I'm trying to copy a range of Excel cells between two different sheets using Excel automation via C++. I am using excel8.cpp to interface with Excel.
I want to call the Range.Copy method but I'm not sure how exactly to pass the destination parameter. I think this is the correct way:
//ranges already defined
//XL::Range range1, range2;
COleVariant myVar;
VariantInit(myVar);
myVar.vt = VT_DISPATCH;
myVar.pdispVal = (LPDISPATCH)range2;
range1.Copy(myVar);
However when I try this, I get the message "Copy method of Range class failed".
Also, I don't want to pass an optional Variant into the copy function because there is a bug I have come across with the clipboard causing Copy and Paste to fail randomly.
Related
I am learning with some small projects and I don't know, how to access XAML element from C++ code.
Can you help me please?
It says "cannot determine which instance of overloaded function is intended",
screenshot: https://pasteboard.co/JjjKCAT.png
Thank you
Lukas
When creating something in XAML, it creates two methods with the same name, one that returns that object and takes 0 arguments, and one that returns nothing (aka a void) and takes one element of that type. In your case, if you want to retrieve the value, you need to the following:
void MainWindow::Button_Click_Ring(...)
{
// Get the ProgressRing:
const auto progressRing = ProgressRing1();
// Set the ProgressRing:
ProgressRing1(newValue /* the new value */);
}
Let me elaborate on the title:
I want to implement a system that would allow me to enable/disable/modify the general behavior of my program. Here are some examples:
I could switch off and on logging
I could change if my graphing program should use floating or pixel coordinates
I could change if my calculations should be based upon some method or some other method
I could enable/disable certain aspects like maybe a extension api
I could enable/disable some basic integrated profiler (if I had one)
These are some made-up examples.
Now I want to know what the most common solution for this sort of thing is.
I could imagine this working with some sort of singelton class that gets instanced globally or in some other globally available object. Another thing that would be possible would be just constexpr or other variables floating around in a namespace, again globally.
However doing something like that, globally, feels like bad practise.
second part of the question
This might sound like I cant decide what I want, but I want a way to modify all these switches/flags or whatever they are actually called in a single location, without tying any of my classes to it. I don't know if this is possible however.
Why don't I want to do that? Well I like to make my classes somewhat reusable and I don't like tying classes together, unless its required by the DRY principle and or inheritance. I basically couldn't get rid of the flags without modifying the possible hundreds of classes that used them.
What I have tried in the past
Having it all as compiler defines. This worked reasonably well, however I didnt like that I couldnt make it so if the flag file was gone there were some sort of default settings that would make the classes themselves still operational and changeable (through these default values)
Having it as a class and instancing it globally (system class). Worked ok, however I didnt like instancing anything globally. Also same problem as above
Instancing the system class locally and passing it to the classes on construction. This was kinda cool, since I could make multiple instruction sets. However at the same time that kinda ruined the point since it would lead to things that needed to have one flag set the same to have them set differently and therefore failing to properly work together. Also passing it on every construction was a pain.
A static class. This one worked ok for the longest time, however there is still the problem when there are missing dependencies.
Summary
Basically I am looking for a way to have a single "place" where I can mess with some values (bools, floats etc.) and that will change the behaviour of all classes using them for whatever, where said values either overwrite default values or get replaced by default values if said "place" isnt defined.
If a Singleton class does not work for you , maybe using a DI container may fit in your third approach? It may help with the construction and make the code more testable.
There are some DI frameworks for c++, like https://github.com/google/fruit/wiki or https://github.com/boost-experimental/di which you can use.
If you decide to use switch/flags, pay attention for "cyclometric complexity".
If you do not change the skeleton of your algorithm but only his behaviour according to the objets in parameter, have a look at "template design pattern". This method allow you to define a generic algorithm and specify particular step for a particular situation.
Here's an approach I found useful; I don't know if it's what you're looking for, but maybe it will give you some ideas.
First, I created a BehaviorFlags.h file that declares the following function:
// Returns true iff the given feature/behavior flag was specified for us to use
bool IsBehaviorFlagEnabled(const char * flagName);
The idea being that any code in any of your classes could call this function to find out if a particular behavior should be enabled or not. For example, you might put this code at the top of your ExtensionsAPI.cpp file:
#include "BehaviorFlags.h"
static const enableExtensionAPI = IsBehaviorFlagEnabled("enable_extensions_api");
[...]
void DoTheExtensionsAPIStuff()
{
if (enableExtensionsAPI == false) return;
[... otherwise do the extensions API stuff ...]
}
Note that the IsBehaviorFlagEnabled() call is only executed once at program startup, for best run-time efficiency; but you also have the option of calling IsBehaviorFlagEnabled() on every call to DoTheExtensionsAPIStuff(), if run-time efficiency is less important that being able to change your program's behavior without having to restart your program.
