Quick one I hope - I'm just about to delve into a Delphi 5 legacy app that makes calls to a DLL (also written in D5), passing a string which the DLL can modify if required.
I have the code to both the DLL and the app. Pasted right at the top of the DLL source is a remark about using ShareMem, and it needing to be the first line in the uses clause of the project etc.
If I was porting this whole thing to D2007, is there a better (or more modern) way of getting a Delphi app to share string data with a Delphi DLL? Does the D5 ShareMem stuff still apply to Delphi 2007 applications (with FastMM etc)? I haven't even had a bash at recompiling the whole thing yet - just wondered if this bit was going to be a problem and if there was an alternative/recommended way of doing this?
FWIW, the DLL is totally first party (it's only used by this particular app - so recompiling it under D2007 as well wouldn't be a problem).
To use the FastMM included with D2007, use SimpleShareMem as the 1st unit in both your application and the DLL projects.
Or download the full FastMM4 from SourceForge, set the Flags in FastMM4Options.Inc (ShareMM, ShareMMIfLibrary, AttemptToUseSharedMM) and put FastMM4 as the 1st unit in both the application and the DLL projects.
Use only a FastMM4. FastMM4 is a great memory manager and automatically includes a ShareMem like solution! FastMM4 is compatible with D5 and up!
The reason you need sharemem is that the reference counting on ansistrings breaks when passed to a dll. One solution is :-
If you are able to restrict your strings to shortstring then you can dispense with sharemem. I have written some two dozen dlls, mostly drivers for hardware and I have not had to use sharemem once.
Related
Is it good idea to put Forms that have complete functionality in dll.
And main app will invoke dll function that returns form object.
The accepted way to do this in Delphi is to use packages rather than DLLs.
Packages are essentially DLLs but with Delphi specific capabilities that allow VCL objects to be used across package boundaries.
Trying to do this with DLLs will lead to a variety of problems that packages deal with. One downside of packages is that all modules must be compiled with the same version of Delphi. But if you are wanting to share objects across module boundaries then you would face the same restriction if you used DLLs.
The Delphi documentation has extensive coverage of packages.
Having said all that, I would add that if you can put all your code into a single module (.exe or .dll) then it does make life a lot simpler.
Adding to the answers about using packages:
Packages can only be used if both, the main app and all dlls (plugins) are written in Delphi and are written using the same version of Delphi
DLLs can be written in any programming language that can create them and can be used by any program regardless of the programming language
So, using dlls rather than packages does make sense.
Regarding the actual question: Yes, it is possible to put forms into dlls and they usually work fine. Just make sure that you do not pass them around because they are only valid objects within the context of the dll. You will experience the odd problem with forms losing focus or coming up behind other forms. This can usually be fixed by passing a window handle from the main executable to the dll which is then used as the parent for the form.
Also note: TObject of your dll is different from TObject of your application. The same applies to other commonly used classes and variables like (Forms.)Application.
I have done it and it was a pain in the lower back but it was not impossible. The main program was written in Visual Basic 6, some modules were written in Delphi 6, others were written in Delphi 7 and Delphi 2007.
Conclusion: If you are sure you will never use something different than Delphi for your app and for your dlls (plugins) and are willing to always recompile everything when you switch Delphi versions, you should use packages. Otherwise it might be better to use regular dlls. (And are you sure you will always be the only person writing these dlls? Maybe at some time there will be a 3rd party developer for one of the dlls who does not own the Delphi version he needs.)
IMO this is sometimes a very good idea and the only way to go - for the reasons others have mentioned, I'm not a fan of packages, and am very comfortable with DLL's. I am currently adding functionality to an app written in Delphi 5 using Delphi XE - it was either use DLL's or write in D5 - of course I opted for the former: D5 app calls DLL's written in XE that contain all the latest and greatest features. (The first projects I did in Delphi were done via the old Borland Paradox - Paradox app invoked DLL's written in Delphi 1!)
But, I don't send the form or module from the DLL back to the main app - I just send the DLL module a structure containing what it needs to know to do its work, and when it's done and the DLL's form closes, it cleans up and then and returns a numerical code or structure back to caller indicating success, failure etc ( old fashioned but very effective).
