I am trying to start making my own libraries avaialble as packages prior to compiling my Apps with these packages hence modularising my code. For years I've 'sort of' understood packages, breathing a sigh of relief when I load a component package and click on 'Install' and it does. I understand that the process of installing a component (or components) is via the creation of a BPL which is then registered with the IDE.
Where I begin to get lost is how to make files available so that I can compile with EITHER a package OR pre-compiled dcu's (like the third party vendors do) and without pointing my project at the source code all the time. I can create a package with the following settings:
where I've specified that all my output will go into 'c:\scratch\wow'. After a build I find TEST.BPL, TEST.DCP and lots of DUC's. Now, when I point another project at this folder to use the DCU's, I get a missing DFM error (one of the units is a form). Should I be manually copying needed DFM's into this output folder? The DPK knows about this form, so why do I not get the DFM copied for me? I presume that using TEST.BPL, that file contains everything, but I wish to work in the two modes. Of course I can get around this by including the source folder in my project search path to find the DFM but third party libraries seem to already have the DFM's in their output folder. Did they install them there using the installer?
Thanks
instead
As others say you could use post-build events to copy your DFM files into place. Other people use a one-time external batch file that copies the DFMs to the DCU folder.
Personally I see very little benefit to making packages for things which are not developed also as reusable components. I also see very little benefit in partitioning an existing application into packages, when you don't reasonably need to use the same subsection or package more than once, or at designtime.
Things I would put into packages:
Delphi visual and non-visual components.
Things which absolutely must be plugged in at runtime, or left out. For example, supposing I sell MetaWare Light and MetaWare Pro, and instead of using compiler IFDEFs to build a differnt binary, I preferred for some reason to simply not ship the ADVANCEDFEATURE.BPL with my systems.
Things to beware of with packages:
I have run into a lot of compiler bugs when combining packages with generics. I have also run into IDE crashes and lockups, in Delphi 2009, 2010, XE and XE2. (I believe XE3 is better)
You should learn a bit about BorlandMM.dll and shared memory management in the BPL world before you move to it. There are some subtleties.
Packages limits the ability of the linker to decide what to remove. In fact, it pretty much destroys it. Packages contain everything that is linked into them, and nothing publically accessible can be removed.
Once you've created a binary package and shipped it to even one customer, you have a pretty difficult to modify contract (this BPL contains a particular signature or application binary interface) you have to be careful in the future to never change them, or mix and match them. Beware of DLL hell, even among your own customers, and be prepared to use versioning on your packages. Just as delphi packages have a version suffix, I recommend you use version suffixes in your own packages right off the bat, and bump them whenever binary compatibility has changed.
Delphi handles build dependencies between packages about as well as could be hoped, which is less well than a single monolithic application. In applications that I have that make heavy use of packages, I find project groups that contain a bunch of packages that depend on each other are very difficult to manage and build quickly. In fact, I have experienced that both compiles and builds are slower and more frustrating than they would be in a singular 750Kline megaproject.
I really wonder if you're not that into the package area of Delphi (you breath a sigh of relief whenever a delphi component actually builds and installs without issue?) if you really want to move into the Packages World totally. By all means, you should experiment. But I wouldn't bet the farm on it yet. Learn some more first.
Yes, you should copy the .dfm to the directory with the compiled units (.dcus), if that is the only directory you want in your search path. The BPL will of course contain the .dfms, and you need a .dcp to be able to link a BPL with your app.
Third party tools must have put the .dfms together with the .dcus in the directory using their installer, indeed.
Instead of copying *.DFM manually you can use Post-Build Event (Project/Options/Build Event), ex:
copy “$(PROJECTDIR)\Unit1.DFM” “c:\Scratch\wow\Unit1.DFM”
I found a way to do this without moving .dfm files to the directory of .dcu files, so you can have a directory for .dcu files only one for .dcp files only and another for .bpl files only.
All you need to do is to create another directory on your good structure, as I do. The directory is called RES and in it should be placed all the resource files (.res files, not .dcr files) that are used by applications compiled using your packages (components). In the Delphi Library Path, you must include in addition to the DCU directory (you should already have) a directory named RES.
