Delphi - Class TListView not found - delphi

We have a Delphi 5 application, that is built without runtime packages, dlls or external resources (i.e. a single executable). when we install it on a clients PC we get the following error messages:
Class TListView not found
or
Class TImage not found
We have installed it on dozens of PCs before without incident, but this latest install is problematic.
The target PC is a fresh install of Windows XP (Service pack 3) with no other software installed.
It does not complain about all of the classes however just one or two. for example TPanel/ TForm/ TEdit are all OK.
Can anyone think what is causing this?
EDIT
The exe on the new PC is on 30 or so other PCs that I know of, ranging from windows XP Sp1,2,3, Windows Vista and Windows embedded. both old and new PCs were installed with an old version and then updated with the newest version. The only difference is that the version jump was higher for the latest install.

This is typically an error during the streaming of a .DFM. Usually this error occurs with TLabel components because many folks remove the TLabel fields from the form or frame in order to cut down on the clutter and reduce the instance size of the form. The common and confusing mistake they make, however, is that in their over-zealousness, they remove all TLabel references. That is when bad things start to happen. Let me run down how the streaming system locates a component's class.
Remember that the class reference in the .DFM is just a string. The streaming system has to convert this string into a class reference (TComponentClass). There are two mechanisms that the streaming system uses to do this. The first one is very simple and involves a global list of class references. You can call RegisterClass or RegisterClasses to explicitly make the streaming system aware of it. The second is much more subtle and not very well known; in fact it is all part of the "magic" of Delphi :-). When the compiler builds the form, all the fields that represent the components on the form are processed and an internal table is built as part of the RTTI or metadata for the form/frame/datamodule itself. This table contains a list of references to all the individual component types represented by the component fields. So even if a component is not in the global list, it can still be found by scanning through this compiler generated table. That is what the Classes.TReader.GetFieldClass() method does.
Back to my TLabel example, this problem is easily fixed by simply ensuring that at least one of a given component type has a field. So as long as there is at least field of type TLabel, all the other TLabels will load just fine. So in your case, make sure the TListView or TImage fields haven't been deleted.

Re0sless,
I suggest you open and close every form of your application and do a fresh build after that. If memory serves me well, that was the solution when we encountered similar problems.
You might also take a look at DFM Check to open and close all your dfm's automatically and at CnPack to help you clean your uses clause.
Regards,
Lieven

I think Lieven is definitely on the right track: simple base classes not being found during runtime are a Delphi (linker) problem. This exception is not caused by the Operating System.
My experience with similar problems: the linker generates a project with the units wrongly arranged.
Example: a form unit is linked in before the base units. Forcing the project to completely recompile/relink itself should make this exception go away.
A simple [Rebuild All] will probably not suffice. You might try to recompile without optimizations.
I have tried to reproduce this error but I have not been able to. The Delphi compiler/linker is one of the best - speed of compilation/speed of compiled exes - but this bug is definitely a show stopper.
Note: I have only experienced
this error in D5. Has anybody else
experienced this error with other
Delphi versions?

I had the same problem. Class TCheckBox not found. I usually edit large set of components through .DFM of form(for example renaming large amount of component). This error comes when I rename all CheckBox on my form through it .DFM.
I just cut all the checkbox and paste them again(So .DFM file is refreshed). The error disappeared.

I've seen a similar problem due to a file copy error. To make matters more confusing, the fault was on an intermediate media device. The issue was resolved by simply recopying the file from the existing release build.
It is probably impossible to confirm now, but it is quite possible that the problem was 'solved'; not because of the removal of an unnecessay uses clause item, but because it also involved a new copy of the executable.

The solution for all errors of this type "Class XXX not found" is simple. Open DFM file of a form in text editor and manualy remove the definition of the XXX object in it.

Change the name of the Form and save the .pas with other name. Change all references to create the new unit name if this is used in other units. Build All.
With this the error disappeared.

