Delphi Programming Tips & Tricks

Atomic operations are ones which can be executed on otherwise-unprotected shared data as a single indivisible step, where no other thread will be able to compromise the consistency of either that shared data or the operation itself. In other words, even for operation logic consisting of multiple, compound operations—steps—being atomic means that all those steps will run as an unbreakable whole on the shared data, and multiple threads will not be able to interfere with each other. Most fundamental atomic operations are actually implemented on the hardware level, and rely on specific CPU instructions to ensure atomicity, but some can also be implemented in higher level code with the help of those atomic primitives. Because hardware support is needed for the most fundamental primitives, atomic operations will be limited to simple data types commonly up to a size of a pointer. Support for atomic operations for larger data sizes—double pointers or even more—is hardware-dependent, and Del...

 It is a CodeRage season.  Join me next Tuesday, December 2, at 20:00 GMT for my session "Multi-threaded programming: two problems, you now have" and find out how to avoid some common problems when writing multi-threaded code in Delphi applications. Register now!

Anyone who has ever debugged a 64-bit application in Delphi, especially one that involves multiple threads, has probably experienced disconnected session issues, or the IDE not showing watch values, or simply getting non-responsive in the middle of a debugging session. The new 64-bit IDE and its LLDB-based debugger provide a solution to such problems. You may no longer have to sprinkle your code with logging code that is otherwise not needed; nor will you have to waste hours trying to catch some error, only for Delphi to die on you when you are two lines of code away from discovering the problem. However, it is not all that peachy. Namely, LLDB has its own quirks. First of all, it is dog slow. It is slow when evaluating breakpoints, it is slow when handling exceptions (even ignored ones), it is slow when it stops at a breakpoint and shows local variable values. The more powerful computer you have, the better the experience will be. While there is still plenty of room for improveme...

Delphi's procedural types fall into three categories: standalone procedures and functions, methods, and anonymous methods. The variables that can store those types are all different, both in their memory size and their nature. Further differences between various procedural types come from the number of parameters they have and their types, as well as whether they return some result—whether they are functions. Those differences have an impact on how they are invoked, but not on their storage—the variables and their memory layout. Two procedural types will be compatible with each other, if they are of the same category, have the same calling convention, have the same number of parameters (including the return value or lack of it). and those parameters and return value are of the same types and declared in the same order. The declared parameter names can be different, and don't affect this compatibility. Declaring any of those procedural types has some common parts: a type iden...

The construction of reference-counted object instances, which have automatic memory management, is a recurring topic. The main problem with such instances is that they need to be assigned to an interface reference (explicit or implicit) to have a properly initialized reference counting mechanism and a properly managed lifetime. There are many different coding patterns and scenarios around the construction and assignment of such instances. The simplest scenario is having an explicit interface reference to which we will assign the newly constructed object; in some, the compiler will lend us a hand and insert the appropriate code behind the scenes; and in some, it will do the opposite, due to either some compiler bugs or an ambiguity in the code which cannot be automatically resolved by the compiler. In previous blog posts, I have previously covered some such scenarios which needed special attention from developers to avoid bugs: Hello Old New Leaky Friend Inline Variables Type I...

The Delphi 12.3 update has just been released. The most exciting part of this release is the long-awaited 64-bit IDE. Now, this is only an Initial Release of the IDE, and it is not yet a full replacement for the 32-bit IDE and its functionality. The main advantage of the 64-bit IDE is that the available memory is no longer constrained by the 32-bit address space, and the upper limit is now the available system memory. The more you have, the more you can use. This is a great news for all developers with large projects, where the 32-bit IDE would easily hit the memory wall. To start with, the 64-bit IDE only supports the 64-bit Windows platform. The primary purpose of such a release with only partial functionality is to allow all component developers to update their design-time packages, and prepare them to support the 64-bit IDE. And to do that, you only need the 64-bit Windows platform anyway. For all other platforms, there is no immediate advantage of using a 64-bit IDE. As we all...