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Tagir Valeev
@tagir_valeev 5 years, 4 months ago 999 views

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Ever wondered how the JVM debugger 'Evaluate' feature works in IDEs? Long ago I thought that the Java debug interface (JDI) actually allows you to specify the expression and get back its value.

However, this is not quite possible: there's no Java language compiler inside the JVM. When the process is paused JDI allows you to read or write any variables and fields or even execute an existing method with given arguments. But nothing like addition or multiplication.

On the other hand, #IntelliJIDEA debugger allows you to evaluate even statements! You can write there `for`, `if`, `while`, `switch` - whatever. You can even declare local variables. So how this works?

The answer is simple: IDEA debugger has a built-in interpreter for Java! If you access an existing variable or a field, call a method or instantiate an object, it queries JDI. Otherwise, IDE itself does all the calculations.

The amusing thing is that debugger authors didn't bother to make it as strict as Java itself, so the language inside the interpreter is a much more permissive version of Java. For example, you don't need to initialize variables there! Default values like 0 are used automatically.

Of course, final variables could be changed. Why artificial limitations?

Another thing: most of the casts are not necessary. This interpreted Java more resembles dynamically typed languages like JavaScript. Duck-typing works: if there's a method, we can call it. Even if the highlighter complains.

Switch statements and expressions are more permissive there: you can switch over any type. Also, no default is necessary for switch expressions. If it's not visited, the evaluation will be successful.

In addition to use any type, you can use any expressions as case labels, not just constants! The first matching branch will be executed.

Finally, even if your project still uses Java 6 JDK, it doesn't stop you from using new language features. For example, 'var' declarations and patterns in instanceof work perfectly, because they are interpreted by IDE, not by your JDK. Just ignore error messages!

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Daniel Johnson
@DJohnson_CPA

Here’s a SPAC thread covering some basics for new followers. I will pin this to my profile if you want to share to anyone interested in SPACs.

SPAC timelines consist of these stages:
IPO – SPAC raises cash and begins trading as a unit. The cash is placed in Trust.
Searching phase – After IPO, the SPAC management team looks for a company to merge with. This is typically 24 months but can be shorter depending on the SPAC

LOI/Rumor – A letter of intent is announced publicly or Bloomberg/Reuters etc. breaks news of a rumor that a SPAC is close to a deal with a target.

The LOI/rumor stage does not always happen, most go straight to a definitive agreement. Rumors should only be considered to have value if from a trusted news source, internet rumblings are pure speculation. During this stage, a deal can still fall apart and not be signed.

Definitive agreement (DA) – deal officially inked. The SPAC begins filing paperwork with the SEC to have the merger approved to take the target company public. This process typically takes 4+ months after the DA is announced.

Kevin Roose
@kevinroose

On press call, Zuckerberg says FB users "naturally engage more with sensational content" that comes close to violating its rules. Compares it to cable TV and tabloids, and says, "This seems to be true regardless of where we set our policy lines."

Zuckerberg says FB is in the process of setting up a "new independent body" that users will be able to appeal content takedowns to. Sort of like the "Facebook Supreme Court" idea he previewed earlier this year.

Zuckerberg: "One of my biggest lessons from this year is that when you connect more than 2 billion people, you’re going to see the good and bad of humanity."

This is how Facebook says it's trying to change the engagement pattern on its services. https://t.co/3p0PGc912o

.@RebeccaJarvis asks Zuckerberg if anyone is going to lose their job over the revelations in the NYT story. He dodges, says that personnel issues aren't a public matter, and that employee performance is evaluated all the time.

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Simon DeDeo
@SimonDeDeo

So, today, for the first time in 25 (!) years of Apple, I downgraded. From the 2016 MacBook Pro to my 2013, which I had kept in a drawer...

It was pretty simple to do—Apple Time Machine backups let me do it with one click.

That first tweet captures, in two pictures, how badly Apple has “lost the plot” (to quote @wylieprof). On the right is the Apple MagSafe adapter, from 2013. On the left, what I had “upgraded” to.

Thanks, Apple! I really was nostalgic for worrying about yanking my computer off the table.

Oh and I really appreciated not knowing if my computer was charging. What was great was the little whoop sound you used, so that the speaker before me could be informed I was charging my laptop.

$\U0001f7e2 Ed Guiness$

🟢 Ed Guiness
@KiwiCoder

A long time ago I coded up a feature for SocialCoder which converts a link - any link - to a short URL. I use it all the time for sharing links to volunteer profiles and to volunteer opportunity listings.

The feature doesn't care what the link contains, it just hashes the URL, including any query params, and returns a shortened code.

More recently, around Christmas time, I added another feature where I can click a button to send a template notification to a charity that their new listing has been reviewed and published. I call it a next-steps email.

For the past few weeks, its all been working well. Its nice to keep automating things that previously were done by hand.

Fast forward to today.

A new opportunity listing is posted by a charity.

I review and publish it, tweet about it, then click a button to send the charity an emailed notification of next steps.

Lea Kissner
@LeaKissner

Last up in Privacy Tech for #enigma2021, @xchatty speaking about "IMPLEMENTING DIFFERENTIAL PRIVACY FOR THE 2020

Differential privacy was invented in 2006. Seems like a long time but it's not a long time since a fundamental scientific invention. It took longer than that between the invention of public key cryptography and even the first version of SSL.

