Michael is...

How to use new C/C++ preprocessor features in Visual Studio (e.g. __VA_OPT__)

Wed, 20 Oct 2021 00:00:00 GMT

I once again experienced the pain of working with C++ variadic macros in Visual Studio. This particular issue was wanting to insert a comma in my macro output after the __VA_ARGS__, but only when variable args are passed. I found a solution in the new C++20 preprocessor API and thought I'd share how it works and how to enable it.

My example macro looks like this:

// Custom error logger that lets a caller supply an error message
// with a printf format and variable args. I want the user message to
// come first and then some OS specific error details.
#define LogOSError(CODE, USER_MSG, ...) { \
    Log(USER_MSG " code: 0x%x, os: %s", __VA_ARGS__, CODE, OSMessage(code)); \
}

LogOSError(123, "Failed to write file.");
// Preprocessor output:
Log("Failed to write file." " code: 0x%x, os: %s", , 123, OSMessage(123));
// The above code won't compile because there's an extra comma where the __VA_ARGS__ is used.

LogOSError(123, "Failed to write file '%s'.", "secrets.txt");
// Preprocessor output:
Log("Failed to write file '%s'." " code: 0x%x, os: %s", "secrets.txt", 123, OSMessage(123));
// This compiles because we have a populated __VA_ARGS__.

// How do we make this work for both cases???

We can make both cases work by using the new __VA_OPT__ preprocessor identifier that's included in the C++20 standard. It's usage looks like this: __VA_OPT__(X), where X will be inserted when __VA_ARGS__ is populated. All we need to do is replace X with a comma character!

My macro now looks like this:

// Include a comma iff we're given a populated __VA_ARGS__.
#define LogOSError(CODE, USER_MSG, ...) { \
    Log(USER_MSG " code: 0x%x, os: %s", __VA_ARGS__ __VA_OPT__(,) CODE, OSMessage(code)); \
}

It turns out that support for this and other new preprocessor things were added to MSVC starting in Visual Studio 2019 v16.5. It's sad that it took until 2021 to get this feature, but whatever, that's the state of software for you.

The Microsoft docs state that you only need to pass the -Zc:preprocessor compiler option to enable the new features, however that wasn't the case for me on Visual Studio 2019 v16.11.13. I also needed to set the C++20 standard mode option -std:c++20. Without the mode you'll see errors saying the __VA_OPT__ identifier doesn't exist. And conversly, setting only the standard mode will result in your __VA_OPT__(X) identifiers being replaced with (X).

Here are the new options I'm passing to cl.exe

-std:c++20 -permissive -Zc:preprocessor -wd5105

The -permissive option ignores all of the warnings about my existing code not adhering to the C++ standard. The disabled 5105 warning is to suppress the macro expansion having undefined behaviour message coming out of the Windows 10 SDK...sigh.

I use the compiler driver directly from a script, so if you're compiling from within Visual Studio then you're on your own. Just look for relevant GUI labels.

That's it! See the full list of changes in v16.5 for more details. And if you enjoy writing macros or seeing the crazy shit people come up with in order to have basic metaprogramming then check out this post on recursive macros with __VA_OPT__.

Recipe: Red Curry with Shrimp

Wed, 13 Mar 2019 12:00:00 GMT

Spring in Vancouver, 2018. I know it has nothing to do with curry, I'm just tired of winter here in Toronto.

I made a red curry with shrimp for the second time, making sure to incorporate modifications from the first attempt. It was so good that I knew I had to save it here for future me and for anyone else that enjoys cooking or eating Thai food.

I'll start by sharing a picture of the finished meal. Unfortunately, I didn't think to take one until I already started eating so it lacks that picturesque composition with the unadulterated garnishes resting on top.

Servings: 4 hungry adult portions.

Cook time: The curry takes roughly 20 minutes to cook. The homemade shrimp stock takes 45 minutes to cook. You'll have to factor in prep time based on your past cooking experiences.

Shrimp Stock

The most flavourful stock is created from shelled shrimp. If you can't find that then you can use deshelled shrimp tails. It's less flavour though, so you'll likely want to make less stock. I've included both options below.