On your component (design time) do everything you want with the form (design it, put other components, etc). In the source code of the unit you replace {$R *.dfm} with {$R UnitName.dfm}. In doing so, save all and close the DPK. Now move the .dfm file (do not copy, move!) to the RES folder (the .dfm file is a resource file to the Delphi. The {$R} directive is proof!) and after that open the DPK again to understand what has changed.
First realize that you may not open the form (F12) from his unit, though no error was issued by Delphi about "DFM missing".
Now, do a Build on your package and then install it. Realized again? No errors displayed! This happened because you have indicated the location of .dfm file in the Delphi library search path (RES directory).
Done! You can use your component and dfm will be found when your component is included in an application.
Many of you can now say that this way I will not longer be able to visually edit a form in the component design time. Yes this is true, but if you think about it, why would I want to change so often a form into a component that, in practice, should only be used and slightly edited? Draw your own conclusions ;)
Related
When I open my project and I double click on a specific pas file in the Project Manager, bds.exe freezes and continues using 25% of the cpu. I have to kill the process through the Windows Task Manager. (1)
When I open my project and I press F12 on that exact same file, I see what I would have expected to see earlier, the contents of the pas file.
When I open my project and I compile it first, then double click on the file, everything is fine.
I'm trying to figure out how, what I assume to be a mismatched DCU file, snuck into my project and what the best way is to prevent a similar issue in the future. Can I force all DCU files to be rebuilt? Can I simply delete all dcu files and recompile or is that a dangerous thing to do? My DCU files are currently also stored in the same directory where I keep the pas and dfm files, that is a bit messy.
(1) our application also shows behaviour in production where it sometimes crashes while it continues to use a steady cpu usage or simply continues to work as expected but shows a steady cpu usage in the background. We have been unable to trigger it in a compiled version but see it popping up from time to time. We assume the dcu mismatch is at the source of this problem.
There are numerous issues in your question, some entirely unrelated, but the assumption that the problem is a "mismatched" DCU is unlikely to be correct (by which I presume you mean an "old" or otherwise incorrect DCU compiled in the past or with different source).
First your problems.
IDE Behaviour
The problem with the IDE locking up when double-clicking a unit in the Project Manager is unlikely to be anything to do with a "mismatched" DCU.
Do you have source files located on a network drive ? Is this unit such a file ? Is that network location available/valid ? i.e. is the path to the file using a network drive letter that is no longer mapped or otherwise not available ?
If there is no explicit path in the unit reference in the DPR, do you have network locations listed in your system, IDE or project PATH ?
Difficulty accessing file locations is the most likely explanation for the IDE appearing to lock up when trying to simply open a file.
As to why it should behave differently when using F12 rather than the Project Manager, unfortunately the Delphi IDE is notorious for using different mechanisms to achieve the same thing in different places so it isn't surprising that sometimes when one of these mechanisms breaks the others still work (and can give different results even when both work).
Runtime Behaviour of your App
If we work on the basis that you do indeed have a "mismatched" DCU then performing a full build of your project will resolve that mismatch, as long as you have the source for all the required DCU's and that the correct and appropriate source for each DCU is available.
However, even though the mismatch may be resolved, rebuilding may or may not fix the issue, depending on whether that issue remains in the source code for that unit itself when recompiled.
The simple fact of the DCU being "mismatched" cannot cause aberrant application behaviour. With the exception of OS or RTL bugs etc, if there are errors in the behaviour of an application then those errors will be the result of errors in the source code as compiled.
Simply recompiling source code containing an error will not remove that error.
As such, if there is such an error then far more information will be needed if anyone is to be able to give any assistance on that score (and this should be a separate question, once you have done some initial debugging and diagnostics yourself).
Runtime Packages
If you are using runtime packages then things get more complicated because with a runtime package, the DCU employed for any particular unit could be part of a package file. In that case, the DCU file on disk is produced when you compile the package itself but any project that uses that package will not use the DCU on disk but will instead use the version that has been compiled into the package.
So if you are using runtime packages then as well as rebuilding your project you need to also rebuild any and all runtime packages that may have changed.
Now, for your actual questions.
Q1: Can I Rebuild all The DCU's ?
Yes, of course. But see above w.r.t Runtime Packages, if your project uses them.
I would strongly recommend that you change your project settings to output DCU files to a specific location, separate from the source files.
