Danack's comments

Danack | 8 years ago | on: Google Cloud Networking Incident

I can't comment as to multi-region, but we saw issues last night at around 6pm UTC, which look similar to the ongoing issues we are seeing.

Danack | 8 years ago | on: Google Cloud Networking Incident

We've been having 'fun' with ongoing issues for a site since 6pm UTC yesterday, which got dramatically worse this morning...and having been recurring during the day.

Having multiple hour outages makes me really want to go back to hiring a couple of physical servers in a rack somewhere.

Danack | 10 years ago | on: Remote code execution vulnerability in ImageMagick

"it offers significant improvements." - citation needed.

It was better for a period after the fork, but the only guy working on it hasn't maintained it that well...there's a significant number of bugs in GraphicsMagick that have been there for years.

Danack | 10 years ago | on: Why you should come to LambdaConf anyway

> It seems the most polite thing.

Nope, it's not polite, it's the most convenient thing for you.

> It’s certainly the most professional thing.

That phrase sucks. Whenever I hear it, I always interpret it as "Someone did something I didn't agree with, but I can't actually express a legitimate reason why they shouldn't do that."

e.g.

Programmer who never has any customer contact doesn't wear a suit to work - oh how unprofessional.

Someone has their job outsourced, can't be arsed to fly out to Bumfuck Nowhere to train the new people how to do his job - oh how unprofessional.

Customers of a conference object to giving their money to pay to listen to someone who thinks that a Monarchy would be better than Democracy, and that "Traditional sex roles are basically a good idea" - oh, how unprofessional of the customers!

If you have a legitimate reason to disapprove of someones actions you should be able to express it a lot more clearly than just calling them 'unprofessional'.

For the record - Moldbug/Yarvin wrote my favourite article on the internet: http://unqualified-reservations.blogspot.co.uk/2009/07/wolfr... But his lack of ability to see/predict the real world results of his actions, is totally consistent with his lack of ability to see the result of the policies he thinks we should be following.

And yes, people may be using their emotions to make a decision, rather than segmenting things perfectly and thinking about each of them separately with a coldly logical basis. Humans, eh?

Danack | 10 years ago | on: Read-only deploy keys

Yeah, it's terrible.

You can't give read only Oauth access to private repos....it has to be read/write. Which means if you want to use online CI tools with those private repos....you've got to hope they don't either turn malicious, or they get hacked and have their keys copied.

Danack | 10 years ago | on: Banks have never heard of SYN/ACK

From the fine article:

  1. Customer places an order.
  2. SYN: Can I charge $30?
  3. SYN/ACK: Yes.
  4. ACK + SYN: Do it.
  5. SYN/ACK: I am gonna do it.
  6. ACK: I see that you're gonna do it.
  
"If that was their model, then at no point does a communication failure cause a charge to be in an ambiguous state. If I never get the message in #5, the customer is not charged. If I get the message in #5 and my response in #6 is not received, the customer is not charged."

Er.....that doesn't appear to solve anything, instead it just pushes the error state down a level; there's still an ambiguous state where #6 is sent and not received.

The client thinks the charge is going to take place, and so thinks the client will be charged, but the bank never gets #6 and so never makes the charge, aka distributed atomic operations are hard.

Danack | 10 years ago | on: GitUp makes Git painless

The slowness appears to be caused by continual directory scanning. For me at least, turning off the "Refresh when files change" option, and so having to do "view, refresh" or Command-R, made SourceTree be zippy again.

And as I'm usually on a laptop, having less continued CPU usage is a good tradeoff against having to press refresh when I'm going to do something in SourceTree.

Danack | 11 years ago | on: Korean Shipbuilder Uses Exosuit to Help Build World's Largest Freighter

Also people are probably used to holding things that don't matter too much if dropped. If someone dropped a 10/20/30 kg bag of rice and it landed on my toes, the bag would just fold around the foot and it wouldn't be a problem.

If someone dropped a 30kg piece of steel and it landed corner first, there's a decent chance of it just going straight through the foot.

Danack | 11 years ago | on: Dependency Injection, Inversion of Control and the Dependency Inversion Principle

>> There is a second form of Dependency Injection that uses setters instead of constructor injection. Do not use this form. >Why?