As far as how the IsBehaviorFlagEnabled() function itself is implemented, it looks something like this (simplified version for demonstration purposes):
bool IsBehaviorFlagEnabled(const char * fileName)
{
// Note: a real implementation would find the user's home directory
// using the proper API and not just rely on ~ to expand to the home-dir path
std::string filePath = "~/MyProgram_Settings/";
filePath += fileName;
FILE * fpIn = fopen(filePath.c_str(), "r"); // i.e. does the file exist?
bool ret = (fpIn != NULL);
fclose(fpIn);
return ret;
}
The idea being that if you want to change your program's behavior, you can do so by creating a file (or folder) in the ~/MyProgram_Settings directory with the appropriate name. E.g. if you want to enable your Extensions API, you could just do a
touch ~/MyProgram_Settings/enable_extensions_api
... and then re-start your program, and now IsBehaviorFlagEnabled("enable_extensions_api") returns true and so your Extensions API is enabled.
The benefits I see of doing it this way (as opposed to parsing a .ini file at startup or something like that) are:
There's no need to modify any "central header file" or "registry file" every time you add a new behavior-flag.
You don't have to put a ParseINIFile() function at the top of main() in order for your flags-functionality to work correctly.
You don't have to use a text editor or memorize a .ini syntax to change the program's behavior
In a pinch (e.g. no shell access) you can create/remove settings simply using the "New Folder" and "Delete" functionality of the desktop's window manager.
The settings are persistent across runs of the program (i.e. no need to specify the same command line arguments every time)
The settings are persistent across reboots of the computer
The flags can be easily modified by a script (via e.g. touch ~/MyProgram_Settings/blah or rm -f ~/MyProgram_Settings/blah) -- much easier than getting a shell script to correctly modify a .ini file
If you have code in multiple different .cpp files that needs to be controlled by the same flag-file, you can just call IsBehaviorFlagEnabled("that_file") from each of them; no need to have every call site refer to the same global boolean variable if you don't want them to.
Extra credit: If you're using a bug-tracker and therefore have bug/feature ticket numbers assigned to various issues, you can creep the elegance a little bit further by also adding a class like this one:
/** This class encapsulates a feature that can be selectively disabled/enabled by putting an
* "enable_behavior_xxxx" or "disable_behavior_xxxx" file into the ~/MyProgram_Settings folder.
*/
class ConditionalBehavior
{
public:
/** Constructor.
* #param bugNumber Bug-Tracker ID number associated with this bug/feature.
* #param defaultState If true, this beheavior will be enabled by default (i.e. if no corresponding
* file exists in ~/MyProgram_Settings). If false, it will be disabled by default.
* #param switchAtVersion If specified, this feature's default-enabled state will be inverted if
* GetMyProgramVersion() returns any version number greater than this.
*/
ConditionalBehavior(int bugNumber, bool defaultState, int switchAtVersion = -1)
{
if ((switchAtVersion >= 0)&&(GetMyProgramVersion() >= switchAtVersion)) _enabled = !_enabled;
std::string fn = defaultState ? "disable" : "enable";
fn += "_behavior_";
fn += to_string(bugNumber);
if ((IsBehaviorFlagEnabled(fn))
||(IsBehaviorFlagEnabled("enable_everything")))
{
_enabled = !_enabled;
printf("Note: %s Behavior #%i\n", _enabled?"Enabling":"Disabling", bugNumber);
}
}
/** Returns true iff this feature should be enabled. */
bool IsEnabled() const {return _enabled;}
private:
bool _enabled;
};
Then, in your ExtensionsAPI.cpp file, you might have something like this:
// Extensions API feature is tracker #4321; disabled by default for now
// but you can try it out via "touch ~/MyProgram_Settings/enable_feature_4321"
static const ConditionalBehavior _feature4321(4321, false);
// Also tracker #4222 is now enabled-by-default, but you can disable
// it manually via "touch ~/MyProgram_Settings/disable_feature_4222"
static const ConditionalBehavior _feature4222(4222, true);
[...]
void DoTheExtensionsAPIStuff()
{
if (_feature4321.IsEnabled() == false) return;
[... otherwise do the extensions API stuff ...]
}
... or if you know that you are planning to make your Extensions API enabled-by-default starting with version 4500 of your program, you can set it so that Extensions API will be enabled-by-default only if GetMyProgramVersion() returns 4500 or greater:
static ConditionalBehavior _feature4321(4321, false, 4500);
[...]