For example, you could have a project specific DCU folder using a relative path. i.e. set your DCU output folder to something like ".\dcu" and create a dcu folder within the folder where your DPR is located.
For Delphi versions supporting multiple platforms and configurations it is best to include the environment variables for the platform and configuration in that path, so that you don't end up using units compiled for DEBUG in a RELEASE build.
e.g.
.\dcu\$(Platform)\$(Config)
or
.\$(Platform)\$(Config)\dcu
What Is Compiled in a Build ?
When you do a Build on a project (as distinct from a "Compile"), all units referenced by that project will be recompiled, with the exception of any VCL/RTL units (i.e. those provided with Delphi). Those get special treatment.
At a minimum, rebuilding a project will forcibly recompile all units explicitly listed in the DPR, but will also recompile all other units that are used by those units (or units that they use etc etc).
NOTE: DCU's With Missing Source
A unit will only be recompiled if the source can be located.
If you have a DCU and the source file is missing or cannot be located on the project, IDE or system path, then the compiler will simply assume that you want to use the existing DCU.
This is the case even with a full "Build".
3rd Party DCU's
It may seem obvious but you should also be careful that you don't delete DCU's that may be your only copy of any 3rd party libraries you may be using for which you do not have the source.
This is highly inadvisable, but I guess we mustn't rule out the possibility that you may be in this situation.
Q2: Should I Delete all the DCU's ?
In general, yes. As noted above, even a full build will be successful if you are missing the source code for a unit that is referenced, as long as there is a DCU (or required package, if using runtime packages) that can be found.
So the only way to be sure that you have the current source for all DCU's is to first delete the DCU's that any previous builds may have used.
This is of course much easier when you have a specific, explicit location in which all your project DCU's are output.
It's slightly more involved if you are using Runtime Packages, though if you are organising your DCU's sensibly then the only real complication is that you need to repeat the same exercise for all the projects involved, working through starting each of the runtime packages that are used and finishing with the projects that in turn use them.
Yes, you can rebuild all DCU files in your project;
In the project group window, right click on the project and select Build.
It is OK to delete all DCUs in your project, but not necessary (or desirable in case you make a mistake...).
Note that this only builds DCUs explicitly in you project (as shown in your project tree) not any implicit ones imported as a result of your uses clauses.
Three things may be going on that have not been adressed in other answers.
Note that I only have experience with Delphi XE2 and Seattle 10, but they may apply to your version.
Delphi can be slow when switching from form to source view, especially if you have many components on your form. In migrating from XE2 to 10, we noticed an improvement here. We are talking seconds here, this does not seem to be your issue.
Delphi can be notoriously slow when switching between projects. After a switch the IDE can take a very long time (20-30 seconds) to respond. You cannot type anything; code completion takes a long time; initiating a project search with Alt-S-D waits a long time, then fails. In migrating from XE2 to 10, we noticed a large deterioration here.
Conditional compilation. If you have IFDEFs in your code compiling stuff for one project but not for another, your IDE can hang completely, and there's nothing else you can do then killing BDS.EXE. This happens in Delphi Seattle 10 if you switch projects and accidentally Compile instead of Build.
You may experience variations of these.
Installing components under Delphi XE3 is a nightmare.
First I need to add source files to
Tools -> Options -> Library
then I need to find a normal package and compile it
finally I need to find design time package and install it.
This is just quite tedious and error prone. Is there a nicer way to install components?
I have found Delphi Package Installer. Unfortunately it doesn't support Delphi XE3 or above.
I have heard that there is something similar which produces exe packages that install themselves (something like Inno Setup) but I can't find such thing.
No. The steps above are required.
First, adding the file path to Tools->Options->Delphi Options->Library Path is so the compiler knows where to find the files to compile them. (Actually, it's not required - you can eliminate this step by making sure that the .dpk files are in the same folder as the .pas files, and that all .pas file names are listed in the includes section in the .dpk. If the .pas files are in a different location, you'll need to either use relative paths in the .dpk (eg., MyComponents in '..\Source\MyComponents.pas') or add the location of the .pas files to Project->Options->Delphi Compiler->Search Path.)