Passing the form instance from the DLL back to your main app across the DLL threshhold can be problematic - note #dummzeuch's excellent answer above with some good tips on how to negotiate some of those problems should you decide that is your only solution.
+1 for everything that David Heffernan says.
Strategically, you really only need to implement forms (or other functionality) in external files if you're implementing a plug in system.
If you're going to allow plugins to be authored in any language, then DLL's are the only way to go.
If your plugin system will be restricted to developers with the same version of Delphi (same team perhaps?) then go with BPL's. The additional drawback of Delphi packages, from my perspective, is the need to deploy the VCL BPL's with your app, which are always more Mb than a single compiled module.
If on the other hand you want to write a modular system, you can still do that by implementing loose coupling & "plugin" techniques within your code and still compile to a single module.
If you put a form in a normal dll the form won't be able to intercept the TAB or arrow keys. I have been told that this is due to the OnKeyDown not be passed through.
I have been using FastMM4 version 4.92 in my Delphi 6 Pro application smoothly. I now want to use it in a package I created (BPL). I tried putting the units in the Contains section and then moving them to the top of the list but I still get the error from FastMM4 complaining that it is not the first unit to be initialized. To fix this I want to put FastMM4 in the Requires section but I can't find a DCP file for FastMM4 anywhere (runtime library). Does anyone know how to make this happen?
Probably, the reason you've got this error is that you should include FastMM4 unit not in your package, but in project where you are testing(using) your newcreated package(ofcourse on the first place in 'uses' section).
Did you set UseRuntimePackages in the FastMM4Options.inc file? Otherwise you could try to use ShareMem and the BorlndMM.dll replacement that comes with FastMM. Although ShareMem is designed for DLLs, its use should route all memory management routines to those in the BorlndMM.dll, allowing both the standard packages and yours to use FastMM code.
Up until now I am developing using Delphi 7. In order to pass f.e. TStringLists to my DLL's I use the FastShareMem unit as first unit in every program and dll I develop.
If I should migrate to Delphi-2010, Does FastShareMem still necessary ?
Thanks for any insight you may provide.
Short answer: No, SimpleShareMem comes with Delphi 2010
Long answer: Yes, Delphi still has its own memory manager and memory claimed from one memory manager (exe) can not be returned to another (dll). But since Delphi 2006 Delphi comes with a new memory manager called FastMM which can do the same as FastShareMem and also does not require any extra dlls to be distributed. You need to use a unit called SimpleShareMem. FastMM also has other nice features you might want to check out. FastMM is also available for Delphi 7 BTW.
You don't need to use any of those tricks if you compile with runtime packages, since the memory manager is then shared. It also comes with the advantage of sharing the same types. No more TFont can not be assigned to TFont problems. Of course this does mean you have to distribute the runtime packages.
No, use SimpleShareMem instead as first unit in your Application and DLL.
Delphi 2007 and above include now FastMM as default memory manager, which used by SimpleShareMem and no need to distribute any DLL with your application.
It is possible to work with a Delphi 5 project in the Delphi 2009 IDE by referencing the Delphi 5 version of dcc32?
If so are there any issues to watch out for concerning the way that project settings (search paths, conditional defines etc.) are implemented in 2009?
Edit: Just to clarify I am also upgrading the project to Unicode but will still need to debug and run releases in the old configuration
It depends on what you're trying to accomplish and what limitations you are willing to accept.
As far as I know, you can't use the Delphi 2009 IDE to maintain Delphi 5 projects directly. For example, even if you stick to functionality that's common between the two, some properties that are not supported in Delphi 5 are written to your DFMs, causing an error at run time.
I've maintained projects and library code that were written in Delphi 2005/2006/2007 that was also being used in Delphi 6/7. I usually edited and debugged these using the latest IDE. I had separate project files for each target version and made sure they all used the same memory manager. Finally, I had an automated build process and unit tests that would strip incompatible properties out of the DFMs (my own DFM Scrubber), make sure all of the targets always compile and run unit tests, which are also recompiled for each target.
All in all, it's more effort and I wouldn't recommend it unless you have a specific requirement to do so.
No. That said, it is still Delphi, and assuming you have source or D2009 versions of any custom components it can be modified to compile in Delphi 2009. The layout of the VCL has changed quite a bit since D5, so expect to have to modify your uses clauses and probably rewrite some small chunks here and there, but it is doable.
