Use Module#prepend where possible

[mikker]

This leaves us with only the module based APIs still using class_eval, specifically delayed_job and sucker_punch. The problem being that at the time of hooking up the integration, the target modules have already been included and so prepending doesn't modify the including classes.

I propose we leave them as is for now and change them in a future version if we come up with a scheme or they introduce some sort of plugin api that could help us avoid class_eval.

This PR is a breaking change not because it removes any features but because it might interfere with other libraries still using class_eval and thereby possibly introduce the infinite loop when trying to look up stacktraces after an exception(#753 for example).

[ghost]

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• Build Cause: [Pull request #890 updated]

• Start Time: 2020-11-19T20:12:43.757+0000

• Duration: 22 min 42 sec

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• Description: [2020-11-19T20:16:46.951Z] + ./spec/scripts/spec.sh docker.elastic.co/observability-ci/jruby:9.2-13-

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• Description: [2020-11-19T20:17:16.349Z] + ./spec/scripts/spec.sh docker.elastic.co/observability-ci/jruby:9.2-13-

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• Description: [2020-11-19T20:17:25.758Z] + ./spec/scripts/spec.sh docker.elastic.co/observability-ci/jruby:9.1-7-j

[mikker]

😅

apm-agent-ruby/lib/elastic_apm/span_helpers.rb

Lines 39 to 49 in 9557a3c

	klass.prepend(Module.new do
	define_method(method) do |*args|
	unless ElasticAPM.current_transaction
	return super(*args)
	end
	ElasticAPM.with_span "#{name}", "#{type}" do
	super(*args)
	end
	end
	end)

[estolfo]

Looks good-- seems a lot more straightforward than I thought it would be.
You mentioned wanting to change the name of Spies, do you still want to? We could call them extensions, as they are each in a module Ext. Or integrations, as I think you suggested.

[mikker]

I sort of still do. We'd have to do it in 2 steps though as we'd be renaming some config options too. So step 1 is soft deprecation, then remove in major.

[estolfo]

ok, I guess it's not urgent then and doesn't necessarily have to be part of this PR.