The next step (finding the "normal package") is in order to build the runtime package. It's required, because the design-time package (next step) requires the code that's in that package in order to function in the Form Designer. It's also needed when you decide to build your application with runtime packages, if you use the third-party components and want to distribute the runtime package for it.
The separate design-time package (the third step) is required because designtime code can only be used at design-time; there's nothing that can be distributed with an application if it's built with runtime packages and the package build in step 2 is one of them.
This has been the way components are installed since around Delphi 3 or so, and the requirement to separate out designtime code into it's own package started being advised in Delphi 5 and enforced in Delphi 6 (when they relocated much of the IDE designtime support into their own separate packages and stopped distributing the source for them).
There really are no other options, unless the vendor supplies pre-build designtime and runtime packages for you, or supplies an installer that will do all of the above steps. (Most don't.) But if you update your Delphi version, you'd still have to go through the steps above.
What about the built-in component installer? It is part of Delphi XE, XE2 and XE3 and a description can be found here (I wrote it). It will even install components in C++Builder. You can instal into an existing package or into a new one, which it will create for you.
I would say that the best way to install components is to use your build manager (for example FinalBuilder) and add each component to a manager-project file which sets the necessary paths, builds the DPK files, and 'installs' the component in the IDE by making a registry entry. That way you have a documented procedure which allows you reliably to set up or repair your complete, tested, Delphi development environment. You can simply re-run the project when a component has been updated and tested. It is also quite easy to tweak an existing project to handle a new Delphi version.
The big disadvantage of a vendor-supplied installer is that all the ones I have seen simply overwrite the previous version on updates. I prefer to control the install myself, so that I have previous component source versions archived and available for comparison, in case testing reveals a problem with an upgrade. The 'one-click install' sounds fine, until a minor component upgrade suddenly causes your application to stop working.
Take a look at "Lazy Delphi Builder". It was created to simplify build/installation of many components at once. It resolves packages dependencies automatically. Free to use.
Link to some old tutorial
I'm trying to make a package for a custom component I made. It's based on several libraries, including Graphics32, GraphicEx and CCR.Exif.
I created a Package project, wrote the unit including its Register procedure, added some extra references Delphi notified me about to the requires section (including dbrtl.dcp, inet.dcp, soaprtl.dcp, vclimg.dcp, xmlrtl.dcp and dclGraphicEx140.dcp) and added many units to the contains section to avoid warnings about it happening implicitly. The project compiles and can be installed and used on my own machine without issues. However, when I want to install it on another machine, the troubles begin. In the end, I had to copy about all DCUs from all 3rd party components I used, plus both the DCP and BPL from GraphicEx, which I had to install even.
Supplying a lot of files is a bummer, yet surmountable, but having to install other packages as well is a no go. I could get rid of that DCP and BPL by putting even more units in the contains section, but that resulted in error messages on my own machine where GraphicEx is actually installed. This is confusing to me, because with Graphics32 nothing like that occurs...
Anyway, how do I keep my distribution to a minimum and avoid such situations? I want other developers on my team to be able to use the package without worrying about what I used to build it. For a start, can't all the 3rd party units be compiled into my own DCU?
What you experienced is an usual thing to the ones who write components. The distribution is always like that. Packages do not carry other packages, insted they reference them. It´s in their nature.
In order to overcome such a situation I always treat my components in the same way I would if they were a product to sell: I build a setup wizard that distributes and registers everything the package needs.
In my case InnoSetup works very well (http://www.jrsoftware.org/isinfo.php).
Summary
Haven't use Delphi for a while, but, did develop my custom visual controls (Last version I work was Delphi 6).
There are 2 issues when dealing with packages dependencies. One is installing at the Delphi enviroment, making controls appear on the component palette, plus, component editors & property editors.
And another when distributing the compiled packages into customers machines.
It also depends, on which version on Delphi you are running.
Design Time
When developing a custom package, there is a tab for package options, that indicates the destination folders.
The manuals usually tell the developers to leave those textboxes empty. That sometimes works, sometimes doesn't. I explicity write each folder path, in the respective textbox.
There is a textbox path for the ".dcp" files, other for the ".dcu", and so on.
If you have visual controls and stuff like property editors or component editors, its better to split the code in 2 packages ("Runtime" & "Designtime").
