Re: [Rails-core] Proposal for def_method_missing in ActiveSupport

[Ryan Bigg]

-1

I don't think this feature would be useful to the majority of Rails developers out there, sorry.

You could always release it as a separate gem and get people to use it that way.

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Ryan Bigg

On Friday, 10 August 2012 at 0:59, Stephen Touset wrote:

In several places in Rails (e.g., ActiveRecord `find_by_#{attr2}_and_#{att2}` methods), you override `method_missing` to provide functionality. In all of those places, you follow the sane approach of handling `respond_to?` as well as actually defining the method body for future callers.

I've abstracted this logic out into a project called def_method_missing[1]. Examples:

class Foo

# regexp matchers yield the MatchData to the block, so you can modify the method

# body based on the regexp

def_method_missing /bar/ do |match|

-> { match.pre_match }

end

# without a regexp matcher, the name of the method is passed to the block, allowing

# you to decide whether or not to implement the method

def_method_missing do |name|

-> { name } if name.length == 4

-> { "bang!" } if name[-1] == '!'

end

end

foo = Foo.new

# regexp-based method_missing

foo.respond_to?(:bazbar) # => true

foo.bazbar # => "baz"

foo.methods.include? /bazbaz/ # => true

# arbitrary Ruby method_missing

foo.respond_to?(:wat) # => false

foo.respond_to?(:what) # => true

foo.what # => :what

foo.methods.include?(:what) # => true

foo.bang # => :bang # matches four-character method name

foo.bang! # => "bang!" # matches last-character bang

foo.wat! # => :wat! # matches four-character method name first

Is this something you'd be willing to consider including in ActiveSupport? Obviously, I'll have to put the logic into its own Module to avoid polluting default `Object`s and `Module`s. Plus documentation/tests. The current implementation was just a concept I threw together a few months back and promptly forgot about.

[1]: https://github.com/stouset/def_method_missing

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[Stephen Touset]

Yes. However, this is something currently implemented *in* Rails already (e.g., `SomeModel#find_by_foo_and_bar_and_baz`). Rails itself could benefit from the abstraction being put into ActiveSupport.