Programming Forums > Script Programming > Ruby

Arevos · Apr 10th, 2006, 3:37 AM

This probably does the same thing:

class Array
    def max_by(&block)
        max { |a, b| block.call(a) <=> block.call(b) }
    end
end

Jessehk · Apr 10th, 2006, 3:48 PM

I'll best you one day, Arevos!

(In actuality, this was a case of me still discovering the available Enumerable methods

. )

Arevos · Apr 10th, 2006, 5:20 PM

A good way to approach these things is to assume that common functions exist and go from there. Ruby must have had some manner of max/min functions, so I just pulled up a Ruby language reference and searched for "max".

Educated guesses and dumb luck can turn up surprisingly efficient results, sometimes

Dietrich · Apr 11th, 2006, 10:18 PM

Found this cute little snippet:
[PHP]# just a teaser
print "Are you stupid? (yes or no) "
a = gets.to_s
if a == "yes"
puts "this is true"
else
puts "this is false"
end
gets # console wait[/PHP]
Also, Pythonistas beware!
[PHP]# function arg. defaults work in Python, but not in Ruby

def funk(a=2, b=3)
print "a=#{a} b=#{b}\n"
end

funk() # a=2 b=3

funk(a=1) # a=1 b=3

funk(b=1) # a=1 b=3 oops!

funk(a=12, b=13) # a=12 b=13[/PHP]

Master · Apr 12th, 2006, 8:33 AM

defualt values works in ruby

def doSomething(x = 10, y=4)
sprintf("%s %s",x,y)
end
doSomething() returns 10 and 4
doSomething(5) return 5 and 4
doSomething(6,7) return 6 and 7

when calling a function that has default values such as mine
you don't need to call doSomething(x = 5, y = 9) you simply do
doSomething(5,9)
x and y are just parameter which exist within the function not globally.
Your example use
funk(b=1) does not make it to call the b part of your function
but that code simply set b to 1 then pass b which is also = to 1 to the first parameter which is a locally to the function called funk then it changes a in the function to 1 then return the result. I think you are mixing default with something else or maybe you don't understand what is mean by default. here is a sample in C++

void doSomething(int x = 8, int y = 9)
{
std::cout << x << ","<<y;
}
when you call that you don't have to create a variable with the same name of the parameter, creating one then setting it to the function will not make no different
if i make int y outside of the function and set it to 70, then pass it to myfunction. it is interpreted as you passing 70 to the first parameter, not the second. the purpose of defualt value is simple makes it that you don't have to call every argument for the function call. it is just like having a defualt constructor in your program

sorry if i wrote too much or misunderstand what you said ^_^

Arevos · Apr 12th, 2006, 8:57 AM

I think Dietrich was just pointing out that, unlike Python, Ruby doesn't support named arguments to methods.

Dietrich · Apr 12th, 2006, 9:17 AM

Quote:

Originally Posted by Arevos

I think Dietrich was just pointing out that, unlike Python, Ruby doesn't support named arguments to methods.

Thanks Arevos, you have to know Python to fall for this potential mistake. Named arguments seem to be a nice feature that is missing in Ruby.

Master · Apr 12th, 2006, 3:53 PM

never mind i know what it mean now
http://diveintopython.org/power_of_i...arguments.html

Jessehk · Apr 12th, 2006, 4:02 PM

Quote:

Originally Posted by Master

never mind i know what it mean now
http://diveintopython.org/power_of_i...arguments.html

(Toggle Plain Text)

class Person:
    def __init__(self, name, age):
        self.name, self.age = name, age
    
p = Person(name="Jesse", age=15)

#or

p = Person(age=26, name="Joe")

I will admit that Ruby does not have named arguments, but it is planned for the 2.0 release.

EDIT

lease don't edit out a question, Master. It is really annoying for those answering it.

Dietrich · Apr 14th, 2006, 9:53 AM

Any wxPython (GUI) code in general uses a lot of named arguments. If Ruby does not have named arguments, then that explains why wxRuby code looks sooo different!

I looked at a hash as a workaround, but that has real problems too! It doesn't use the given default values.

(Toggle Plain Text)

# using a dictionary/hash container, still problems
def funk2(hash1 = {:a => 2, :b => 3}) 
  print "a=#{hash1[:a]}  b=#{hash1[:b]}\n" 
end 

funk2()     # a=2  b=3
funk2(:a=>1)  # a=1  b=  b should be 3 
funk2(:b=>1)  # a=  b=1  a should be 2 
funk2(:a=>12, :b=>13)  # a=12  b=13

Does anybody know how to do this right in Ruby, before the code looks alltogether too homely?

