For the BPL package, I personally understand is: is a package, and Dll,exe similar, put the code in the package to save it.
First, talk about how to create a BPL package
1. Open the Delphi IDE (Delphi7 for example)-->file-->close all (off all)
-->file-->new-->other--> in the New Item tab (new)-->package-->ok;
2, click OK, Delphi helped us to create a number of packages needed for the basic things, such as,
At this point we can add the source code that has already been written (click on the Add button to be added) or create a new unit in the File menu.
3. Click the option button
Design Period package (Designtime only)-used to install the control in the Delphi IDE environment and to create a special property editor for the control. Design period packages allow the inclusion of controls, properties, and control editors, and so on,
Run-time package (runtime only)-provides support for VCL and library functions when running a program, which is similar to the standard dynamic-link library.
Design and run-time packages (Designtime and runtime): Designed and run
Click OK after selecting the appropriate type according to the actual needs
4. Click the Delphi IDE save button to save the project (PUBMETHOD.DPK)-click Compile-no error will be generated in the Delphi installation path under the BPL folder PUBMETHOD.BPL; PUBMETHOD.DCP;
You can also modify the output path to direct the output file to the specified directory, the creation of this BPL is done, so easy bar
Second, the following talk about how to use BPL
The use of BPL is also very simple, in the need to use the BPL of the project as long as the BPL introduced in it.
The cells in the BPL package are then referenced in the unit to be used.
It's simple.
Delphi BPL Pack Learning