I usually put the delphi (packages) projects outside the delphi installation folder.
Run Time
Usually, the quick way is to put the "*.bpl" ".dcp" files in the Windows (32) / system folder, or similar "DLL" windows folder.
Packages folder structure source code suggestion
Managing packages can be difficult. I don't know how much the installation process has changed with Embarcadero, and the newer versions of Delphi. The following chart,is an example on how organize the source code. Hope it helps.
[-]--+--c:
.....|
.....+--[-]--+--software
.............|
.............+--[+]-----java
.............|
.............+--[+]-----php
.............|
.............+--[-]--+--delphi (not the delphi folder in program files)
.....................|
.....................+--[+]-----apps (source code for delphi programs)
.....................|
.....................+--[+]-----other
.....................|
.....................+--[-]--+--packages (all delphi packages source code here)
.............................|
.............................+--[+]-----lib (a single package for non visual controls, libraries)
.............................|
.............................+--[+]-----tools (package pair for non visual tcomponent descendants)
.............................|
.............................+--[+]-----json (example)
.............................|
.............................+--[+]-----xml (example)
.............................|
.............................+--[-]--+--mycontrols (folder custom visual controls)
.............................|.......|
.............................|.......+--[-]--+--delphi40 (folder for delphi40 version of "mycontrols")
.............................|.......|.......|
.............................|.......|.......+----------dsgvclctrls40.dpk (design-time package "mycontrols")
.............................|.......|.......|
.............................|.......|.......+----------runvclctrls40.dpk (run-time package "mycontrols")
.............................|.......|.......|
.............................|.......|.......+--[+]--+--demos (individual example for each "mycontrol")
.............................|.......|.......|
.............................|.......|.......+--[+]--+--design ("*.pas" component editors destination folder)
.............................|.......|.......|
.............................|.......|.......+--[+]--+--sources ("*.pas" source code destination folder)
.............................|.......|.......|
.............................|.......|.......+--[+]--+--bin ("*.dcu" destination folder)
.............................|.......|........
.............................|.......+--[+]--+--delphi50 (folder for delphi50 version of "mycontrols")
.............................|.......|........
.............................|.......+--[+]--+--delphi60 (folder for delphi60 version of "mycontrols")
.............................|.......|........
.............................|.......+--[+]--+--delphi70 (folder for delphi70 version of "mycontrols")
.............................|................
.............................+--[-]-----etc...
Cheers.
Thijs, you simply cannot do that with only a package. The target developer will require almost everything you added to the package. But there is an alternate way of doing what you want: Build a DLL with all the components/libraries you are using in your own component and wrap all those external components/libraries into some code you will export from the DLL. Then build your component without using the external components directly but the DLL you've built. You cannot in you component "use" any unit of the other external components/Libraries. You have to build a new unit with all the datatypes and required declaration for anything you export from your DLL. All this is perfectly working but will quickly becomes very complex for a large number of external components or libraries.
I think AlexSC has the best answer, but I think there might be an alternative if you ansolutely must have a custom component that has no dependencies.
I ran into the Delphi dependency frustrations a little while back trying to create an in-house component for our developers. My suggestion:
Uninstall all dependencies your component uses
In your component package, remove the above dcp from the requires section from your package.
Copy the source files of your dependencies to your components
When you distribute the component, you'll have to distibute it with the code of the required dependecies
You'll run into issues if you want to use the dependcies separately since Delphi won't allow you to have duplicate unit names in installed packages.
Also, the reason you don't want to use DCUs is the fact that the DCUs are compiled for a specific platform and compiler. So unless you are sure that all devolpers are on the same platform ad using the same version of Delphi, dependency code needs to be recompiled.
Again, AlexSC has the best answer and InnoStudio is a great little tool.
The company I work for develops a system in Delphi, that contains dozens of exe modules, and each of them is identical to a certain degree if it comes to source code. Sadly, nobody has ever cared about using libraries to put the shared code in. This means that each time there is a bug fix to do in the code all these modules share, a programmer has to make corrections in all of them separately! It always takes so much time...
I decided to find a method to put the shared code into libraries. I considered DLLs and BPLs. In this case BPLs seemed much more programmer-friendly and much less troublesome, especially that the code is used only in our software and only in Delphi.