Shelled Shrimp:

Yields ~12 cups of stock
1 lbs (~8 cups) shrimp shells
16 cups water
1 tsp black peppercorns (ground pepper is fine)
2 tsp salt

Deshelled Shrimp:

Yields ~4 cups of stock.
1 lbs (~8 cups) shrimp; remove the tails and set aside 1.5 cups of shrimp for the curry
4.5 cups of water
0.5 tsp black peppercorns (ground pepper is fine)
0.5 tsp salt

Other ingredients:

1 cup yellow onions, coarsely chopped
1/2 cup celery, coarsely chopped
1/2 cup carrots, coarsely chopped
3 garlic cloves, smashed
2-3 bay leaves
1 tsp dried thyme

Collect the shells or tails if you don't have shelled shrimp, and rinse under cold water.
Add all ingredients to an appropriately sized pot and bring to a boil.
Reduce heat to a simmer. Partially cover. Cook for 45 mins.
Periodically skim off any foam that builds on the surface. It'll likely be brownish-grey in color.
Once done, strain the contents into a bowl/container, completely cool it immediately via an ice bath.
You can store the stock in the fridge for three days or freeze for two months. Set aside for now.

Curry

1.5 tbsp olive oil
1.5 cups shrimp stock
1/4 - 1/2 lbs raw shrimp
1 large yellow onion, sliced or diced
3-5 garlic cloves, minced
2 tsp galangal, minced/grated (can substitute with regular ginger)
1 red pepper, thinly sliced and de-seeded
4-8+ mushrooms of your choosing, chopped
1 (400 mL or 13.5 oz) can of regular or light coconut milk (I use the regular Thai Kitchen brand)
3 tbsp red curry paste - it'll be a bit spicy so use less if you want a milder curry (I used premade paste from AROY-D and I'm sure a homemade paste would be even better!)
2 tsp fresh lemongrass, finely minced (just shy of 1 stock; it's OK to add the entire stock)
2 tbsp palm sugar (can substitute with brown sugar, and/or add more sugar to sweeten the curry)
5 kaffir lime leaves (can substitute with lime juice; not sure how much to use so you'll have to experiment)
1 tbsp fish sauce
salt n' peppa
Handful of fresh Thai basil leaves
Rice or rice noodles

Other ideas to try: carrots, sweet potato, snap peas, broccoli. You can also substitute the shrimp stock with chicken stock and the shrimp with chicken or tofu.

Garnish

Red chili pepper, diced
Green onions, thinly sliced
Fresh cilantro, chopped
Lime wedges

Start prepping ingredients while the stock is boiling. You may also want to get your rice going now depending on how long that takes to cook. Keep in mind that the curry takes around 20 minutes. When the stock is cooled proceed with the next steps.
In a large bowl whisk shrimp stock, 13.5 oz coconut milk, and 2 tsp lemongrass until the coconut milk clumps are gone. Set aside.
Heat 1.5 tbsp olive oil in a medium/large soup pot or a deep sauce pan on medium heat. Once hot, cook 1 large onion, 3-5 garlic, 2tsp galangal/ginger and a little salt for about 5 minutes or until the onions start to become translucent. Periodically stir so that the contents don't burn.
Stir in 3 tbsp curry paste and cook for 2 mins, frequently stirring. Use a wooden spoon or spatula to smush the curry so that it evenly cooks.
Stir in the stock & coconut mixture from step 1. Bring to a boil.
Add 1 red pepper, 4-8+ mushrooms, 1/4 - 1/2 lbs shrimp and 3 of 5 kaffir lime leaves (or substitute lime juice). Cook until the shrimp turns pink, about 2-4 minutes.
Add 1 tbsp fish sauce, 2 tbsp palm/brown sugar, and season with salt & pepper to your liking. Stir and remove from heat.
Tear basil into halves if the pieces are large. Add to curry along with the remaining 2 lime leaves.
Cover the pot and let it rest for 5-10 minutes to let the flavours develop.
Serve the curry with rice or noodles and garnish with cilantro, green onions and chili if you like it extra spicy. Optionally squeeze a lime over the bowl, although I didn't bother because the lime leaves were sufficiently zesty.
Eat it.

I hope you enjoy this curry! Leave a comment if you give it a try and tell me how it was.

How to Fix a Honeywell VC Series HVAC System with a Broken Actuator (VC8111-11)

Sat, 09 Feb 2019 12:00:00 GMT

It's really, really cold in Toronto, Canada right now. Bad timing for a broken heater!

Recently my Honeywell HVAC fan coil unit stopped outputting heat and instead produced a loud and repetitive banging noise. This is not the first time it happened and paying for a repair is not cheap, so I decided to figure it out myself and save hundreds of dollars. I'll teach you how to do the same repair.

When I say you'll save hundreds, I literally mean that. I was quoted $316 CAD for a 5-minute job! The cost to do this myself was $69.38 CAD which is the price of a new actuator.

Anyway, having gone through this before, I knew that the banging sound meant the actuator was broken or nearing its death. To confirm this I opened the HVAC access panel and saw the actuator's tab moving up and down over and over. The bang is probably caused by the pressurized water flowing into the valve, which is partially opening and closing.