Apr 10th, 2006, 3:37 AM	#11
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 4	This probably does the same thing: (Toggle Plain Text) class Array def max_by(&block) max { \|a, b\| block.call(a) <=> block.call(b) } end end class Array def max_by(&block) max { \|a, b\| block.call(a) <=> block.call(b) } end end

Apr 10th, 2006, 3:48 PM	#12
Jessehk The Oblivious One Join Date: May 2005 Location: Ontario, Canada Posts: 630 Rep Power: 4	I'll best you one day, Arevos! (In actuality, this was a case of me still discovering the available Enumerable methods . ) __________________ Dr. Zoidberg: [ecstatic] I'm going to a movie... with FRIENDS!

Apr 11th, 2006, 10:18 PM	#14
Dietrich Professional Programmer Join Date: Feb 2005 Posts: 434 Rep Power: 4	Found this cute little snippet: [PHP]# just a teaser print "Are you stupid? (yes or no) " a = gets.to_s if a == "yes" puts "this is true" else puts "this is false" end gets # console wait[/PHP] Also, Pythonistas beware! [PHP]# function arg. defaults work in Python, but not in Ruby def funk(a=2, b=3) print "a=#{a} b=#{b}\n" end funk() # a=2 b=3 funk(a=1) # a=1 b=3 funk(b=1) # a=1 b=3 oops! funk(a=12, b=13) # a=12 b=13[/PHP] __________________ I looked it up on the Intergnats!

Apr 14th, 2006, 9:53 AM	#20
Dietrich Professional Programmer Join Date: Feb 2005 Posts: 434 Rep Power: 4	Any wxPython (GUI) code in general uses a lot of named arguments. If Ruby does not have named arguments, then that explains why wxRuby code looks sooo different! I looked at a hash as a workaround, but that has real problems too! It doesn't use the given default values. (Toggle Plain Text) # using a dictionary/hash container, still problems def funk2(hash1 = {:a => 2, :b => 3}) print "a=#{hash1[:a]} b=#{hash1[:b]}\n" end funk2() # a=2 b=3 funk2(:a=>1) # a=1 b= b should be 3 funk2(:b=>1) # a= b=1 a should be 2 funk2(:a=>12, :b=>13) # a=12 b=13 # using a dictionary/hash container, still problems def funk2(hash1 = {:a => 2, :b => 3}) print "a=#{hash1[:a]} b=#{hash1[:b]}\n" end funk2() # a=2 b=3 funk2(:a=>1) # a=1 b= b should be 3 funk2(:b=>1) # a= b=1 a should be 2 funk2(:a=>12, :b=>13) # a=12 b=13 Does anybody know how to do this right in Ruby, before the code looks alltogether too homely? __________________ I looked it up on the Intergnats! Last edited by Dietrich; Apr 14th, 2006 at 10:07 AM.

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Apr 10th, 2006, 5:20 PM	#13
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 4	A good way to approach these things is to assume that common functions exist and go from there. Ruby must have had some manner of max/min functions, so I just pulled up a Ruby language reference and searched for "max". Educated guesses and dumb luck can turn up surprisingly efficient results, sometimes

Apr 12th, 2006, 8:33 AM	#15
Master Programmer Join Date: Sep 2005 Location: GA Posts: 99 Rep Power: 3	defualt values works in ruby def doSomething(x = 10, y=4) sprintf("%s %s",x,y) end doSomething() returns 10 and 4 doSomething(5) return 5 and 4 doSomething(6,7) return 6 and 7 when calling a function that has default values such as mine you don't need to call doSomething(x = 5, y = 9) you simply do doSomething(5,9) x and y are just parameter which exist within the function not globally. Your example use funk(b=1) does not make it to call the b part of your function but that code simply set b to 1 then pass b which is also = to 1 to the first parameter which is a locally to the function called funk then it changes a in the function to 1 then return the result. I think you are mixing default with something else or maybe you don't understand what is mean by default. here is a sample in C++ void doSomething(int x = 8, int y = 9) { std::cout << x << ","<<y; } when you call that you don't have to create a variable with the same name of the parameter, creating one then setting it to the function will not make no different if i make int y outside of the function and set it to 70, then pass it to myfunction. it is interpreted as you passing 70 to the first parameter, not the second. the purpose of defualt value is simple makes it that you don't have to call every argument for the function call. it is just like having a defualt constructor in your program sorry if i wrote too much or misunderstand what you said ^_^

Apr 12th, 2006, 8:57 AM	#16
Arevos Programming Guru Join Date: Aug 2005 Location: England Posts: 1,499 Rep Power: 4	I think Dietrich was just pointing out that, unlike Python, Ruby doesn't support named arguments to methods.

Apr 12th, 2006, 3:53 PM	#18
Master Programmer Join Date: Sep 2005 Location: GA Posts: 99 Rep Power: 3	never mind i know what it mean now http://diveintopython.org/power_of_i...arguments.html

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