But even in 2020, we still can't meet user expectations.
* Data users expect consistent data releases
* Some people call synthetic data "fake data" like
"fake news"
* It's not clear what "quality assurance" and "data exploration" means in a DP framework

We just did the 2020 US census
* required to collect it by the constitution
* but required to maintain privacy by law

But that's hard! What if there were 10 people on the block and all the same sex and age? If you posted something like that, then you would know what everyone's sex and age was on the block.

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Zach Weinersmith
@ZachWeiner

Hey, for people interested in this stuff, here's a thread about a change we made to running our facebook account:

So, about 5 years ago, we got on facebook. Why? Well, facebook has a big audience and they like to consume on facebook. So, we started posting comics there, even though we got paid nothing and facebook made money off the free content.

Why? Because back then, once in a while, you would say "also hey, I sell books" or "hey, I'm going to be signing at this event" and your facebook followers would actually see it.

Effectively, the implicit old arrangement was "facebook lets me reach readers efficiently, and I supply facebook with free content they run ads on."

Over time, like a bad business partner, facebook basically made it impossible to reach your audience without *paying them*. Thus, you supply them free content on which they run ads, and you get nothing in exchange.

$Peggy Klaver #FBR \U0001f30a\u270a\U0001f3fb\u270a\U0001f3fd\u270a\U0001f3ff\u270a\U0001f3fc$

Peggy Klaver #FBR 🌊✊🏻✊...
@Pegerella

The man who invented autocorrect should burn in hello.

It was meant to put a smile on your face. Please stop sending me instructions on how to turn my autocorrect off. 😳🤔

Texted my friends to ask if I could take their kids with me to Satan... still have not heard back from them. I meant Santa...

Thanks for all the love, I appreciate a follow. 💗

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Engineer Who
@Engr_Who

A long but must read thread. Udaybhan Rathore and myth making in Maratha history: An analysis. This is the thread on Udaybhan Rathore, who he was and how over the time period, his life was portrayed in maratha chronicles and pseudo history. (1/n)

Udaybhan rathore was the head of Bhinai thikana (84 villages) in Ajmer. He was the direct descendant of the famous Rao Chandrasen, Raja of Marwar (4th generation) who resisted Akbar all his life and never made any alliance with mughals like Maharana Pratap. (2/n)

Later in 1783, Maharaja of Jodhpur gave title of Raja to Bhinai family for their military service. Bhinai family and their direct descendant Raja Sh Mayuraj Singh still lives in Ajmer. Anyway coming to Udaybhan Rathore and story of Tanaji. (3/n)

Jai Singh's march on Shivaji and treaty of Purandar (1665) is a well known episode to repeat here. After getting the hill forts from Shivaji under the treaty, Jai Singh didn't have enough man-power to man every one of the small forts because of his next (4/n)

campaign against Bijapur. Jai Singh personally took over a couple of important forts like Kondhana (Sinhgarh), Purandar etc. Others were given to some mughals or their fortification walls destroyed. Jai Singh died in 1667 near Burhanpur while enroute to the north. (5/n)

Sheetal Rijhwani
@RijhwaniSheetal

How you can filter stocks for Intraday trades - 🧵

As a kid, we would do homework before school the next day - you have to do homework here too. A specific sector performs on a particular day and studying things a day before will help you spot that particular sector. (1/11)

To prepare for the next trading day, you got to check the Index charts of all sectors. You got to keep an eye on a specific Index if you see a few factors:

- If any Index closed exactly at the resistance, you can get a trade on either side on the next day. (2/11)

- If it gave a rejection candle at resistance.

- If any Index closed exactly at support, you can get a trade on either side the following day.

- If there was a bullish signal at the support.

- If any Index gave a breakout or breakdown and then gave a good closing. (3/11)

- If any Index has taken support at 50 or 200 EMA.

Once you spot the Index, look at all the stocks in that particular Index. Pick at least 3-4 stocks from that Index and add them to your watchlist for the next day. It's ideal to check both higher and lower timeframes. (4/11)

What you should do next day? (When I am unable to check Indices and stocks a day before, I sometimes directly start with this process.)

- Start with checking the top gainers/losers list. I observe market from 9:15 to 9:45am to check the sectors performing well on that day.(5/11)

Steve Stewart-Williams
@SteveStuWill

THREAD: 12 Things Everyone Should Know About IQ

1. IQ is one of the most heritable psychological traits – that is, individual differences in IQ are strongly associated with individual differences in genes (at least in fairly typical modern environments). https://t.co/3XxzW9bxLE

2. The heritability of IQ *increases* from childhood to adulthood. Meanwhile, the effect of the shared environment largely fades away. In other words, when it comes to IQ, nature becomes more important as we get older, nurture less. https://t.co/UqtS1lpw3n

3. IQ scores have been increasing for the last century or so, a phenomenon known as the Flynn effect. https://t.co/sCZvCst3hw (N ≈ 4 million)

(Note that the Flynn effect shows that IQ isn't 100% genetic; it doesn't show that it's 100% environmental.)

4. IQ predicts many important real world outcomes.

For example, though far from perfect, IQ is the single-best predictor of job performance we have – much better than Emotional Intelligence, the Big Five, Grit, etc. https://t.co/rKUgKDAAVx https://t.co/DWbVI8QSU3

5. Higher IQ is associated with a lower risk of death from most causes, including cardiovascular disease, respiratory disease, most forms of cancer, homicide, suicide, and accident. https://t.co/PJjGNyeQRA (N = 728,160)