I'm going to walk you through the steps to fix this because I did extensive searching and wasn't able to find any tutorials on the web or any videos on YouTube for this specific setup. I'm working with a Honeywell VC Series with a 2-position hydronic valve. The actuator is a VC8111-11. These steps should apply to any VC2, VC4, VC60 or VC8 series 2-position actuators, but your mileage may vary. Consult this Honeywell actuator manual (archived link) and verify that your actuator is in the first table. If it's not then this guide may not be applicable. It's probably a good idea to read over the manual before proceeding, but don't get discouraged if anything is confusing because I'll walk you through the steps.

!!! WARNING !!!

Proceed at your own risk. I'm not a professional so don't hold me accountable if you follow this tutorial and end up breaking something. All I can do is share what worked for me. If you're uncomfortable doing this then call a technician and pay for some peace of mind.

Diagnosing the Problem

Confirm that your actuator is in a stuck position by opening the fan coil panel and observing the actuator when your system is set to running state, i.e. it should be blowing out hot/cold air. Don't touch anything, just observe. If it's moving up and down and producing a sound then chances are you can fix it following this guide. If the actuator doesn't move when your heat/AC is active, or you notice water leaks from the valve then it may be the VC valve cartridge that needs replacing (or some other issue). You should NOT attempt to repair the valve yourself since it may require draining, venting, soldering, etc. If in doubt at all, call a professional.

If you happen to have two HVAC systems in your home and both use identical components then you can do an experiment to see if the actuator is truly broken. Only do this if you're comfortable with disconnecting a working system. Follow the guide below and remove both the broken and working actuators. Now install the working actuator to where the broken one was. Turn on the unit and see if you get your hot/cold air. If not then the problem may be your valve cartridge or some other component. You can also try re-installing the supposedly broken actuator and see if that fixes things. I was able to get another two weeks of life out of mine just by resetting it.

Buying a Replacement

If you determine that the actuator is broken then note down its model number. You'll need to buy a replacement with the exact same specifications. The actuator I replaced was a VC8111-02, which seems to be a discontinued model. However, the VC8111-11 has the exact same specs so I bought that instead. On the side of the actuator you'll see a label for wiring. It will say either SPST or SPDT. Make sure your replacement has the same type. I got my actuator from https://www.build.ca/HONVC8111ZZ11 for $61.40 CAD before tax (as of Feb 2019). It took two days to ship with free shipping.

Here's a picture of the part I was replacing:

Here's the side label showing that it's an SPST type:

And here is the new part:

Removing the Actuator

!!! WARNING !!!

Turn off power to the fan coil system by opening your home's circuit breaker box, finding the HVAC system and flipping the breaker to the off position. This is so important that I cannot stress it enough.

IF YOU LEAVE THE POWER ON THEN YOU CAN DIE OR SERIOUSLY INJURE YOURSELF DURING THIS REPAIR.

These are the only tools I needed for the repair:

With the power turned off, you'll start by disconnecting the actuator's power line. You should have a power panel of some type near the valve. This houses the HVAC electronics. Mine looks like this without the cover:

Open up your panel and then follow the power cable coming out of the actuator. You're going to be disconnecting those wires, but first, you need to note down the order of the colours. Mine goes blue, black, tan. Write down your order because you'll need to install the new wires the exact same way. Here's a picture of mine with the wires still connected:

My wires are fed into some type of socket with three screws that clamp down to hold them in place. If you have the same thing then use a screwdriver to loosen the holds and then gently remove the wires. Here's mine with the wires disconnected:

Now you can disconnect the actuator from the valve. There's a small grey button on the bottom of the actuator. You can see it in this photo:

You want to press and hold that, then turn the actuator counter-clockwise to unlatch it from the valve. It should lift off after a 45-degree turn. It's possible that you'll need to turn clockwise on your setup. Here's a video of me disconnecting my actuator:

This is what my setup looks like with the actuator removed (note that the spring looking piece extending out of the valve is the VC valve cartridge:

Here is a photo showing the old and new actuator. The broken one has been through a lot over the years...

Installing the Actuator

Connecting the actuator is just as simple as removing it. First, align the bottom tab with the valve stem (i.e. the exact same spot you lifted off the actuator); apply slight downward pressure on the actuator body; turn the opposite way from the removal step. It should automatically latch on after a 45-degree turn. Here's a video of me connecting my new actuator:

The last step is to install the power cable. Inspect the wires from the new actuator and compare the exposed wire length to the broken actuator. You want the exposed tips to be the same length. Mine was too long out-of-the-box so I trimmed them with wire cutters. You can probably snip them with scissors too.

