Call a Function

Hello,

I currently have an array of strings. Let's say, for example, my array contains the following:

                            ['one', 'two', 'three']

Each element in my array is the name of a function in my program. I want to call the functions, using the array element. So for example, lets say that my array is named 'numArray'. I want to call the function in my program named 'one'. I am now trying numArray[0]. Is there a way to make the numArray[0] be recognized as 'one' and call the function? If my question is not clear, I can elaborate. Thanks in advance for all help.

- Shelton

···

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Jason Shelton wrote:

I currently have an array of strings. Let's say, for example, my array
contains the following:

                            ['one', 'two', 'three']

Each element in my array is the name of a function in my program. I want
to call the functions, using the array element.

Object#send is the method you want. It takes a method name (follows by a list
of arguments, if there are any) as an argument and calls that method on the
receiver.

HTH,
Sebastian

···

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Jabber: sepp2k@jabber.org
ICQ: 205544826

Hello,

I currently have an array of strings. Let's say, for example, my array contains the following:

                           ['one', 'two', 'three']

Each element in my array is the name of a function in my program. I want to call the functions, using the array element. So for example, lets say that my array is named 'numArray'. I want to call the function in my program named 'one'. I am now trying numArray[0]. Is there a way to make the numArray[0] be recognized as 'one' and call the function? If my question is not clear, I can elaborate. Thanks in advance for all help.

Convert the string to a symbol and send it to the appropriate object.

   > send( numArray[0].to_sym )
   => NoMethodError: undefined method 'one' for main:Object

   > def one; puts "One!"; end
   => nil

   > send( numArray[0].to_sym )
   One!
   => nil

···

On Feb 3, 2009, at 3:39 PM, Jason Shelton wrote:

Use "eval".

irb(main):001:0> def one
irb(main):002:1> puts "1"
irb(main):003:1> end
=> nil
irb(main):004:0> def two
irb(main):005:1> puts "2"
irb(main):006:1> end
=> nil
irb(main):007:0> metharray = ['one', 'two']
=> ["one", "two"]
irb(main):008:0> metharray.each { |e| eval e }
1
2
=> ["one", "two"]

···

On Tue, Feb 3, 2009 at 4:39 PM, Jason Shelton <jas.shelton@hotmail.com> wrote:

Hello,

I currently have an array of strings. Let's say, for example, my array contains the following:

                           ['one', 'two', 'three']

Each element in my array is the name of a function in my program. I want to call the functions, using the array element. So for example, lets say that my array is named 'numArray'. I want to call the function in my program named 'one'. I am now trying numArray[0]. Is there a way to make the numArray[0] be recognized as 'one' and call the function? If my question is not clear, I can elaborate. Thanks in advance for all help.

- Shelton
_________________________________________________________________
Windows Live™ Hotmail(R):…more than just e-mail.
http://windowslive.com/explore?ocid=TXT_TAGLM_WL_t2_hm_justgotbetter_explore_012009

Convert the string to a symbol and send it to the appropriate object.

That isn't even necessary, sending a string works just as fine.

···

--
Dominik Honnef
dominikho@gmx.net

Hi --

···

On Wed, 4 Feb 2009, Matthew Moss wrote:

On Feb 3, 2009, at 3:39 PM, Jason Shelton wrote:

Hello,

I currently have an array of strings. Let's say, for example, my array contains the following:

                          ['one', 'two', 'three']

Each element in my array is the name of a function in my program. I want to call the functions, using the array element. So for example, lets say that my array is named 'numArray'. I want to call the function in my program named 'one'. I am now trying numArray[0]. Is there a way to make the numArray[0] be recognized as 'one' and call the function? If my question is not clear, I can elaborate. Thanks in advance for all help.

Convert the string to a symbol and send it to the appropriate object.

No need to convert it. send will take a string.

David

--
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Ruby/Rails consulting & training: http://www.rubypal.com
Coming in 2009: The Well-Grounded Rubyist (http://manning.com/black2\)

http://www.wishsight.com => Independent, social wishlist management!

Use "eval".

No, please do not.
Using eval is not necessary *most* of the time, especially in this
case where you got the send method.

···

--
Dominik Honnef
dominikho@gmx.net

Wouldn't you have to pass in the calling context (self from the callers pov) if you were deffing your methods without a class? Ie needs to k ow the object to send on, no? :slight_smile:

Blog: http://random8.zenunit.com/
Learn rails: http://sensei.zenunit.com/

···

On 04/02/2009, at 8:46 AM, Sebastian Hungerecker <sepp2k@googlemail.com> wrote:

Jason Shelton wrote:

I currently have an array of strings. Let's say, for example, my array
contains the following:

                           ['one', 'two', 'three']

Each element in my array is the name of a function in my program. I want
to call the functions, using the array element.

Object#send is the method you want. It takes a method name (follows by a list
of arguments, if there are any) as an argument and calls that method on the
receiver.

HTH,
Sebastian
--
NP: Die Apokalyptischen Reiter - Nach Der Ebbe
Jabber: sepp2k@jabber.org
ICQ: 205544826

Yeah, after the fact, I tried it like you say. For some reason, I had the impression that strings didn't auto-convert to symbols.

···

On Feb 3, 2009, at 4:00 PM, Dominik Honnef wrote:

Convert the string to a symbol and send it to the appropriate object.

That isn't even necessary, sending a string works just as fine.

Julian Leviston wrote:

Wouldn't you have to pass in the calling context (self from the
callers pov) if you were deffing your methods without a class?

self from the callers pov is also self from send's pov if you invoke it
without an explicit receiver. So no, you don't.

HTH,
Sebastian

···

--
Jabber: sepp2k@jabber.org
ICQ: 205544826

Hi --

···

On Wed, 4 Feb 2009, Matthew Moss wrote:

On Feb 3, 2009, at 4:00 PM, Dominik Honnef wrote:

Convert the string to a symbol and send it to the appropriate object.

That isn't even necessary, sending a string works just as fine.

Yeah, after the fact, I tried it like you say. For some reason, I had the impression that strings didn't auto-convert to symbols.

The documentation is misleading; it specifies the argument as a
symbol, but it can be either. (And I consider that a feature; I don't
think it's just working by chance.)

David

--
David A. Black / Ruby Power and Light, LLC
Ruby/Rails consulting & training: http://www.rubypal.com
Coming in 2009: The Well-Grounded Rubyist (http://manning.com/black2\)

http://www.wishsight.com => Independent, social wishlist management!