Qt error is printed on the console; how to see where it originates from? - qt

I'm getting this on the console in a QML app:
QFont::setPointSizeF: Point size <= 0 (0.000000), must be greater than 0
The app is not crashing so I can't use the debugger to get a backtrace for the exception. How do I see where the error originates from?

If you know the function the warning occurs in (in this case, QFont::setPointSizeF()), you can put a breakpoint there. Following the stack trace will lead you to the code that calls that function.
If the warning doesn't include the name of the function and you have the source code available, use git grep with part of the warning to get an idea of where it comes from. This approach can be a bit of trial and error, as the code may span more than one line, etc, and so you might have to try different parts of the string.
If the warning doesn't include the name of the function, you don't have the source code available and/or you don't like the previous approach, use the QT_MESSAGE_PATTERN environment variable:
QT_MESSAGE_PATTERN="%{function}: %{message}"
For the full list of variables at your disposal, see the qSetMessagePattern() docs:
%{appname} - QCoreApplication::applicationName()
%{category} - Logging category
%{file} - Path to source file
%{function} - Function
%{line} - Line in source file
%{message} - The actual message
%{pid} - QCoreApplication::applicationPid()
%{threadid} - The system-wide ID of current thread (if it can be obtained)
%{qthreadptr} - A pointer to the current QThread (result of QThread::currentThread())
%{type} - "debug", "warning", "critical" or "fatal"
%{time process} - time of the message, in seconds since the process started (the token "process" is literal)
%{time boot} - the time of the message, in seconds since the system boot if that can be determined (the token "boot" is literal). If the time since boot could not be obtained, the output is indeterminate (see QElapsedTimer::msecsSinceReference()).
%{time [format]} - system time when the message occurred, formatted by passing the format to QDateTime::toString(). If the format is not specified, the format of Qt::ISODate is used.
%{backtrace [depth=N] [separator="..."]} - A backtrace with the number of frames specified by the optional depth parameter (defaults to 5), and separated by the optional separator parameter (defaults to "|"). This expansion is available only on some platforms (currently only platfoms using glibc). Names are only known for exported functions. If you want to see the name of every function in your application, use QMAKE_LFLAGS += -rdynamic. When reading backtraces, take into account that frames might be missing due to inlining or tail call optimization.
On an unrelated note, the %{time [format]} placeholder is quite useful to quickly "profile" code by qDebug()ing before and after it.

I think you can use qInstallMessageHandler (Qt5) or qInstallMsgHandler (Qt4) to specify a callback which will intercept all qDebug() / qInfo() / etc. messages (example code is in the link). Then you can just add a breakpoint in this callback function and get a nice callstack.

Aside from the obvious, searching your code for calls to setPointSize[F], you can try the following depending on your environment (which you didn't disclose):
If you have the debugging symbols of the Qt libs installed and are using a decent debugger, you can set a conditional breakpoint on the first line in QFont::setPointSizeF() with the condition set to pointSize <= 0. Even if conditional breakpoints don't work you should still be able to set one and step through every call until you've found the culprit.
On Linux there's the tool ltrace which displays all calls of a binary into shared libs, and I suppose there's something similar in the M$ VS toolbox. You can grep the output for calls to setPointSize directly, but of course this won't work for calls within the lib itself (which I guess could be the case when it handles the QML internally).

