__FILE__, __LINE__ and __FUNCTION__ for QML files?

Question

As a project I am working on is getting bigger I am getting tired of writing comprehensive log messages, needed to find out what went wrong and where.

So it would be extremely useful if I can incorporate that information into the messages automatically. For C++ we have the convenient __FILE__, __LINE__ and __FUNCTION__ macros, but I don't seem to find any for QML.

Note that there is console.trace() which outputs a trace in the console in the following format:

onCompleted (qrc:/main.qml:72)

So it includes function, file and line, which is all I need, therefore I assume there already exists a way to get those. Natural, console.trace() doesn't really quite cut it, because it directly outputs to the console, whereas I need those as strings to incorporate in my log messages.

So is there any way to get those?

Naturally I don't want to get them in the actual QML source, but the same way console.trace() does - on the spot where my Log.error() is invoked, so I can just Log.error("some error") instead of Log.error("some error in " + file + ", at " + line + " while executing " + func) which will actually be even more tedious than writing the whole thing manually.

Alternatively, I'd also appreciate if someone can point me to the implementation of the qml console, because I combed through the entire qtdeclarative code base for "console" and found nothing.

Note that I already found this, however it isn't of use to me, because I need that for a specific subset of messages and don't want to override the default message handler for all output.

Answer 1

console.log, console.debug, console.info, console.warn and console.error can be used to print debugging information to the console. The output is generated using the qDebug, qWarning, qCritical methods in C++ (see also Debugging Techniques and how such functions are implemented, especially this internal function). Setting the environment variable QML_CONSOLE_EXTENDED also prints the source code location of the call. For example,

export QT_MESSAGE_PATTERN="[%{type}] %{appname} (%{file}:%{line}) - %{message}"

Now the output looks like this,

This link contains details about customizing the QT_MESSAGE_PATTERN environment variable.