I put all the code shared by all the exe modules into BPLs and everything seems fine, but there are certain things I don't understand and would be grateful if you explained them to me.
What I expected after dividing the code into BPLs was that it would be enough to deploy exe files with the BPLs I created. But it turned out that they need an rtl100.bpl and vcl100.bpl as well. Why is it so? I want to deploy exes and my BPLs only. I don't want to provide end users with a whole bunch of libraries supplied by Borland and third party companies :). I want them to be compiled within exes as they used to be compiled before. Is it possible to do that?
What I did so far was:
I put all shared pas units to BPLs. Each BPL contains units belonging to the same category so it is clear for programmers what code to expect in a given BPL.
Each BPL is a "runtime and designtime" library.
Each BPL is "rebuilt explicitly".
The two latter are default project settings for BPLs.
And if it comes to the exe projects:
I deleted all units that I had earlier put to BPLs.
I installed my BPLs from the Tools->Install package menu in BDS 2006.
In my exe project settings I checked the option "build with runtime packages" and I listed all my BPL packages in the edit box below (only my packages, as I cleared all other ones that appeared there).
This is all I did. The exe projects compile properly, but I have no access to the source code of BPLs (I can't navigate into that code from my exe projects), even though all BPLs are stored together with their source code files. Why? It seems strange to me.
I always tend to write lengthy descriptions - sorry for that :). I will appreciate your help. I just need a few words of explanation to the points I mentioned: deploying exe with my BPLs only, the correctness of what I did as a whole, and the inability to navigate into BPL source codes. Thank you very much in advance!
Thank you all for the discussion. Some said the approach I chose was not a good idea. Our software consists of more than 100 modules (most of them being something like drivers for different devices). Most of them share the same code - in most cases classes. The problem is that those classes are not always put into separate, standalone pas units. I mean that the shared code is often put into units containing code specific to a module. This means that when you fix a bug in a shared class, it is not enough to copy the pas unit it is defined in into all software modules and recompile them. Unfortunately, you have to copy and paste the fixed pieces of code into each module, one by one, into a proper unit and class. This takes a lot of time and this is what I would like to eliminate, choosing a correct approach - please help me.
I thought that using BPLs would be a good solution, but it has some downsides, as some of you mentioned. The worst problem is that if each EXE needs several BPLs, our technical support people will have to know which EXE needs which BPLs and then provide end users with proper files. As long as we don't have a software updater, this will be a great deal for both our technicians and end user. They will certainly get lost and angry :-/.
Also compatibility issues may happen - if one BPL is shared by many EXEs, a modification of one BPL can bee good for one EXE and bad for some other ones - #Warren P.
What should I do then to make bug fixes quicker to make in so many projects? I think of one of the following approaches. If you have better ideas, please let me know.
Put shared code into separate and standalone pas units, so when there is a bug fix in one of them, it is enough to copy it to all projects (overwrite the old files) and recompile all of them.
This solution seems to be OK as far as a rearly modified code is concrened. But we also have pas units with general use functions and procedures, which often undrego modifications - we add new functions there whenever necessary, but in single projects. So imagine that you write a new function in one of the 100 modules and put it into its general use unit. After a month or two you modify a different module and you think you need the same function you wrote 2 months ago. You have to find the module (it's difficult if you don't remember which one it was) and copy the function to your code. And obviously - the general use units become completely different in each module as long as they are stored in each project separately. And then, if there is a bug fix to do... the whole story repeats.
Create BPLs for all the shared code, but link them into EXEs, so that EXEs are standalone.
For me it seems the best solution now, but there are several cons. If I do a bug fix in a BPL, each programmer will have to update the BPLs on their computer. What if they forget? But still, I think it is a minor problem. If we take care of informing each other about changes, everything should be fine.
#CodeInChaos: I don't know if I understood you properly. Do you mean sharing pas files between projects? How to do that? We store source codes in SVN. This means that we would have to store shared code in a separate folder and make all projects search for that code there, right? And download from the SVN a project and all folders it is dependent on...
Please, help me choose a good solution. I just don't want the company to lose much more time and money than necessary on bugfixes just because of a stupid approach to software development.
Thank you very much.
Even though this question has an accepted answer I'm going to take a stab at it.