Not using setter injection eliminates a huge class of bugs that occur when people try to use objects that haven't had all of their dependencies injected yet:

    $user = new RegisteredUser();
    // Any code that touches $user here will be bad
    $user->setEmail($email);
> constructor injection can become a nightmare.

Which is why people use library to do it for them - an example for PHP https://github.com/rdlowrey/auryn.

Danack | 11 years ago | on: Things you should know about PHP 7

> function add( ... ): float {}

Which if you read it out, it sounds entirely natural "This is a function called foo, which takes some params, and returns a float". Most of the other variants don't read as naturally.

> Since that's how it's done in other languages and people would feel at home with it.

PHP doesn't need to copy the mistakes of other languages. It's got plenty of its own mistakes.

Danack | 11 years ago | on: PHP7 Gains Scalar Type Hints

> Is there any other benefit?

Strict types make it easier to reason about code, that the tl;dr version.

> To me it seems that Ze'ev's proposal would be even better for you - > it does the equivalent of the validation and conversion automatically > including with an error if it doesn't validate.

Rather than having int 'types' which we can reason about, it has int 'values' which are harder to reason about. Types can be reasoned about just by looking at the code. Values can only be reasoned about when running code. A contrived example:

    function foo(int $bar){...}

    foo(36/$value);
In strict mode, this would be reported as an error by code analysis.

For the coercive scalar type proposal, this code works - except when it doesn't. This code works when $value = 1, 2, 3, 4 and breaks when $value = 5.

This is the fundamental difference; whether conversions between types have to be explicitly done by code, and so any implicit or incorrect conversion can be detected by static code analysis tools, or whether the conversions are done at run time, and so cannot be analyzed fully.

This means most of these errors will be discovered by users on the production servers. Strict mode allows you to eliminate these types of errors.

Yes, this means I need to add a bit of code to do the explicit conversion, but I just don't convert between values that much. Once a value is loaded from a users request, config file or wherever, it is converted once into the type it needs to be. After that, any further change in type is far more likely to be me making a mistake, rather than an actual need to change the type.

> Any idea why it was rejected so badly? Is it because the coercion rules are different from the rest of PHP?

At least in part it was because the RFC was seen as a way to block strict types; about half of the RFC text is shitting on people desires for strict types, which did not make people who want strict types be very receptive. If it had been brought up 6 months ago, there is a good chance it would have passed, or at least would have been closer.

Some parts of the proposal were good - other parts were nuts that were pretty obvious the result of the RFC only being created once the dual mode RFC was announced and about to be put to the vote, with a very high chance of passing.

* Good - "7 dogs" not longer being converted to "7" if someone tries to use it as an int.

* Bad - Different mode for internal function vs userland functions e.g. "Unlike user-land scalar type hints, internal functions will accept nulls as valid scalars." and other small differences. This is even more nuts than you might realise as it means if you extend an internal class, and overload some of the methods on the class, those methods will behave differently to the non-overloaded methods.

* Bad - Subtle and hard to fix BC breaks in conversion which are probably not right anyway. e.g. false -> int # No more conversion from bool true -> string # No more conversion from bool

It is a shame that the discussion became so contentious. It would have been good if the conversion rules could have been tidied up, but all the time and energy had been used up the not particularly productive discussion.

Danack | 11 years ago | on: PHP7 Gains Scalar Type Hints

> Can you explain why?

Hopefully.

> How does putting (int) before the arguments to function help anything?

It wouldn't. Anyone who is casting from an unknown type to an int by using just `(int)` is doing something wrong in my opinion.

Even in web-based applications there are at least two layers of code: i) One where the type of the values are unknown and they are represented as strings. ii) One where the types of the values are known.

At the boundary between these two layers you should have code that inspects the strings that represent the input values, check that they are acceptable, and convert them to the desired type. If the input values cannot be converted to the desired type, the code needs to give an error that is both specific to the type of error so that a computer can understand it, as well as provide a human understandable explanation of why the conversion was not allowed.

