Early in my career, I was studying the code of an application written for the Apple II in preparation for developing something similar on the PC and would often ask questions of the original programmer. Most of the time, I'd get valuable information about the purpose of a routine or why something was done a particular way. But every once in a while, when pressed for an explanation, the programmer would think for a minute, then simply utter, "For Historical Purposes" and walk away chuckling.
This time of year in the United States is marked by a major holiday, Thanksgiving, the last Thursday of November. It is during this time that ad campaigns, religious organizations, and families everywhere tend to step up their recognition of everything they're thankful for. As a software developer, I'd like to hook into this theme and highlight features of programming tools I use that make my life better--most notably, Delphi--and create my own "thankfulness" list.
I like to keep all my computers upgraded with the latest versions of their respective operating systems. This goes for Mac and Android devices as well as all machines running Windows--even my virtual machines get the most recent upgrades whenever I use them. My development systems all use Windows but only one has been upgraded to Windows 11--the rest are still on Windows 10.
Nearly two years ago, Idera acquired apilayer, a collection of various cloud-based APIs. Idera being Embarcadero's parent company (and Embarcadero being the publisher of my favorite development tool, Delphi), I was interested to see what this was all about and looked at the handful of APIs available. One caught my eye and I made a note to come back and check it out more when the time was right.
The Delphi Debate series continues with another topic that has been discussed back and forth for ages. This time, instead of a procedure or function in the RTL, we are talking about three reserved words: the with, goto, and label statements which pre-date Delphi--they are part of the core Pascal language itself!
As a Delphi MVP, I was surveyed on my stance of the use of
FreeAndNil. In that questionnaire was included a question about the use of
Assigned(). Really? Is that debated as well? I couldn't find anything on the internet debating this except for an old discussion on StackOverflow. I use this function frequently and as I looked more deeply at what it does, I'm even more confident of its use.
When freeing an object in Delphi, simply calling its
Free method calls the object's
destructor and releases the memory allocated to the instance of the object. But it doesn't change the address of the referencing variable which, therefore, still points to the place in memory where the object existed. The released memory can be quickly reused by other objects or resources and if you try to access the object again without re-creating it, you could get an Access Violation or some other error or worse yet, unpredictable behavior.