The title asks how to divide a project into bpls but the real question appears to be:
"What's the best way to share code between projects?"
There are a few ways to do this:
Shared units
Dlls
BPLs
Regardless of which direction you go you will likely need to restructure your projects. From your description it sounds like each project is developed in relative isolation. Code is shared using copy/paste, which quickly gets out of sync and result in a lot of duplicated effort. So lets examine each of the techniques for sharing code.
Shared units
This is the most straightforward approach. You create a shared location and place code you would like to reuse among your projects into this location. The units are statically linked into your projects so you don't need to worry about deploying extra dependencies along with the main executables. Statically linked units are by far the easiest to troubleshoot and debug.
The compiler needs to be able to find your shared units. There are 4 ways to tell the compiler where to look.
Add them to the project - SHIFT+F11 - Adds a reference to the unit into the project files (dpr, dproj). The IDE will normally use relative paths if the unit is located under the same directory tree as the project files, otherwise it will use absolute paths, which can be problematic if developer machines aren't configured identically.
The project's Search Path - CTRL+SHIFT+F11 Delphi Compiler > Search path - Add a directory and the compiler will look there to find units mentioned in the uses clause of any unit in the project. Its best to use relative paths if you can. You can also use environment variables: $(MyPath)
Global Search Path - Tools > Options > Environment Options > Delphi Options > Library - Win32 > Library Path - Any paths listed here are available to all projects on a machine. This is machine dependant
Command line - If you build from a script or build automation tool you can set the search path using the dcc32's -U switch or msbuild's /property:UnitSearchPath= switch.
Options 1 and 2 will be the most useful.
As far as your SVN repository goes you have a few options for organizing the projects and shared units. The simplest would be to place all projects under single trunk along with the shared units:
Projects
trunk
ProjectA
ProjectB
ProjectC
Library (shared units)
If for some reason the above structure isn't possible you could try this alternative:
ProjectA
trunk
Library (branch of main library)
ProjectB
trunk
Library (branch of main library)
ProjectC
trunk
Library (branch of main library)
Library
trunk (main library)
In this configuration changes made to each project's library folder would not be immediately available to the other projects. Each project would need to synchronize changes with the main Library project on a regular basis. A side effect of this is that changes that break other projects will be delayed until the other projects are synchronized. Whether you consider this a good or bad thing depends. On the one hand bugs are easier and cheaper to fix when the code they involve is still fresh in the developer's mind. On the other hand if you don't practice unit testing (which I highly recommend you do) or the code is very fragile or you just have developers prone to making reckless changes you may want to control how frequently those changes get pushed into other projects.
Dlls
Dlls allow you to share code by linking to it at runtime. They expose functions that can be called from a main executable or another dll.
While dlls are always linked at runtime you decide whether they are loaded at application startup or only when needed. Loading at startup is called static loading and in Delphi is accomplished using the external directive. The vast majority of the rtl/vcl classes that wrap system api calls use static loading. Dynamic loading lets to delay the loading of a dll until it is required. This uses the WinAPI functions LoadLibrary and GetProcAddress. A corresponding call to FreeLibrary will unload a dll.
Unfortunately standard dlls limit what kind of datatypes can be passed. If you need to access a dll from non-Delphi projects you will need to limit yourself to using c style data types. If you will only be using a dll with Delphi projects you can safely use Delphi strings and dynamic arrays as well if you use the SharedMem unit in the dll and any projects that use it.
You can safely use object's within the dll without problems but if you want to pass objects between the dll and the application you'll need to extract the object's data and pass it as primitive types and reassemble it into an object on the other end. This is called (de)serialization or marshalling and there are much easier ways to do this than rolling your own.
COM (Component Object Model) is well supported in Delphi but it has a bit of a learning curve. Consuming COM objects is pretty straightforward but designing one will take time if you're not familiar with COM. COM has the advantage that it is language neutral and is supported in the majority of languages targeting the Windows platform (including languages targeting the .NET framework).
Bpls
Bpls (also called simply "packages") are specially formatted dlls that make working with objects a lot easier. Like standard dlls they are linked at runtime and can be statically or dynamically loaded. They are easier to learn and use than COM dlls and provide more seamles integration into your projects than COM. Packages are composed of two parts: the bpl and the dcp. The dcp is like the dcu files generated when you compile a normal unit file except it contains a whole bunch of units in it. Using a class that is compiled in a bpl is as simple as adding the dcp to the project's package list then adding a unit to a uses clause of one of the project's units.