You either port your code to Delphi 2009/2010 level (Unicode), or you may as well not install the product.
I suggest you open the project and see where it fails, close the project (without saving anything), find the component versions you need and install them, and once the project opens up in design mode (all components are installed) you can start porting.
Read the Unicode Delphi migration (porting) information available at the website.
Ask your self each time you see PChar, and Char, if it needs to be PAnsiChar, or AnsiChar instead? If you are reading bytes from a disk, a com port, or a network connection, you will need to change from Char to AnsiChar, from PChar to PAnsiChar, otherwise, you might just leave the Char and PChar as they are and they will become Unicode. Always be aware that Char is not a Byte, anymore.
You also must replace explicit references to narrow Win32 API calls with versions without the A (ansi) suffix. Example: CreateFileA might need to become just CreateFile.
W
In the company that i work, we develop all the GUI in C#, but the application kernel is mainly developed in Delphi 5 (for historical reasons), with a lot of components made in COM+. Related to this very specific sort of application a I two questions:
Experienced guys in Delphi and/or COM, do you have any workrounds to work with the buggy TLB interface ?
Some of the bugs are: IDE crashing during edition of a large TLB, lost of methods IDs, TLB corruption, etc.
Here, we haven't found any good solution. Actually we tried do upgrade do the new 2007 version. But the new IDE TLB interface has the same bugs that we found before.
How do you control TLBs versions ? The TLB file is in a binary format and conflict resolutions are very hard to do. We tried to do it exporting the interfaces descriptions to IDL and commiting into CVS, but we didn't found any good way to generate TLBs from IDL using Delphi. Additionaly, the MIDL tool provided by Microsoft, didn't parse correctly the IDL files that we exported from delphi.
I think you should have a good look at Delphi 2009.
Delphi 2009 has changes to the COM support, including a text-based replacement for the binary TLB files.
You can read more on Chris Bensen's blog.
In the distant past (before I started working for CodeGear) I gave up on the odd Delphi-ized IDL language that the IDE presented, and wrote my own IDL and compiled it using MS midl. This largely worked; the only catch, IIRC, was making sure dispids (id attribute) were correct on automation interfaces (dispinterfaces) for property getters & setters - there was some invariant that tlibimp expected but midl didn't guarantee.
However, now that Delphi 2009 uses a safe subset of midl syntax, and includes a compiler for this midl in the box and integrated into the IDE, these problems should be a thing of the past.
We have also just installed Delphi 2009 and it does seem to have improved the support for Typelibraries. However I have worked with COM and type libraries for quite some time and here are my general gotchas that I have found over the years. I would agree its pretty buggy and is all the way up to Delphi 2006 (our version prior to using 2009).
Always have every file writeable before opening. This may sound obvious, but when working with source control sometimes we forget to do this and try to remove readonly flag after opening a file - Delphi cant deal with this. Ensure tlb is writable before opening.
If editing a standalone typelibrary you MUST have a project open. For some reason if you open a type library on its own it will not save. Create a blank project and then open your typelibrary. For some reason this allows the type library to be saved.
If your type library is used by an application or COM+ ensure that application is shut down or COM+ disabled before opening the type library. Any open apps will prevent the type library from being saved.
However I think your best solution is probably an upgrade. You get Unicode support too.
Using Delphi 2009 has greatly taken much of the pain out of huge TLB files, and conversion of our existing objects was painless, but our com objects don't use any third party libraries.
We will be migrating our gui applications over once the library vendors release supported versions.
Same experience with the TLB interface here: we simply stopped using it.
We work with several separate IDL files (hand-build) for different parts of our framework, making use of the #include construct to include them into the IDL of the actual application, then generate the single tlb using MIDL and tlibimp it. If the application has no IDL of it's own, pre-compiled version of the different framework TLB files are available.
Whenever the framework enters a new version, a script is run to re-generate the GUIDS on all necessary interfaces in the IDL files.
This has served us well for many years, and for us to move over the new Delphi 2009 IDL/TLB toolset will have to be not only integrated into the IDE, but also versatile when it comes to automated builds and whatnot. Can't wait to get my hands dirty with some experiments!