Related

Random error when loading project into Delphi XE6

From time to time, when I load a project into the XE6 IDE, the following error occurs
This error results in the TZConnection component being removed from the Datamodule for some inexplicable reason. Note that the project has been loading without issue for ages and just out of the blue, this occurs.
Has anyone seen this before and know of a way of stopping it from occuring ?
It also occurs with other components, not always the TZConnection component but mostly ZConnection.
Like I said before, this appears randomly. I could close project A, open project B then close it and return to Project A and bang!, the error occurs.
Any clues ? (note that this also used to occur in Delphi 2007)
The Zeos libraries are themselves causing this problem.
To see why, and to fix it, use Delphi to launch a second instance of Delphi, and debug the issue directly.
I wrote a blog post showing exact steps here.
The key is to set the executable that will be run for your zeos package, be sure to build them in debug configuration, and then click the Run button on the Delphi IDE toolbar. A second delphi instance will start. Open the affected form but be sure to be using the IDE instance that is Being debugged as opposed to the one which is currently doing the debugging, when the exception occurs that is causing your component to delete itself, you will be able to step into the package code and see the problem.
I suspect a DLL-hell path issue. (Multiple copies of Zeos or other core BPL/DLLs in your path.)
Actually, it doesn't sound that inexplicable - it's probably caused by an exception occurring as the DataModule (or some form with db-aware components connected to it via properties) is being loaded into the IDE (see below). Have you tried checking that wherever your ZEOS .BPL files are located is on your system Path? Likewise any .BPLs they depend upon - see the "requires" clause in the .DPK file(s) for Zeos.
This sort of problem arises fairly frequently with flaky DB components, maybe more so than other types of component because db components more frequently involve linkages between datamodules and forms, e.g. when db-aware components on the forms are connected to others on the datamodule.
So, sometimes, whether this sort of problem shows up or not depends on the order in which the IDE will re-open them - try closing the project with only the dm open and then re-opening it. A bit of experimenting with which datamodules and forms are open in the IDE and in which order may help you pin down the problem. If/when you have a reproducible sequence of steps to provoke the problem, report it to the authors.
A fairly reliable way to determine whether the problem is being caused by an exception as a project loads is to run one instance of the IDE inside another. As long as the first ("outer") instance of the IDE has the debugger set to "Break on Language exceptions" it should be able to take you straight to the source of the exception (assuming it occurs, of course) when the project is loaded by the second instance. It may take a few goes to "catch it in the act" of course, but it is hugely satisfying when you manage to. Good luck!
Unlike MartynA I doubt this would be caused by an exception.
I would more likely expect such issues to be caused by windows path environment variable being too long.
Unfortunately still many component vendors and even some programs modify "windows path environment variable` to make their own files accessible by other programs.
And when windows path environment variable fails to provide sufficient information windows will try to find the files in default system directory which is C:\Windows\System32
So I would strongly advise checking the windows path environment variable to check its length.
The easiest way to do this is by simply starting the command prompt and typing in path directive or perhaps path >> D:\path.log to export the path environment variable information into a file for easier reading in case if it is long.
EDIT: BTW I just checked my path environment variable and I see that I will have to do some cleaning because it contains entries for both Delphi XE8 and Delphi XE 10 Seattle file locations even thou I have removed Delphi XE8 from my computer. Not to mention some entries from some programs that I have removed quite some time ago.

Pascal Delphi - Undeclared Identifier

I'm using the Synapse library in a Delphi project to do some networking.
When I try and use one of the Types that are defined in the external units, i.e: 'TTCPBlockSocket', it has the red underline and says "Undeclared Identifier 'TTCPBlockSocket'".
The files are all in the correct folders and the 'uses' statement can find them and shows no errors.
The strange thing is that I've had an identical setup in another project and there have been no errors in that project.
As a note: I can't install/edit the software/settings, so I can't add any fixes.
This is a well-known bug in Error Insight. It has existed since Error Insight was first introduced in Delphi 2005 or 2006, and still exists today in Delphi XE5.
It's caused by a different compiler being used for Error Insight, apparently, that doesn't have access to the same symbol set used by the Code Insight compiler (the one that helps you find symbols in the Code Editor) or the command-line compiler (the one used to actually compile your code for an application or package). It therefore only uses files that are actually referenced in the project (.dpr) file to locate symbols, and since the majority of files in the uses clause in your code aren't in the .dpr, it can't find them.
There are two fixes (one that is very easy, and one that works but is a pain in the backside):
(The easy one). Turn off Error Insight totally, in Tools->Options, the Editor Options section, Code Insight; just uncheck the box for Error Insight. I prefer this one because Error Insight doesn't work properly anyway, and it avoids the annoyance of having to use the other option every 10 minutes. This is the first thing I do when I install a new version of the IDE and see the red underlines.
(The pain way). Use Project->Add to project for every unit that contains one of the underlined symbols. This adds a reference to every unit to the project .dpr file, which causes it to increase in size drastically. It's a pain because you typically have to do that for every single unit (in my experience, including those that are part of the standard VCL/RTL) that hasn't already been added, and it very quickly becomes irritating. Error Insight doesn't tell you anything that a quick Ctrl+F9 won't anyway, IMO.

