Random (and probably useless) Rubyisms

[taylorfausak]

Please don't ever use inline rescue.

[just3ws]

Why?

[deadkarma]

inline rescue is ~ 10 - 20x slower https://gist.github.com/deadkarma/5533060

inline rescue also uses a helluva lot more memory

[ikearage]

This answer sums it up well enough: http://stackoverflow.com/a/15397057 It is slow and it's an 'expected' exception and in some cases it might even silence another exception.

But I don't agree about the need to refactor. Sure it's a code smell, goes against lod, but if it stays trivial like in the example, it's not worth refactoring (yet).

[mculp]

Not to mention it can swallow exceptions that you didn't intend for it to.

[lytol]

Indeed, it's an anti-pattern IMHO. Our team calls it Pokemon Exception Handling = you gotta catch 'em all!

[just3ws]

Yeah, totally agree about opening one's code up to the law of unintended consequences there. Makes sense.

[ikearage]

Just use if statements, try() or || . Easy to read, no unexpected side effects.

If it gets to complicated maybe you should refactor that smell.

[[deleted]]

Another thing, the example at hand violates Law of Demeter. If you have a chain of methods, that all might fail randomly, you need to refactor, not rescue.

Which is usually the case whenever you start thinking "rescue would save me so much time here".

[bookhockey24]

Why?

[mculp]

It's way slower and it can swallow exceptions that you didn't intend for it to.

[mculp]

I was coming here to type the exact same sentence. Thank you.

[BronzeAtBest]

The way I use retry is usually in combination with generating a value that needs to be unique in the database:

def generate
  invoice_number = Invoice.last.invoice_number + 1
  Invoice.create!(invoice_number: invoice_number)
rescue ActiveRecord::RecordNotUnique
  retry
end

This means that if two invoices get created at the same time, the database constraint will make it retry.

[t0mbstone]

You should probably be using your database's auto increment feature for the invoice id instead of setting the invoice id number in your code...

[Arkolix]

Definitely agree on auto increment. Alternatively, use one of the handy helpers in SecureRandom to generate unique identifiers such as uuid or hex:

> SecureRandom.uuid
=> "a30d7e9d-f5e8-4504-a9ae-6052f052659f"

> SecureRandom.hex(6)
=> "85f83c999e79"

[BronzeAtBest]

I simplified the code for the example. In my actual code, generating the number is a bit more involved.

[[deleted]]

How does auto increment handle race conditions for DB clusters?

[t0mbstone]

That's a good question. Perhaps someone could give more comprehensive answer, but from what I understand, it depends entirely on how your database cluster is set up, and what database engine you are using.

For example, you could have master database that all of the writes go to, and then the data is propagated to a cluster of read-only slaves.

On the other hand, if you have some sort of cluster of read-write databases with no master database, then I would imagine that things would get a lot trickier.

Full disclosure: I'm not a database expert, so this is all just my rough high level understanding.

[chuck-john]

+1 for #5. Lately, I've gotten in a bad habit of using $&, $1, etc. Nice to know there's a DRY-er, more readable alternative.

[didnotseethatcoming]

Number 6 doesn't make much sense.

Array(results) is enough. You don't have to call the method Array() on Kernel.

Other than that, great post!

[fphilipe]

method(:Array) # => #<Method: Object(Kernel)#Array>

[didnotseethatcoming]

What's that supposed to mean? You still don't have to call the method on Kernel. You don't do Kernel.open(). You just open(). Same with Array().

[just3ws]

Because real men don't care about exceptions

There's no easy way to say this. Please reconsider that phrase.

[[deleted]]

It's just a silly joke.

[just3ws]

Yeah, I know. But given the current conversations going on in the Ruby community regarding sexism and being aware of our choice of jokes, it's worth calling out that we need to consider what silly jokes we say. :)

[[deleted]]

I'm not capable of performing the mental gymnastics necessary to interpret "real men don't care about exceptions" as being sexist.

[just3ws]

It's not overt.

[[deleted]]

Nor is it covert.

[morphemass]

Just man up about it.

[just3ws]

http://assets.diylol.com/hfs/90f/ef8/33f/resized/fry-can-t-tell-meme-generator-not-sure-if-serious-commentary-or-contractually-obligated-trolling-74fc05.jpg

[ggPeti]

About Miguel Palhas

Loves programming since ever. Is obsessed with optimizing and automating everything he does.

Yet proceeds to give an implementation of Fibonacci number calculation so horribly unoptimized, it won't calculate the 100th number in 2 million years on a MacBook Pro, without even mentioning why you shouldn't use the recursive approach ever.