Named parameters

ruby-talk
1

Is there a way to write a function with named parameters?
Something like:

Header(‘title’ => “Somr Title”)

I gess one option is to use a hash and make the function call:

Header { ‘title’ => “Somr Title”}

Is there any other way?

How about default values for parameters? How can I do those?

Thanks a lot,
Daniel Carrera
Graduate Teaching Assistant. Math Dept.
University of Maryland. (301) 405-5137

2

Is there a way to write a function with named parameters?
Something like:

Header { ‘title’ => “Somr Title”}

Is there any other way?

Thi sis the way given in the Pickaxe.
http://ruby-central.com/book/tut_methods.html

How about default values for parameters? How can I do those?

Shown in the same page I gave above.

def foo(bar,baz=“Baz”)
puts “Foo, #{bar}, #{baz]”
end

foo(“hello”)

···

On Wed, 18 Dec 2002, Daniel Carrera wrote:

Foo, hello, Baz

As for combining the two - having default values for hash arguments
passed, that’s quite a bit tricker. only way I can think of is

def foo(params)
params[“baz”] = “Baz” unless params[“baz”]
params[“bar”] = “beer” unless params[“bar”]
…
end

The problem with this method is, if a programmer wants to pass ‘nil’ or
‘false’ or any non-true value as an argument, the default values would
overwrite that.

Hope that helps,
Greg

Thanks a lot,
Daniel Carrera
Graduate Teaching Assistant. Math Dept.
University of Maryland. (301) 405-5137

–
Greg Millam
walker at deafcode.com

3

Is there a way to write a function with named parameters?

Check out

http://www.rubygarden.org/ruby?KeywordArguments

It covers default and mandatory arguments as well.

Cheers,
Gavin

···

From: “Daniel Carrera” dcarrera@math.umd.edu

4

Gavin Sinclair wrote:

From: “Daniel Carrera” dcarrera@math.umd.edu

Is there a way to write a function with named parameters?

Check out

http://www.rubygarden.org/ruby?KeywordArguments

It covers default and mandatory arguments as well.

Cheers,
Gavin

Dan Berger also did a really good presentation on this topic at the Ruby
Conference. Hopefully those presentations will be available soon at the
RubyConf web site (or wherever).

5

Greg Millam wrote:

As for combining the two - having default values for hash arguments
passed, that’s quite a bit tricker. only way I can think of is

def foo(params)
params[“baz”] = “Baz” unless params[“baz”]
params[“bar”] = “beer” unless params[“bar”]
…
end

The problem with this method is, if a programmer wants to pass ‘nil’ or
‘false’ or any non-true value as an argument, the default values would
overwrite that.

def foo(params)
{:argA => “default A”, :argB => “default B”}.update params
end

p foo(:argA=>nil) # ==> {:argA=>nil, :argB=>“default B”}

6

Lyle Johnson wrote:

Gavin Sinclair wrote:

From: “Daniel Carrera” dcarrera@math.umd.edu

Is there a way to write a function with named parameters?

Check out

http://www.rubygarden.org/ruby?KeywordArguments

It covers default and mandatory arguments as well.

Cheers,
Gavin

Dan Berger also did a really good presentation on this topic at the Ruby
Conference. Hopefully those presentations will be available soon at the
RubyConf web site (or wherever).

Thanks Lyle. :slight_smile:

It was my impression Ryan Davis was going to put them up somewhere at some
point, but I haven’t seen them posted.

Ryan? Any word?

Regards,

Dan