What does TDataModule.ClassGroup pseudo-property in Delphi XE2 really do?

I tried to copy and paste a component from one data module into another in Delphi XE2. The component was a Fast Report data source link component. The data module was brand new, just created that second, in XE2.
Someone else had the same problem and reported it on quality central as 106369 and same error message leading me to this mysterious DocWiki entry.
So data modules now have a framework affinity, and a designtime-only pseudo property, which according to the docs:
"Because the ClassGroup pseudo-property is used only by the IDE and is not a compiler-generated property (hence, 'pseudo-property'), ClassGroup is not documented in the compiler-generated Libraries Reference. The page you are reading is the documentation for ClassGroup."
So, the first time I even learn this exists is when it blocks me from copy and pasting components into my data module from an existing set of designtime building blocks that I didn't wish to rebuild from scratch.
Once I change the data module affinity, I can paste stuff into data modules without it bugging me. Thank goodness for Google-that-error or I'd be stuck.
If it is intended to help us write cross platform data modules, and yet it only affects the IDE, according to the documentation, that's inconsistent with the warning that you get when you play with this at designtime, here's the error you get if you change it:
EInvalidType : The following component(s) are not available in the specified
class group. This is likely to cause compile or runtime errors.
frxDBSet.TfrxDBDataset.
What I can't see is how that error message can be correct, and the documentation can also be correct.
The warnings seem to suggest compile, link, and runtime errors if this is set incorrectly. Curious minds who want to know what's really going on, want to know: What is this thing about and why did it get added to the data modules in XE2. I anticipate other people will stumble upon this weird feature, with the feeling that they've stepped in something like dinosaur droppings, and want to know what is up with this feature.
My best answer at this point is that a data module affinity for TPersistent which means, in XE2 lingo, that this data module doesn't want non-visual controls in it, that are VCL-specific. In a future version of Delphi, perhaps a similar marker would allow us to mark forms as being "clean of dependencies on the VCL or windows" too?
Update 1: The .PAS source code of your data module stores this pseudo-property in a way that looks a bit like a compiler directive, like this:
implementation
{%CLASSGROUP 'Vcl.Controls.TControl'}
I think it is pretty obviously what its intended use is for, and the documentation you link to is pretty extensive about that purpose.
It is meant to prevent VCL-only components from being placed on a FireMonkey-accessible DataModule, and vice versa.
Since TDataModule is initially framework-neutral, only framework-neutral components can be placed on it.
So obviously, your source DataModule has a different affinity than your new DataModule, which is why copy/paste does not work until you change the affinity of the new DataModule to match the affinity of the source DataModule.

Delphi XE2: EResNotFound exception "Resource "<mainform>" not found" raised on some target machines but not on others

