Due to popular demand here is a small "Install package HOW-TO".
We're going to look at installing database components, which weren't installed by default in old Lazarus versions. They are still not present in the minimal IDE, but are there in the normal IDE. Though database components are nowadays present in Lazarus by default, the concepts of finding and installing packages can still be nicely illustrated.
We are going to look for and install the components to connect to a database (server) and to retrieve data from this database?
Well, let's have a look to see if we can find some of this stuff.
Files installed with Lazarus
Under Linux Lazarus gets installed by default in /usr/bin/lazarus, on Mac OS X Lazarus is installed in /usr/local/share/lazarus, and with Windows the installer gives you a choice where to install the files, as long as there are no spaces in its path. On my Windows PC Lazarus got installed in G:/Lazarus. Whatever the base path of your Lazarus installation is, there you will find some subdirectories. In this case the first subdirectory looks rather promising as it is called components.
As you can see there are a few subdirectories there, which remind us of databases. One sees an Interbase, a mysql, a sqlite and a sqldb directory. The first three contain database connection components and TDataset descendants for the respective databases. The last one, sqldb, is more generic, as it consists of TSQLQuery (a TDataset) and TSQLTransaction which are used for all types of databases and a T??Connection to make the connection to the database. In this article we will install the sqldb package together with the connection for Interbase.
Adding packages using the IDE
Adding known packages
Open "Package -> Install/Uninstall Packages". The list on the left shows already installed packages or packages marked for installation (which have a green plus sign in their icon). The list to the right shows packages that you can install. Simply double-click on a package in either list to move them to the other - and mark them for installation/uninstall.
Finally, click "Save and Rebuild" to rebuild the IDE and the packages.
You can also compile and install packages the IDE knows nothing about. See below.
Adding new packages
To install a new package one goes to "Components -> Open Package File (.lpk)". In our example scenario, in the following dialog you navigate to /usr/share/lazarus/components/sqldb or the corresponding directory under OS X or Windows and choose the sqldblaz.lpk file. If everything works out as planned you will see the Package Manager. The Package Manager shows a treeview with the files in the package and the required packages.
If you don't want to install the component into the IDE, e.g. because it is a non graphical component, press Compile. Otherwise you should press Use >> and Install. Next we get a warning about Lazarus only supporting static linked libraries and the question if you want to rebuild Lazarus. Just press Yes and sit back. Lazarus will be rebuilt, and depending on your configuration restarted.
If everything went well you'll see a new tab called SQLdb. This tab will contain two components: a TSQLConnection and a TSQLQuery. What we need next is a Connection component. Once again go to Components -> Open Package File and navigate to /usr/share/lazarus/components/sqldb/interbase. Open the ibconnectionlaz.lpk file and again press Compile and Install and Yes. :)
Next time Lazarus is started the SQLdb tab also contains a component TIBConnection.
Compile an IDE with packages at command line
There is no command line tool yet to configure and setup the IDE config files to add/remove packages. You must set up the packages with an IDE, copy the configs and adapt the path. See here for details: Install IDE packages without the IDE. But the rest can be done on the command line:
First build a normal IDE and LCL
make clean all
Then compile the IDE with packages
This will build the packages that the config files say need to be installed, then the IDE and finally link them all together:
The --build-ide parameter can take some options, for example -gh for heaptrc or '-gh -gt'.
If you have any questions, go to the lazarus forum or post it to the Lazarus mailing list.