Danger of using default values in declarations

Working on a large project using C++, recently faced a dangerous things during
debugging. Let’s see in examples. Once there was a method:

Class1::SetEditBox(CString const& value, bool isUppercase = true);

Somewhere it was used differently:

obj1.SetEditBox(_T("Volume"), false);

After a while this declaration was a bit extended:

Class1::SetEditBox(CString const& value, bool isEditable = false, bool isUppercase = true);

New places were using it properly, but not all that old places were changed, so

obj1.SetEditBox(_T("Volume"), false);

became to have isUppercase = true, however, since volume is usually numeric,
this was not detected during “happy way” testing.
Meanwhile system became more complex. Refactored and rewritten, developers were
also changing. Inheritance and other OOP stuff started to using this method:

Class2::SetListEdit(CString const& value, bool isEditable = false, bool isUppercase = true)
    // ...
    obj4.SetEditBox(value, isEditable, isUppercase);
    // ...

And again time passed, things changed, and so changed method declaration:

Class1::SetEditBox(CString const& value, bool isNumeric = true, bool isEditable = false, bool isUppercase = true);

Now there were even more things to recheck and update, but guess what?
Somebody, who did this change did not care about looking up every place to change
and now it became the bug, which I called “Shifting Boolean”:

Class3::AddListEdit(CString const& value, bool isUppercase = true)
    Class2 obj5;
    obj5.SetListEdit(value, isUppercase);

So the call to Class3::AddListEdit() and passing only CString value, made
isUppercase default value bacame isEditable in Class2::SetListEdit() and then
to became isNumeric in Class1::SetEditBox().

If there were no default values, all the differences would come out during
compilation, or even earlier, in IDE. However there are a trade-offs: either
you save typing and introduce default values, or make changes more transparent.

In any case, every change that can be interpreted by implicit type conversion
should be carefully examined and all the places should be changed as required.

It took me about 6 hours to refactor all the project code and get rid of this
bug. In my solution I have replaced booleans with a single enum argument, because
all the booleans were tightly coupled, and in the end switch()-ing between
enumerated values was easier than checking all the boolean combinations.

Omniva Rounding

Omniva (former Eesti Post) company sent me a message recently about the package which needed customs clearance.
However, it seems, that they have saved a penny on testing their software, that is generating such messages, especially the part about parcel weight.
I should feel lucky, that I haven’t received anything too large or too small to get an exponential formatting.
Omniva Rounding

320×480 ILI9481 based touch LCD

Until recently, I was using cell phone displays in my hobby projects.

But now I have received the bigger screen, which is almost 3.5 inch and has 320×480 pixels resolution and a touch sensor.

Since the LCD requires 3.3 volts and 16 data lines, I could not connect it to Arduino, so I got my Stellaris Launchpad board and connected display with it.

Quick search on the internet revealed, that we already have excellent UTFT library for various graphical LCDs and moreover, it is already ported for Energia IDE.

So I have downloaded that, and run one of the examples to check the display.

Reanimating the router

My Linksys WRT610N seemed to be almost dead in peripherals.

I’ve decided, that I have nothing to loose and performed hard reset.

After router booted up, I have reconfigured it manually and everything worked perfectly: internet, even both Wi-Fi interfaces.

Had to dig internet a bit to recall on VPN configuration, but eventually VPN works also.

My guess is that during power loss occurrences the voltage from power supply felled too slowly and that lead to flash memory corruption where the settings are held.

Implicitly it is proved by the fact, I have switched electricity many times off and on just previous two days before failure.

Home router failed

Now I am without internet.

It has failing Wi-Fi second channel some time ago in the beginning of the year.

And today I have checked the VPN and it did not worked. Checked the dashboard and found out, that USB drive did not mount.

Have tried to mount it by hand, but even could not get USB core driver to work.

After reboot the PPPoE internet connection also failed.

So I suspect either router processor has issue or the power supply.

How many programmers required to fix the lamp

Eventually decided to change the ceiling light fixture in the room.

The difference between new and old fixtures is that the latter hangs on ceiling hook and the new one should be fixed with two screws.

I have checked the ceiling wiring, and also have drawn the whole flat schema.

Started to drill the holes for screws. The first hole went well, but the second was the pain. Other side of the ceiling from the hook is totally plaster :(

That wouldn’t be a problem, if I hadn’t to hide the hook and the wires.

So I had to put the new fixture aside and to start thinking about two possible solutions:

  1. hide the hook and the wires with the wiring box, and drill the holes for fixture a bit farther
  2. cover the plaster part with some wooden or plastic plate and screw fixture on to the plate.