I've been banging my head against this for the past two days and can't seem to make any progress...
Pretty much from one moment to the next, Delphi XE2 won't properly compile one of my projects any more. That is, it actually compiles without errors but at runtime I get resource not found errors for what is essentially the main "form" (it's actually a data module in this case). I have already reverted to older versions of the project from source control that I know were definitely working alright but to no avail. Judging by that it seems it must be something inside Delphi/the IDE itself rather than in the project source. However, I have also not been able to reproduce the issue with a simple test project nor with any other real-life projects... It only happens with this one.
Another strange thing is that when I look at the produced binary with XN Resource Explorer everything looks as it should: The form resource mentioned in the error message is actually there and intact...
At some point I was suspecting this might be caused by a bug in one of the experts I have installed in my IDE (e.g. Uwe's platform and OI experts and VersionInsightPlus, Andreas' IDEFixPack and DDevExtensions, GExperts) but even after disabling all these the problem persisted.
Unfortunately, I am unable to track down exactly when this started to happen as I had been working for some time without actually running the binary, fixing compiler warnings and errors for the x64-target, adjusting build events for updated third-party tools (localization and license protection) and such things...
Has anyone else ever seen anything like this happen? Any more ideas on how to pin this down?
Some more details about the project:
It is an addin for Outlook built using the Add-In-Express framework (i.e. a COM-DLL).
The "main form" is a TDataModule-descendant - we also inserted our own ancestor-class into the hierarchy, i.e. the "addin module" is not directly inheriting from TadxCOMAddInModule - the resources of the custom ancestor forms also appear to be present and intact in the output binary when checking with a resource viewer.
Built without runtime packages for the Win32 and Win64 platforms.
Let me know if you think I missed to mention any other potentially relevant details.
Update:
I have now transferred the sources in question onto a different machine. Interestingly, the DLL I compiled there did not exhibit the problem - on that machine that is... when I transfered it back to the original machine and I tried to call it, the error was back (to stress this: this was the exact same DLL producing a EResNotFound on one machine but not on the other. Of course, once I had discovered this, I also performed the reverse test and lo and behold, the DLL compiled on the original machine works without errors on the other machine...
Seems this might not be a Delphi problem after all... but what is it then?
Differences between the two machines:
Machine 1 (the one were the problem occurs): Windows 7 Ultimate English 64bit with Delphi XE2 Update 4
Machine 2: Windows 7 Professional German 32bit with Delphi XE2 Update 3
On a third machine that is almost identical to the first except that it doesn't have Delphi on it, DLLs produced by both machines work flawlessly.
I am a bit surprised to see your question here. :)
We faced a number of serious issues with recent Update 4 for Delphi XE2. Though we have never run into or been reported of the "resource not found" error, I think this update might be one of the causes. Have you installed it?
One more thing that comes to my mind is images that you use for your Office controls (command bar and ribbon). Probably they got broken somehow, the run-time code cannot load them and reports this error.
Anyway, as you understand, these are just my guesses, if you need our assistance with your office add-in please contact Add-in Express support service, we will try to help.
Update: Seems I was a bit too quick, drawing conclusions. Apparently the Sisulizer solution is also supposed to perform a fallback to the main resource block. I have now taken this issue to the product forum and will report back here, once this is resolved.
Alright, mystery solved at last:
I had turned off the option to "Copy all resources" in Sisulizer in an attempt to reduce the size of the produced resource DLLs and then had forgotten about it...
I hadn't fully realized the implications of the standard Delphi resource DLL approach to localization on which Sisulizer "piggybacks" - especially that it was an all-or-nothing deal: Our previous translation solution implemented a fallback-mechanism that would read any resources not found in the external resource DLL from the host binary instead. This does not appear to be the case with Sisulizer - at least not out of the box... thus, any resource that's not contained in the localized resource DLL does not exist as far as the application is concerned.
I also didn't realize that the mere existence of a file with the same base name as the main binary and an extension matching the current system's default locale (such as .EN or .DE) would automatically cause the VCL to load it...
The machines that did not exhibit the error either still had the older, larger (=complete) resource DLLs on them, or no resource DLLs at all.

How do I solve "Two different CRTLDLLs are loaded" when using packages in C++ Builder 2010?