Related

Xcos throws "Undefined variable: scifunc_block_m" message in console

When I run a Xcos model containing a scifunc_block_m block like shown below
I get an error message relating to data dimensions inconsistency:
"Data dimensions are inconsistent:"
" Variable size=[1,1]"
"Block output size=[100,1]."
But when I double click in the block in order to see what can I change to make the dimensions correct I get a message in the console saying
Undefined variable: scifunc_block_m
What bugs me is that scifunc_block_m is not the name of any variable, but rather the name of the block itself like can be seen in the official docs.
Of course I double checked that nowhere in my function phase_shifter neither anywhere else I have any variable named like that.
I tried with Scilab 6.1.1 and 6.1.0 believing that it might be a bug from apparently not.
In your phase_shifter.sce file generating the input variable,
the signalIn variable does not comply with the From Workspace block requirements, whose documentation says that the input variable
must be a structure with time and values fields
.time must be a column vector, and in your case
.values must also be a column
So,
t = (0:1/fs:Npp/fs - 1/fs); // time vector
signalIn = A*%e^(%i*w*t);
should be replaced with
t = (0:1/fs:Npp/fs - 1/fs)'; // time column vector
signalIn = struct("time",t, "values",A*%e^(%i*w*t));
This fixes the inconsistent dimensions message.
In addition, i am not able to reproduce your issue about Undefined variable: scifunc_block_m. The parameters interface opens as expected.
You may get this kind of messages if you try to run some xcos parts out of xcos, without beforehand loading xcos-related libraries.
Then, we get an unclear "Output should be of complex type." message on the From workspace block.
By the way, you try to plot some complex values. Please have a look to the MATMAGPHI block before entering MUX: https://help.scilab.org/docs/6.1.1/en_US/MATMAGPHI.html

First token could not be read or is not the keyword 'FoamFile' in OpenFOAM

I am a beginner to programming. I am trying to run a simulation of a combustion chamber using reactingFoam.
I have modified the counterflow2D tutorial.
For those who maybe don't know OpenFOAM, it is a programme built in C++ but it does not require C++ programming, just well-defining the variables in the files needed.
In one of my first tries I have made a very simple model but since I wanted to check it very well I set it to 60 seconds with a 1e-6 timestep.
My computer is not very powerful so it took me for a day aprox. (by this I mean I'd like to find a solution rather than repeating the simulation).
I executed the solver reactingFOAM using 4 processors in parallel using
mpirun -np 4 reactingFOAM -parallel > log
The log does not show any evidence of error.
The problem is that when I use reconstructPar it works perfectly but then I try to watch the results with paraFoam and this error is shown:
From function bool Foam::IOobject::readHeader(Foam::Istream&)
in file db/IOobject/IOobjectReadHeader.C at line 88
Reading "mypath/constant/reactions" at line 1
First token could not be read or is not the keyword 'FoamFile'
I have read that maybe some files are empty when they are not supposed to be so, but I have not found that problem.
My 'reactions' file have not been modified from the tutorial and has always worked.
edit:
Sorry for the vague question. I have modified it a bit.
A typical OpenFOAM dictionary file always contains a Foam::Istream named FoamFile. An example from a typical system/controlDict file can be seen below:
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "system";
object controlDict;
}
During the construction of the dictionary header, if this Istream is absent, OpenFOAM ceases its operation by raising an error message that you have experienced:
First token could not be read or is not the keyword 'FoamFile'
The benefit of the header is possibly to contribute OpenFOAM's abstraction mechanisms, which would be difficult otherwise.
As mentioned in the comments, adding the header entity almost always solves this problem.

How do I determine whether a julia script is included as module or run as script?