The reason why I want strong types is that I never, ever want to blindly cast from one type to another. The decision about how to convert from one type to another, should always be made at a boundary between areas of the application where types are known, and the areas where the types are unknown. I always want to be forced to make that decision in the right place, using code that gives useful errors and messages, rather than having the value coerced into the desired type.

tl;dr I won't use (int) to cast, I will use something like the code below.

cheers Dan

    function validateOrderAmount($value) : int {
        $count = preg_match("/[^0-9]*/", $value);
        
        if ($count) {
            throw new InvalidOrderAmount("Order amount must contain only digits.");
        }

        $value = intval($value);

        if ($value < 1) {
            throw new InvalidOrderAmount("Order amount must be one or more.");
        }
        
        if ($value >= MAX_ORDER_AMOUNT) {
            throw new InvalidOrderAmount("You can only order ".MAX_ORDER_AMOUNT." at a time.");
        }
        
        return $value;
    }

    function processOrderRequest() {
        $orderAmount = validateOrderAmount($_REQUEST['orderAmount']);
    
        //Yay, our IDE/static code analyzer can tell that $amount is an int if the code reached here.
        placeOrder($orderAmount);
    }

Danack | 11 years ago | on: PHP7 Gains Scalar Type Hints

This is actually quite revealing. Some people think that PHP is just used for the same small web pages it was used for 15 years ago.

Other people would like to use PHP more as a general computing language.

Having optional types takes nothing away from using PHP for simple web pages, but does make it easier to right analyzably correct programs.

The fact that the founder of a language doesn't want to see it grow is quite depressing.

Danack | 11 years ago | on: PHP7 Gains Scalar Type Hints

PHP has had type-hints for parameters for several version, but they could only be used for classes. The new types-hints cover the 'scalar' values (aka not object) and are int, float, string and bool. They allow a function to declare what they types of the variables it receives should be like:

function foo(int $x) { // x is guaranteed to be an int. }

The type-hinting for scalars has two modes:

* strict - the parameter passed to the function must be of the exact* type. * weak - the parameter passed to the function will be converted to the correct type.

The strictness depends on what mode PHP was in when the function was called. This is the right choice as it:

* Allows library authors to write their code in either strict or weak mode.

* End-users to write their code in either strict or weak mode. Or even without using scalar type-hints.

* End-user to be able to choose when they are writing their code do they want their variables to be converted to the type expected by the library automatically, or do they want PHP to give them an error if they accidentally pass the wrong type of variable to a function that is expecting an int.

*except for some widening rules, e.g. you can pass an int where a float is expected, as ints can be converted into float without data loss (for ints less than 2^53).

Danack | 11 years ago | on: PHP7 Gains Scalar Type Hints

>The PHP 5 to 7 jump should be much smaller than from 4 to 5.

And also the jump from 5.4+ to 7 is probably smaller than the jump from 5.2 to 5.3.

Although I think the PHP project does need to support versions for longer, the adoption rate of 7 is going to be quite rapid due to the low barrier of doing it, and the massive performance and language gains.

Danack | 11 years ago | on: PHP7 Gains Scalar Type Hints

To explain the slightly horrible fact that there are two modes, strict and weak with strict mode being enabled on a per file basis; people just couldn't agree on whether the types should be strict or if they should use PHP's existing coercion rules. (Or even a 3rd new set of conversion rules, but lets ignore them).

Having an optional mode per file allows:

People who want to write code with strict types can do so. People who want to write code with weak types can do so. People who want to write code without these new fangled types can continue to do so.

All without any issues of compatibility between running code on the current version of PHP and what will be the next one, and without any compatibility issues for libraries that are solely written in one mode, being used in applications that are written in the other mode.

\o/

To be honest, I'm completely in the strict camp - but it's awesome that we've gotten a solution that should allow everyone to use the mode they want, without splitting the PHP ecosystem.

Danack | 11 years ago | on: My Love-Hate Relationship with Stack Overflow

"Are there any [lang] libraries that are backings for the [service] API?"

This is explicitly listed as off-topic:

Questions asking us to recommend or find a book, tool, "software library, tutorial or other off-site resource are off-topic for Stack Overflow as they tend to attract opinionated answers and spam. Instead, describe the problem and what has been done so far to solve it."

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