We are trying to split up our monolithic EXE into a combination of an EXE and several packages. So far, we have one package that we're trying to use, and when running the EXE Codeguard shows the following error on startup:
CG Error
Two different CRTLDLLs are loaded. CG might report false errors
(C:\Windows\system32\CC32100MT.DLL)
(D:\Projects\Foo\Bar.bpl)
OK
I read this as two different runtime libraries being loaded - one, the correct one (CC32100MT.dll), one incorrect, which is the package we're trying to use.
Continuing to run the program shows odd errors, especially casting between classes or passing a pointer to a class as a parameter in a method that crosses the EXE/DLL boundary. Codeguard itself doesn't show any other errors at all though. Edit: This is now resolved, and wasn't related. The program appears to run correctly, but the warning Codeguard shows is still worrying.
How do we solve this?
Some more details
We've looked at as many things as we (the developer working on this and I) can collectively think of:
Each project is built using runtime packages. The EXE host lists Bar in its package list.
Each project is set to compile with dynamic RTL. However, changing this does not solve the problem.
The package is linked to the EXE via its BPI file, but linking via a LIB makes no difference either.
The EXE and BPL are compiled with the same project settings, where the same options exist for both types of project. We think, anyway :)
There is only one copy of the BPL and BPI on the system: it's definitely linking to the right one.
Examining the EXE and BPL with Depends and TDump show they are both using C:\Windows\system32\CC32100MT.DLL. They should both be using the one RTL.
Creating a new project (a plain VCL forms application) and linking to the BPL (via its BPI) works fine. Something in the process of adding all the files and LIBs that make our EXE contain the code it needs to changes this, but we haven't been able to figure out what.
The LIBs all either correspond to DLLs we use (flat C interface, usually look as though they were built with MSVC) or are simple projects with lots of related files, compiled to a lib for the purpose of linking into the EXE - these correspond roughly to the areas of the program we want to split to BPLs, by the way. There don't seem to be project options for the LIB projects that would affect RTL linking, unless we've missed them.
I have exhaustively hunted through Depends and looked at all RTL and CC32*.dll files the EXE and every single DLL references. All are identical: rtl140.bpl and CC32100MT.DLL. Fully qualified paths show they are the same files, too. Everything should be using the one same run-time library.
Edit: The final EXE is complex, built with several libs, several DLLs, etc. All these, when built with C++Builder, are built with the current version. Is it possible there's something in one of these DLLs or LIBs that could cause a problem? I don't know enough about how the RTL is linked in to be sure about where to look... my (naive?) assumption is that the linker would normally link in one set of RTL functions, but that of course doesn't seem to be happening... and I don't know how things change when using packages. Is it possible this error has always existed and Codeguard has not flagged it before, because we haven't used something dynamic like a package?
Perhaps another question is, Why would a package have its own RTL anyway, or what would make it count as 'a RTL DLL' to Codeguard?
We're stumped. Absolutely stumped. We've had other problems using BPLs (they seem to be surprisingly tricky things, especially using C++) but have managed to solve them all. This one we've had no luck at all and we'd really appreciate any insights :)
We're using C++Builder 2010 (as part of RAD Studio actually, but with little Delphi code apart from components.)
Edit: Started a bounty. I'd really like to solve this!
Edit 2: Thanks to David Dean for his help (marked as answered below.) Via email, he pointed out this issue was reproduced in a simple test case by someone else, and is logged in Embarcadero QC as report 86335. Currently there is no fix, but the warning does not appear to indicate a genuine problem (ie, it's probably a spurious error, and while it's a pity to have to click past the dialog when you run, hopefully there's nothing in the error to worry about.)
Since one of these is coming from a .bpl, did you try turning off "Build with runtime packages" in the project options?
We had a similar problem. We tracked it down to a (non VCL) .cbproj that was created without the "Multithreaded" option.
As far as I can tell, the only time you get chance to set this option is when you create a new .cbproj, it cannot be changed afterwards using the GUI. We ended up "hacking" the .cbproj to include the following:
<Multithreaded>true</Multithreaded>
To determine which dll is causing the issue, it should be the last dll loaded in the output window just before you see the CG message.
Did you check if you use _TCHAR as char. We had some similar problems with RAD Studio and we found a workaround using _TCHAR as char. As soon as one DLL or BPL Project is compiled with wchar_t, this code guard error appears.
We also figured out, that EXE projects can be compiled with TCHAR = wchar_t without any problem (the main function will be WIDE).
The settings does not affect the GUI being able to handle UNICODE.
A customer logged a similar case in our public bug tracking system and the bug has been identified and fixed in the latest release.

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