... also, if you wanted to get more elaborate, the API could be extended so that IsBehaviorFlagEnabled() can optionally return a string to the caller containing the contents of the file it found (if any), so that you could do shell commands like:
echo "opengl" > ~/MyProgram_Settings/graphics_renderer
... to tell your program to use OpenGL for its 3D graphics, or etc:
// In Renderer.cpp
std::string rendererType;
if (IsDebugFlagEnabled("graphics_renderer", &rendererType))
{
printf("The user wants me to use [%s] for rendering 3D graphics!\n", rendererType.c_str());
}
else printf("The user didn't specify what renderer to use.\n");
I've scoured the web and stackoverflow for this answer but can't find anything. I have written a com object in C++ (for the fist time) that works when used in vbscript and through cocreateinstance in an executable file. So I decided to see if it would work in Excel VBA.
So I went into "References" and located my object there. Checked the box and started coding away. The following is the VBA code.
Function doCos(x As Double) As Double
Dim t As SimpleLib.IMath
Set t = New SimpleLib.IMath ' <- "Invalid use of New keyword" error here
doCos = t.Cos(x)
End Function
Intellisense recognizes my object in the Dim statement, but it does not appear when I use a Set statement. Obviously I am using a registered type library or else intellisense wouldn't work at all. Again, the com object can be used in vbscript or an executable, but for some reason can't be used, at least with the new keyword, in VBA.
Does anyone have an idea what may be wrong, or what may have to be added to the com object? Thanks.
One approach is to define a coclass in the IDL that includes the interface needed (IMath in my case). NOTE: That the [default] interface is hidden by default. So I simply defined interface IUnknown as the default. After compiling with MIDL a type library is generated which one should register with regtlibv12.exe.
I then included an additional IF statement in DllGetClassObject like if (rclsid == CLSID_Math) where CLSID_Math is corresponds to the CLSID defined in the file automatically generated from MIDL. All I did was copy and paste the body of the IF statement from if ( rclsid == IID_IMath ), updated the DLLRegisterServer and DLLUnRegisterServer functions, recompiled the project, and regsvr32.exe.
So the following works now.
Function docos(x As Double) As Double
Dim a As SimpleLib.IMath
Set a = New SimpleLib.Math
docos = a.Cos(x)
End Function
Thanks to Hans for the tip about the coclass. Learned something new and useful.
I'm using a simple numeric text validator wxTextValidator along with a wxTextControl. I wonder what the 2nd parameter is good for:
wxTextValidator(long style = wxFILTER_NONE, wxString* valPtr = NULL)
I simply passed the reference to a member variable:
myTextControl_->SetValidator( wxTextValidator(wxFILTER_NUMERIC, &myValue_) );
I'm using wxWidgets 2.8.12, from the documentation I figured that the myValue_ variable would receive the validated content of the text control, but this does not happen in my application.
Am I doing something wrong or does the valPtr parameter not receive the content of the text control?
The myvalue_ variable should receive the value entered if you call wxValidator::Validate or wxValidator::TransferFromWindow. This happens automatically if you close the dialog with the default OnOK() handler. Otherwise you have to do it yourself.
Ravenspoint has already answered the initial question but I'd just like to add that wxValidator can be used either for validating or for data transfer -- or for both at once. In fact, some validators, such as wxGenericValidator are only used for data transfer (it doesn't make much sense to validate a check box or a radio button!). So the name of this class is somewhat misleading as it describes at most half, and probably less than that, of its uses.
I'm trying to do the following trick:
I have IDataObject* to be set into the clipboard, so I'm using OleSetClipboard() to set it into the clipboard.
I have another CLIPFORMAT I want to add to the clipboard, but I can't do it with OleSetClipboard() because the IDataObject* I receive does not implement SetData() method. So, to overcome this limitation I OpenClipboard() with GetClipboardOwner(), this way, I can SetClipboardData() to the clipboard without EmptyClipboard() first.
Now, it all works well, but what happens is that OleGetClipboard() does not return the data I placed in the clipboard using SetClipboardData(), but I can using GetClipboardData().
I can imagine why this happens (It just returns the IDataObject*), so I tried to OleFlushClipboard() to delete the IDataObject*, and OleGetClipboard() again to let the OS rebuild a new IDataObject*, and it still didn't contain the CLIPFORMAT added by SetClipboardData().
Does anyone have any idea how to overcome this issue? or a different trick? or even explain why it works this way? Thanks
I just tried this (on Windows 7) and it appears to work but only cross-process:
In a different process to the clipboard owner, OleGetClipboard returns a data object that contains all of the formats (i.e. the original formats from the data object and the extra ones added to the clipboard).
In the same process, OleGetClipboard always returns a data object that does not contain the extra clipboard formats.
In both cases, calling OleFlushClipboard makes no difference.
Anyway, this doesn't seem like a terribly robust solution. What you can do instead is create your own data object that responds to the formats it knows about and delegates other formats to the original data object. The EnumFormatEtc method would combine formats from both objects, and so on. This article has the skeleton of a simple data object you could extend.