selecting a variable number of individual items

[Joe Pizzanley]

I have a select field where I want to select a variable number of
individual items. How would I set up a def to handle this?

for example, one time I would select apples. Another time I would select
pears, plums and grapes.
I think that the code line: $ie.select_listname,
'FRUITS').select_value('plums') would vary in value and also in times
called, but that's as far as I can figure out.

(I can't call myself a newbie because I've been studying Ruby a long
time. I'm just not what you would call 'talented' with programming. I
guess I'm a ruby learner.)

Cheers, Joe

 

[Colin Bartlett]

[Note: parts of this message were removed to make it a legal post.]

I have a select field where I want to select a variable number of
individual items. How would I set up a def to handle this?

for example, one time I would select apples. Another time I would select
pears, plums and grapes.
I think that the code line: $ie.select_listname,
'FRUITS').select_value('plums') would vary in value and also in times
called, but that's as far as I can figure out.

(I can't call myself a newbie because I've been studying Ruby a long time.

I'm a bit hesitant to suggest this because you've been studying Ruby a long
time, and because I don't think I understand sufficiently what you want to
do. Do you want to do something like these:

class VarArgsExample
def select_example_using_variable_args( *args )
# now process the arguments to the method, for example
args.each do |v|
# do something with v
end
# maybe more processing
end

def select_example_using_array_arg( ary )
# a similar idea works for a hash argument
ary = [ary] unless ary.kind_of?( Array )
# now process the array values, for example
ary.each do |v|
# do something with v
end
# maybe more processing
end
end

obj = VarArgsExample.new

obj.select_example_using_variable_args( 'apples' )
obj.select_example_using_variable_args( 'pears', 'plums', 'grapes' )

obj.select_example_using_array_arg( 'apples' )
obj.select_example_using_array_arg( ['apples'] )
obj.select_example_using_array_arg( ['pears', 'plums', 'grapes'] )

 

[Joe Pizzanley]

I'm a bit hesitant to suggest this because you've been studying Ruby a
long time,

you're assuming that I've gotten good at it. It's still confusing to me
in many spots.

and because I don't think I understand sufficiently what you want to do.

the second half of your sentence is proof that I haven't gotten good at
it.


However your solution gave me enough to go on. I can push the arguments
into an array and then iterate through selecting whatever is in the
array.


thanks for extending help Colin! Much appreciated.

 

[Colin Bartlett]

[Note: parts of this message were removed to make it a legal post.]

you're assuming that I've gotten good at it. It's still confusing to me
in many spots.

the second half of your sentence is proof that I haven't gotten good at it.

Well, there is a difference between not knowing what you want to do, and
knowing what you want to do but not be able to explain what you want to do!

However your solution gave me enough to go on. I can push the arguments
into an array and then iterate through selecting whatever is in the array.
thanks for extending help Colin! Much appreciated.

No trouble: I wasn't sure what level to pitch any explanation at, and the
examples were aimed at what I thought you wanted to do - it seems that I
wasn't all that far off?

The following is a very simplified explanation of Ruby method arguments,
targetted at want you want to do. There's a longer (not quite up-to-date -
Ruby 1.9 allows more method argument options) explanation here:
http://ruby-doc.org/docs/ProgrammingRuby/html/tut_methods.html

class VarArgsExample
# example showing compulsory arguments, default arguments,
# and variable length arguments
def example_meth( arg0, arg1, arg2 = 222, arg3 = 333, *args )
puts "0=#{arg0.inspect}, 1=#{arg1.inspect}," \
" 2=#{arg2.inspect}, 3=#{arg3.inspect};" \
" var len args= #{args.inspect};"
"return value"
end
end

obj = VarArgsExample.new

obj.example_meth( ) rescue (p $!)
#=> #<ArgumentError: wrong number of arguments (0 for 2)>
obj.example_meth( 'apple' ) rescue (p $!)
#=> #<ArgumentError: wrong number of arguments (1 for 2)>
obj.example_meth( 'apple', 'fig' )
#=> 0="apple", 1="fig", 2=222, 3=333; var len args=[]
obj.example_meth( 'apple', 'fig', 'lemon' )
#=> 0="apple", 1="fig", 2="lemon", 3=333; var len args=[]
obj.example_meth( 'apple', 'fig', 'lemon', 'grape' )
#=> 0="apple", 1="fig", 2="lemon", 3="grape"; var len args=[]
obj.example_meth( 'apple', 'fig', 'lemon', 'grape', 'cherry' )
#=> 0="apple", 1="fig", 2="lemon", 3="grape"; var len args=["cherry"]
obj.example_meth( 'apple', 'fig', 'lemon', 'grape', 'cherry', 'blossom' )
#=> 0="apple", 1="fig", 2="lemon", 3="grape"; var len args=["cherry",
"blossom"]

For what you want do you can just do:
def select_values( *args )
# array args holds all the arguments passed to this method;
# and if you want to trap if no arguments were passed then
if args.size == 0 then
raise "select_values must have at least one argument"
end
end