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Date: Fri, 2 May 2025 15:51:59 +0300
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Subject: Re: [PHP-DEV] Deferred backtrace generation algorithm.
To: Rob Landers <rob@bottled.codes>
Cc: internals@lists.php.net
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From: edmond.ht@gmail.com (Edmond Dantes)

Hello, Rob!

> For what it is worth, the stack trace is not generated in the constructor=
 (at least from the perspective of the developer).

This is a design feature. In PHP, call frames for PHP functions are
stored in a separate stack. However, they are still stored following
the stack (LIFO) principle.

When a function returns a result, the memory of its frame will be
overwritten by the next one.
If the backtrace hasn=E2=80=99t been built while the stack still exists, th=
ere
might not be another chance.
That=E2=80=99s the main technical challenge.

For example, in Python (though this information might not be entirely
accurate), frames are objects that can be reused.

> Using reflection to create the exception without calling the constructor =
still results in the stack trace being generated in the exception object.

That's because PHP objects actually have two constructors:

* The internal constructor

* The PHP-land constructor, called __construct

The internal constructor must always be called.

-- Ed