[ruby-core:90302] [Ruby trunk Feature#15287] New TracePoint events to support loading features

[ko1@atdot.net]

Issue #15287 has been updated by ko1 (Koichi Sasada).


Matz agreed about naming of "script_compiled".

If others especially English natives have ideas, please tell me.
If no, I'll commit "script_compiled" event some days later.

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I'm reconsidering "method_added" event because there are several other points we change the class/module methods. We already has several hooks provided by method hook:

```C
    rb_define_private_method(rb_cClass, "inherited", rb_obj_dummy, 1);
    rb_define_private_method(rb_cModule, "included", rb_obj_dummy, 1);
    rb_define_private_method(rb_cModule, "extended", rb_obj_dummy, 1);
    rb_define_private_method(rb_cModule, "prepended", rb_obj_dummy, 1);
    rb_define_private_method(rb_cModule, "method_added", rb_obj_dummy, 1);
    rb_define_private_method(rb_cModule, "method_removed", rb_obj_dummy, 1);
    rb_define_private_method(rb_cModule, "method_undefined", rb_obj_dummy, 1);
```

Maybe other events we want to introduce. But (this is internal reason) we don't have enough bits to represent them.

There are several ideas:

* (1) add all events above (change internal)
* (2) add one event (`extended`, for example) and add new method to recognize which kind of extension Ruby did (for example, `tp.extension_type #=> :undef`)

Maybe we have no time to conclude this spec so I think it is difficult to introduce this feature (method_added) in Ruby 2.6.


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Feature #15287: New TracePoint events to support loading features
https://bugs.ruby-lang.org/issues/15287#change-75409

* Author: ko1 (Koichi Sasada)
* Status: Open
* Priority: Normal
* Assignee: ko1 (Koichi Sasada)
* Target version: 2.6
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# Abstract

I propose the following new TracePoint events:

* `loaded` (invoked after `require`/`load`)
* `method_added` (invoked after method definition)

# Background

Sometimes we need to hook loading iseq. For example, checking loading files and so on.
Also we want to know what kind of methods are defined.

For both purpose, we can use some hook methods such as `Module#method_added` and so on.
However, defining methods we can override this features.
So that if we have two tools/libraries using this feature, they can be conflicted.

# Proposal

Introduce new TracePoint events:

* `loaded` (invoked after `require`/`load`)
* `method_added` (invoked after method definition)

Also the following methods can be added:

* Active only `loaded` event:
  * `TracePoint#loaded_feature` returns feature name.
  * `TracePoint#loaded_iseq` returns `RubyVM::InstructionSequence` object (MRI only, internal feature)

# Optional proposal

Add `class_added` alias name for `class` event.




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