Feed the cable into the power panel. You may have to bend the cable a bit to make it fit. If you have the same connector setup as I do then leave just enough slack so that the wires can slide into the socket without tension or a bending pressure. Tighten the screws to clamp down on the wires. Double-check that you have the wires in the same order as before!!! Also, try to keep the actuator cable from resting on the water pipe since it can get really hot and may melt the wire.

The finished install should look something like this:

Final Step: Testing the System

Go to your unit's thermostat and make sure it's in the off position. Now with the HVAC system left exposed, return to your home's circuit breaker box and turn the fan coil power back on. MAKE SURE NO ONE TOUCHES THE FAN COIL UNIT WHILE POWER IS ON!. It might be smart to have someone else flip the circuit for you so that you can watch the unit for trouble. With the power back on, verify that nothing is on fire or doing anything obviously bad. If something seems wrong then kill the power via the circuit breaker and call a technician.

Now turn on the thermostat and set it to a temperature above/below the current temp. If you're running heat then go above, otherwise go below for A/C. This should activate the actuator and you'll see the white tab move into position. Mine travels fully down and opens the water line. If nothing happens then you may have a faulty unit or your wiring is incorrect. If it activates and your unit produces heat/cold air then you're done! The last thing to do is to kill the power again, put the cover back on the power panel, and cover up the unit's access panel.

Here a video of my HVAC being powered up:

Conclusion

That wasn't so hard, eh? Hopefully you didn't run into any trouble along the way. Now if you ever hear that horrible banging noise again then you'll know what to do...unless the sound is coming from a demon that's possessed your HVAC, in which case you should probably just move.

I want to end this by saying that I have nothing against professional HVAC technicians. They spend years studying this stuff and deserve to make a living. My only gripe is being charged a ridiculous sum for what boils down to a 5-minute replacement of a $70 part that has a seemingly short shelf life. If I didn't go into this knowing that I needed a new actuator then I would have hired a technician.

Favourite Quotes Found in 2018

Tue, 01 Jan 2019 22:40:32 GMT

Here are all the memorable quotes that I discovered in 2018. I keep track of these by stashing them in a Telegram "Quotes" channel. That makes it really easy to capture a great quote when my phone is nearby. Going into 2019 I want to read over my growing collection more often than I currently do.

Some grumpy penguins at the Osaka aquarium.

The Philosophers

I come across a lot of stand-out quotes from philosophers, especially the Stoics. Here are a few that stuck out for me this year:

“The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane.”

Marcus Aurelius

“This is the real secret to life—to be completely engaged with what you are doing in the here and now. And instead of calling it work, realize it is play.”

Alan Watts

“Nothing truly stops you. Nothing truly holds you back. For your own will is always within your control. Sickness may challenge your body. But are you merely your body? Lameness may impede your legs. But you are not merely your legs. Your will is bigger than your legs. Your will needn't be affected by an incident unless you let it.”

Epictetus

“Anything in any way beautiful derives its beauty from itself and asks nothing beyond itself. Praise is no part of it, for nothing is made worse or better by praise.”

Marcus Aurelius

“What can be presented without evidence can be dismissed without evidence.”

Christopher Hitchens

Artists and Thinkers

“Instead of asking yourself, 'what do I want to do?', ask rather, 'who do I want to be?'. Whatever you're doing for work, whatever, throw yourself into it wholeheartedly, even if you realize it's just a transitional gig while you search for something better. Don't ever worry that you'll be doing this for the rest of your life. You won't.”

Adam Robinson

“Unrelenting enthusiasm. In all matters, be enthusiastic. Others will want to be around you, including work with you and you'll flourish. Unrelenting enthusiasm.”

Adam Robinson

“If you're not getting the results you want, change what you're doing.”

“If you cannot write well, you cannot think well; if you cannot think well, others will do your thinking for you.”

Oscar Wilde

“Sure I love surfing and throwing massive ragers, but I also like reading about quantum dynamics.”

Surfer Campo, Masters in Quantum Engineering (a friend of Chad)

“If you imagine less, less will be what you undoubtedly deserve. Do what you love, and don’t stop until you get what you love. Work as hard as you can, imagine immensities, don’t compromise, and don’t waste time. Start now. Not 20 years from now, not two weeks from now. Now.”

Debbie Millman

“Stay away from negative people. They have a problem for every solution.”

Albert Einstein

“...and basically what I did is I grabbed some of our assets. Of course you can't preview them because Windows bitmap viewer doesn't actually work, even though they invented the format.”

Casey Muratori (HMH Day 58)

“I much prefer the sharpest criticism of a single intelligent man to the thoughtless approval of the masses.”

