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Metaprogramming in C++ to create functions that depend on their input parameters

I've been using metaprogramming for a while now. An interesting aspect to the ability to define an invalid (unavailable) type, allows you to declare functions that do not get selected by the C++ template system.

The following is a simple example where you want to test a version where the major, minor and patch version numbers are defined as an undefined type T which could be a signed or an unsigned type while compiling. If unsigned, the return value < 0; statement will generate a warning and for safer programming, you should not allow any warnings (we use the -Werror command line ...

Top 6 Benefits of Hotel Management Software

Technology is ever-changing, and it brings huge operational benefits to all industries, including hospitality. However, not every business has the time, energy, funds, and resources to constantly invest in the latest technological breakthroughs.

That being said, there are a few simple and cost-effective operational aids that are easy to setup and make running a hospitality business that much easier, like hotel management software.

Not sure if you need new software for your hotel? Keep reading to learn how digital hotel management solutions improve efficiency.

Six Tips on How Hotel Software Can Help You

1. Accurate Reports

Hotel ...

5 Simple Ways to Make Your Business More Efficient

There's nothing more frustrating in business than waste. The opportunity cost of your workforce devoting hours to unproductive tasks is something you can't ignore.

So, to help you reduce waste and improve productivity, here are 5 simple ways to help make your business more efficient.

Replace your old mechanism with seemless computer software!

1. Get Software to Manage Your Deliveries

Getting your product delivered to your client is the most important part of your business, but if you don't manage your delivery system carefully, it can also be the most expensive.

Installing job scheduling software allows you to ensure your delivery ...

3 Types of Software Every Business Needs

Are you struggling to stay on top of everything in your business? 

You don't need to handle everything all alone — there's software specifically designed to help your business thrive without you having to put in more hours. The right software will save you time by keeping everything organized and ready to go. 

Learn about the 3 types of software to keep your business running as it should while you focus on more important things. 

Accounting Forms (1099, W2, etc.) with a pocket calculator

What Type of Business Do You Have?

As we go through each type, understand that the software your business needs depends mainly ...

What is the Significance of Tiny PCBs?

A PCB board with drawings of the wires

It’s a common refrain that our electronics are always getting smaller. While there may be some up-and-down fluctuation between one phone release and the next, the broader trend is clear: From speakers, to laptops, to home appliances, we can pack a lot more power into a lot less space these days.

This trend leads to some near-fantastical speculation about where tech can go from here. For instance, Quartz posted about limits in processing power back in 2017, and speculated that light could be built into processing chips as a substitute for what we’d now think ...

Don't Repeat Yourself When Writing Software

Nature tends to repeat itself, or reproduce with similar structure, but code should not.

For a very long time now, we have been using languages that support having functions that one can call. That was not always the case, although even really old versions of BASIC had a GOSUB instruction, which it had no concept of local variables so it was rather difficult to use safely.

Functions allow you to avoid repetition. You write a small snippet of code (or maybe not that small) within a function and then you call that function to reuse that snippet over and over again. Good programmers tend to do that even with one liners. However, many others often think: well, it's just one line, why don't I return copy & paste that wherever I need it, it's going to be faster.

Docker, an advanced chroot utility

Chasm—just like a Docker creates a chasm between two sets of software

SECURITY WARNING

Before installing Docker and containers with services on your Linux system, make sure to read and understand the risks as mentioned on this Docker and iptables page. Especially, Docker will make all your containers visible to the entire world through your Internet connection. This is great if you want to indeed share that service with the rest of the world, it's very dangerous if you are working on that container service since it could have security issues that need patching and such. Docker documents a way to prevent that behavior by adding the following rule to your firewall:

iptables -I DOCKER-USER -i eth0 ! -s 192.168.1.0/24 -j DROP

This means that unless the IP address matches 192.168.1.0/24, the access is refused. The `eth0` interface name should be replaced with the interface name you use as the external ethernet connection. During development, you should always have such a rule.

That has not worked at all for me because my local network includes many other computers on my LAN and this rule blocks them all. So really not a useful idea.

Instead, I created my own entries based on some other characteristics. That includes the following lines in my firewall file:

*filter
:DOCKER-USER - [0:0]

-A DOCKER-USER -j early_forward
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 80 --ctdir ORIGINAL -j DROP
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 8080 --ctdir ORIGINAL -j DROP
-A DOCKER-USER -i eno1 -p tcp -m conntrack --ctorigdstport 8081 --ctdir ORIGINAL -j DROP

My early_forward allows my LAN to continue to work. These are my firewall rules that allow my LAN computers to have their traffic forwarded as expected.

Then I have three rules that block port 80, 8080, and 8081 from Docker.

Docker will add new rules that will appear after (albeit not within the DOCKER-USER list) and will open ports for whatever necessary service you install in your Dockers.

Note that the only ports you have to block are ports that Docker will share and that you have otherwise open on your main server. If Docker opens port 5000 and your firewall does not allow connections to port 5000 from the outside, then you're already safe. On my end I have Apache running so as a result I block quite usual HTTP ports from Docker.

Docker

As we are helping various customers, we encounter new technologies.

In the old days, we used chroot to create a separate environment where you could have your own installation and prevent the software from within that environment access to everything on your computer. This is particularly useful for publicly facing services liek Apache, Bind, etc.

Help with version 0.1.7 of Zipios (CVE-2019-13453)

Here is yet another example of why opensource is a really good way of getting things fixed.

Assuming you have a project that is getting used by many, you are likely to see people post issues about bugs and possible enhancements. Your software is even very likely to get improved on its own by enthousiast users. On Github, for example, it is very easy to fork a project (make a copy) and then work on your version of the software. You can then offer a fix to the main authors of the project with a near one to one copy of the project.

In our case, a security professional, Mike Salvatore, was asked ...

Best C++ Books

Once in a while someone will ask me which book is best to start learning programming. The fact is that I do not know because I'm already an advanced programmer and it's rather difficult for me to get back to the basics (it feels like a waste of my time, sorry...)

That being said, at Made to Order Software, we've mainly been a C++ shop. We also do a lot of C, PHP, JavaScript and touch many other languages as required by the tasks we perform (bash, cmake, perl, C#, Java, etc.)

That being said, I wanted to underline some of the best C++ books available today. Especially, in the last ...

Put the label of an HTML Input inside the Input element

Reflection of trees in a mountain lake.

Update:

With HTML5 running on pretty much all platforms, you want to use the placeholder attribute instead of any sort of tricks to place a label inside your input widgets.

This is done like this:

<input type="text" placeholder="Phone Number"/>

This example will show "Phone Number" inside the input box until the user types some text in that box.

You can test with the box right here. This is just that one <input .../> tag I placed in my page HTML. (It is not in a form, but the widget itself will work as expected.)

For additional details, I ...