When you deploy the app you'll need to install the bpl as well. As other's have noted you have to include the rtl package at a minimum and most likely the vcl package if you use any forms. There is a way around deploying Borland supplied bpls with your projects. You can create a "mini" rtl package that contains only the units your project need. The difficultly is in determining which units to include.
Summary
From the description you've given creating a library of shared unit files to statically link against may be the most expedient route. I would also suggest trying out a program called Simian. It will help you track down duplicate code in your code base for inclusion in your shared library. It doesn't directly support pascal but it does a decent enough job using the plain text parser with a little tweaking of its configuration.
Also I can't stress enough the value of unit testing. Especially if you're moving toward shared libraries. A suite of well written unit tests run on a frequent basis will give you instant feedback when a developer changes a class and it breaks an unrelated project.
Imagine you have a project with an EXE and two different BPL modules, and somewhere in that codebase, there's a line that says if MyObject is TStringList then DoSomething;. The is operator works by examining the object's class metadata, stored in the VMT, and then following a chain of VMTs through the ClassParent pointer, to see if any of them match the class reference (also a VMT pointer) for TStringList. In order to make sure that this will work correctly, there needs to be one single VMT for TStringList that's the same throughout your entire program, no matter how many BPLs it's divided up into, which means it has to be in its own package. That's why system runtimes like rtl*.bpl and vcl*.bpl are necessary, and there's not much you can do about that. It's part of the price of using BPLs.
As for not being able to debug, you need to make sure that the BPLs are built with debug info enabled and that the debugger knows how to find the folder where the DCP (the file containing the debug info for the BPL) is located. And you won't be able to trace into system BPLs, because debug-enabled DCPs weren't shipped with your version. They were added pretty recently, I think in XE but it might have been in D2010.
Why can't I browse my source code? Is there a way to fix this?
You can not browse the source code of the units included in the packages because they are neither in your project, your library or search path.
The way I solve this is adding the directories to the project search path. This way the compiler does not know about those files (and does not try to recompile them) but the IDE let's you browse their content and debug into them.
"In my exe project settings I checked the option "build with runtime packages"
That is why you cannot deploy without the BPL's etc - this option is confusing for a lot of developers -"build with runtime packages" means that you will need the bpl's present at runtime. Uncheck that option and the packages will be linked into your exe at compileTime. (Your exe will g-r-o-w in size.) The idea behind the "build with runtime packages" is to keep the size of exe's down and allow several apps to share common bpl's because they are NOT linked into the exe # compileTime - that's the upside. The downside you are now experiencing - you must distribute your bpl's with your exe.
I need to know if is there any option to compile a delphi project only if the source or any used unit, package etc has been changed.
If this is not possible, second alternative : Is there any option to generate exactly the same binary compiling two times the same project.
Thanks.
Edit: The usage is for a hash based WebUpdate.
A Delphi "compile" will compile only changed units. But as said, unit have data so the compiler can check which needs updating and which not. And the executable can change because the build process can rearrange the exe. Your web updates should not use a file hash, it should use version information to decide what to update and what not. That's the way installers check which files should be replaced.
Delphi compiles only changed units on a compile, and compiles all units regardless of change-status on a build.
Exe's are never the same, on a binary level. Just built a project twice, renamed the exe's to have a txt extension and compared them with Beyond Compare: it shows differences.
One (hard) solution: Make your exes using a Makefile! A makefile allows you to say "this exe is made from those files, using those commands". Make will only run "those commands" if at least one of the files you list as making up your exe is newer then your exe.
The hard part in this is setting up the list of files that make up your exe: You can easily get the list of files listed in the DPR/DPROJ, but you'll also need to identify all the linked resources ($R), all the included files ($INCLUDE), all the files that are implictelly compiled by Delphi because they're used in the "uses" clauses and are found on the Library Path.
Generating a Makefile for the general case is very difficult, but for one particular project it might work. For example you might consider your file dependent on only the files listed in the DPR files and then make sure you add all the relevant files to the DPR.