Johannes Kepler

“Easy choices, hard life. Hard choices, easy life.”

Jerzy Gregorek

“I am an old man and I have known a great many troubles, but most of them never happened.”

Mark Twain

“It's all so meaningless, we may as well be extraordinary.”

Francis Bacon

Monks

This is the only monk quote I have. Maybe I'll find more in 2019.

“Often, when we say, "I love you" we focus mostly on the idea of the "I" who is doing the loving and less on the quality of the love that’s being offered. This is because we are caught by the idea of self. We think we have a self. But there is no such thing as an individual separate self. A flower is made only of non-flower elements, such as chlorophyll, sunlight, and water. If we were to remove all the non-flower elements from the flower, there would be no flower left. A flower cannot be by herself alone. A flower can only inter-be with all of us… Humans are like this too. We can’t exist by ourselves alone. We can only inter-be. I am made only of non-me elements, such as the Earth, the sun, parents, and ancestors. In a relationship, if you can see the nature of interbeing between you and the other person, you can see that his suffering is your own suffering, and your happiness is his own happiness. With this way of seeing, you speak and act differently. This in itself can relieve so much suffering.”

Thich Nhat Hanh

Producing Ideas

Mon, 08 Jul 2013 16:50:00 GMT

Galleria Borghese in Rome, Italy.

Need to come up with a killer app idea that nets you billions? Dying to discover that one missing ingredient in the cure for male pattern baldness? Writing a guaranteed blockbuster screenplay but you have no idea what it will be about? Well good thing you found this post because I'm going to teach you how to come up with endless ideas. There will be so many ideas coming out of you that you'll be thinking your sushi dinner gave you food poisoning.

Now keep in mind that I didn't make these steps up myself. I'm not an idea scientist. These steps are from a short book on generating ideas. It was an interesting read because I never saw ideation as a process that can be deliberately practiced.

You'll just have to take my word that these steps work, until you try them for yourself. If they don't work, I'll give you back your wasted time. No questions asked. Just send me a letter with paid return postage and I'll ship back a parcel of time. Sound fair? Alright, we now embark down the trail of learnings and such...

Step 1

Gather raw materials for your mind.

There are two kinds of material: specific and general. This first step is all about researching the problem at hand. You must only focus on gathering material at this stage.

Try to find specific facts that relate to the immediate problem at hand. For example, if you are trying to market a product, you would learn everything you can about the product and the people that use it.

In regards to general material, this is something that we collect all the time. Sources include books, browsing the net, talking to people, hearing stories, travelling, etc. This type of general knowledge provides a constant enrichment. Think of it as a large catalogue of interesting facts and experiences that you can pull from. The more you grow this, the easier it will be to synthesize new ideas.

Step 2

Work the material over in your mind.

Allow it to penetrate deep into your thoughts. Take one fact and manipulate it. View it from different angles and get a feel for its meaning. Now take another fact and see how it fits with the other. Your goal is to find relationships. New combinations will be synthesized when facts begin to combine. You may come up with seemingly good ideas during this step. It is possible to have a brilliant breakthrough, but it's not likely. Take your small ideas and write them down. Use them as extra material for this process.

Don't rush this stage. It can very tedious and tiring, but it cannot be skipped. When you feel like you are running out of energy, keep going. Only stop when you are so exhausted and have viewed the facts every which way and combined them with all other facts.

Step 3

This step is really simple and fun. Drop the entire subject and put the problem out of your mind as completely as you can. Seriously, don't make any effort to think about it. Now you must turn to whatever stimulates your imagination or emotions. Watch a movie, read a book, listen to music, sleep, cook, etc. Keep the problem out of your conscious mind and let your subconscious churn away on the data you have fed it.

I can't tell you how long you need to do this, but you must be patient. The time it takes is probably inversely proportional to how much material you fed your mind and the quality of the relationships, but that is my unscientific guess.

Step 4

Eventually you will have a eureka moment. A great idea will magically pop into your mind when you least expect it. This tends to happen to people during those quiet, isolated times of the day, such as while you shower or just after waking up. Your subconscious has successfully synthesized a new idea from old ideas. It's a pretty amazing thing.

Step 5

This is the final step.

It's likely that your new idea doesn't fit the problem perfectly. You need to shape it and develop it so that it's practical. Get it out into the world of reality and don't stress out if you find it's not as amazing as it seemed when first thought up. It's crucial that you submit the idea to others for analysis, critique, criticism, whatever word you want to call it. You will find that a good idea has self-expanding qualities. It will stimulate those who see it and they will add to it. This will bring light to possibilities that you overlooked.