
If you want to use defaults but have the option to override the arguments when calling the 'new' method you could do...
def initialize(width=800, height=600, full_screen=false)
super(width, height, full_screen)
Also, you should note that self.caption is a getter method and doesn't take arguments
this is wrong
self.caption("Pokemon") # < wrong
this is right
self.caption = "Pokemon" # < right
Take a look at the tutorial game...
https://github.com/jlnr/gosu/wiki/Ruby-Tutorial
I am working on a RoR project, and I want to know if I can use end as a method name. It seems to work fine, but I would like to know if this method will bring any issues in the future. I tried and it works:
class Dany
def end
puts 'Hola'
end
end
and this is the output:
Dany.new.end # => Hola
Ruby let's you do this, but you're going to run into all sorts of issues.
# end.rb
class Dany
def end
puts "Hola"
end
def other
end # should puts Hola
end
end
Instead, you will get
end.rb:10: syntax error, unexpected keyword_end, expecting end-of-input
Bottom line: don't do this. Don't use any keywords as a method name.
It is not a good idea to use a keyword as a method name, but as long as you disambiguate the token as a method call, you can use it. It is not practical though.
Dany.new.instance_eval{self.end} # => Hola
Dany.new.send(:end) # => Hola
Dany.new.method(:end).call # => Hola
Dany.new.instance_eval{end} # => syntax error, unexpected keyword_end
The usual disambiguation using () does not seem to work for this case, making it complicated.
Dany.new.instance_eval{end()} # => syntax error, unexpected keyword_end
I found this weirdness that I would like to understand. If I define these two methods in pry...
def test(*args)
puts args
end
def test=(*args)
puts args
end
they both work.But if I put the above code in a module and include that module in another class (say, class Job), the following
j=Job.last
j.test=(1,2,3)
throws the following error...
SyntaxError: (irb):3: syntax error, unexpected ',', expecting ')'
j.test=(1,2,3)
^
The following work as expected...
j.test=[1,2,3]
j.test=(1)
So, it looks like inside the module, a method defined with an '=' always expects one arg. That doesn't make sense to me.
What am I missing
Parsing of the Ruby interpreter. Try
j.send :test=, 1, 2, 3
use directly
j.test = 1,2,3
or
j.test= ([1,2,3])
or `
j.send('test=',[1,2,3])