I would like to know how in the Julia language, I can determine if a file.jl is run as script, such as in the call:
bash$ julia file.jl
It must only in this case start a function main, for example. Thus I could use include('file.jl'), without actually executing the function.
To be specific, I am looking for something similar answered already in a python question:
def main():
# does something
if __name__ == '__main__':
main()
Edit:
To be more specific, the method Base.isinteractive (see here) is not solving the problem, when using include('file.jl') from within a non-interactive (e.g. script) environment.
The global constant PROGRAM_FILE contains the script name passed to Julia from the command line (it does not change when include is called).
On the other hand #__FILE__ macro gives you a name of the file where it is present.
For instance if you have a files:
a.jl
println(PROGRAM_FILE)
println(#__FILE__)
include("b.jl")
b.jl
println(PROGRAM_FILE)
println(#__FILE__)
You have the following behavior:
$ julia a.jl
a.jl
D:\a.jl
a.jl
D:\b.jl
$ julia b.jl
b.jl
D:\b.jl
In summary:
PROGRAM_FILE tells you what is the file name that Julia was started with;
#__FILE__ tells you in what file actually the macro was called.
tl;dr version:
if !isdefined(:__init__) || Base.function_module(__init__) != MyModule
main()
end
Explanation:
There seems to be some confusion. Python and Julia work very differently in terms of their "modules" (even though the two use the same term, in principle they are different).
In python, a source file is either a module or a script, depending on how you chose to "load" / "run" it: the boilerplate exists to detect the environment in which the source code was run, by querying the __name__ of the embedding module at the time of execution. E.g. if you have a file called mymodule.py, it you import it normally, then within the module definition the variable __name__ automatically gets set to the value mymodule; but if you ran it as a standalone script (effectively "dumping" the code into the "main" module), the __name__ variable is that of the global scope, namely __main__. This difference gives you the ability to detect how a python file was ran, so you could act slightly differently in each case, and this is exactly what the boilerplate does.
In julia, however, a module is defined explicitly as code. Running a file that contains a module declaration will load that module regardless of whether you did using or include; however in the former case, the module will not be reloaded if it's already on the workspace, whereas in the latter case it's as if you "redefined" it.
Modules can have initialisation code via the special __init__() function, whose job is to only run the first time a module is loaded (e.g. when imported via a using statement). So one thing you could do is have a standalone script, which you could either include directly to run as a standalone script, or include it within the scope of a module definition, and have it detect the presence of module-specific variables such that it behaves differently in each case. But it would still have to be a standalone file, separate from the main module definition.
If you want the module to do stuff, that the standalone script shouldn't, this is easy: you just have something like this:
module MyModule
__init__() = # do module specific initialisation stuff here
include("MyModule_Implementation.jl")
end
If you want the reverse situation, you need a way to detect whether you're running inside the module or not. You could do this, e.g. by detecting the presence of a suitable __init__() function, belonging to that particular module. For example:
### in file "MyModule.jl"
module MyModule
export fun1, fun2;
__init__() = print("Initialising module ...");
include("MyModuleImplementation.jl");
end
### in file "MyModuleImplementation.jl"
fun1(a,b) = a + b;
fun2(a,b) = a * b;
main() = print("Demo of fun1 and fun2. \n" *
" fun1(1,2) = $(fun1(1,2)) \n" *
" fun2(1,2) = $(fun2(1,2)) \n");
if !isdefined(:__init__) || Base.function_module(__init__) != MyModule
main()
end
If MyModule is loaded as a module, the main function in MyModuleImplementation.jl will not run.
If you run MyModuleImplementation.jl as a standalone script, the main function will run.
So this is a way to achieve something close to the effect you want; but it's very different to saying running a module-defining file as either a module or a standalone script; I don't think you can simply "strip" the module instruction from the code and run the module's "contents" in such a manner in julia.
The answer is available at the official Julia docs FAQ. I am copy/pasting it here because this question comes up as the first hit on some search engines. It would be nice if people found the answer on the first-hit site.
How do I check if the current file is being run as the main script?
When a file is run as the main script using julia file.jl one might want to activate extra functionality like command line argument handling. A way to determine that a file is run in this fashion is to check if abspath(PROGRAM_FILE) == #__FILE__ is true.

how to increase buffer size in scilab

I'm using a variable that is using too large symbol/string in Scilab, which is giving following error:
Too large string. at line 44 of exec file called by :
exec('/proj/shubhamj/shubhamj/scilab/final_add_from_script.sce', -1)
I've already used stacksize('max').
According to this thread on the mailing list for Scilab the error comes from the length of the command. You can get the same error without the exec() if you call a command that is too long even in your current script (where the exec() call currently is).
If we look at the documentation the default stacksize is approx. 76MB (megabytes) and that is a lot of characters which makes this issue 99.9% not related to the size of the stack.

Are there any equivalent of C/C++ __FILE__ and __LINE__ macros in R?

I'm trying to get the equivalent of FILE or LINE macros in C or C++ in R (or S+). Any ideas?
FILE The presumed name of the current source file (a character string literal).
LINE The presumed line number (within the current source file) of the current source line (an integer constant).
As for context - I have log messages being flushed to console from different sections of the code, and given that the messages themselves are built at run-time, it is often very difficult to find out where this log message is coming from (with the size of the R code growing to many thousand lines and running on a distributed grid). However if I could dump the FILE and LINE number along with the log messages, it would be much easier to trace the logs...
Use the #line directive. The structure is #line nn "filename". See Duncan's Murdoch's article on source references for more.

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