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Debugging with zero cost in production

php.internals

David Rodrigues

9 years ago

Hello, folks.

I'm thinking about a debug function to allow us to create "zero cost
declarations" in production code, as assert() does.

From what I understand, if I have something like assert(method()),
method() will not be called in production, only in development.

This behaviour is great because we can help the PHPUnit, for instance,
to capture messages in specific places to check if some process have
generated the correct value without test it alone.

For instance:

// On test()'ed method:
debug(TestStack::put($varValue));

// On test method:
test();
static::assertSame(123, TestStack::pop());

How it should be a debug code, should be important that it not be
generated and executed in production.

Could I use assert() to do that, in all case? Then I could consider it
as "already implemented".

Bye!

--
David Rodrigues

Fleshgrinder

9 years ago

On 10/24/2016 7:10 PM, David Rodrigues wrote:

> Hello, folks.
>
> I'm thinking about a debug function to allow us to create "zero cost
> declarations" in production code, as assert() does.
>
> From what I understand, if I have something like assert(method()),
> method() will not be called in production, only in development.
>
> This behaviour is great because we can help the PHPUnit, for instance,
> to capture messages in specific places to check if some process have
> generated the correct value without test it alone.
>
> For instance:
>
> // On test()'ed method:
> debug(TestStack::put($varValue));
>
> // On test method:
> test();
> static::assertSame(123, TestStack::pop());
>
> How it should be a debug code, should be important that it not be
> generated and executed in production.
>
> Could I use assert() to do that, in all case? Then I could consider it
> as "already implemented".
>
> Bye!
>

You can already use assert in exactly this manner.

--
Richard "Fleshgrinder" Fussenegger

Niklas Keller

9 years ago

2016-10-24 19:12 GMT+02:00 Fleshgrinder <php@fleshgrinder.com>:

> On 10/24/2016 7:10 PM, David Rodrigues wrote:
> > Hello, folks.
> >
> > I'm thinking about a debug function to allow us to create "zero cost
> > declarations" in production code, as assert() does.
> >
> > From what I understand, if I have something like assert(method()),
> > method() will not be called in production, only in development.
> >
> > This behaviour is great because we can help the PHPUnit, for instance,
> > to capture messages in specific places to check if some process have
> > generated the correct value without test it alone.
> >
> > For instance:
> >
> > // On test()'ed method:
> > debug(TestStack::put($varValue));
> >
> > // On test method:
> > test();
> > static::assertSame(123, TestStack::pop());
> >
> > How it should be a debug code, should be important that it not be
> > generated and executed in production.
> >
> > Could I use assert() to do that, in all case? Then I could consider it
> > as "already implemented".
> >
> > Bye!
> >
>
> You can already use assert in exactly this manner.
>
> --
> Richard "Fleshgrinder" Fussenegger
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
> You can use assert as long as you return a value that evaluates to true.

We use it in Aerys to have zero-cost debugging output:
https://github.com/amphp/aerys/blob/6335cc224e54999185119a28684804e91be458ae/lib/Server.php#L169

However, I think it would be nice to have a separate statement / function
that doesn't have that requirement. Then we could just use
`debug($this->logger->debug(...))` instead of
`assert($this->logDebug(...))` or `assert($this->logger->debug(...) ||
true);`.

Regards, Niklas