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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for October 4th, 2018

To help understanding combinations of boolean operators: Truth table – Wikipedia

Posted by jpluimers on 2018/10/04

Most software developers know they exist, but some (including me) find them hard to visualise, especially for combinations of operators, or for less common operators: the Truth table – Wikipedia.

The common operators that everyone seems to understand are these:

  • logical true
  • logical false
  • logical negation
  • logical and
  • logical or
  • logical xor

It becomes harder with a series of combinations, for instance series of and (not ...) and (not ...) and (not ...) – not to be confused with nand, similarly or (not ...) or (not ...) or (not ...) – not to be confused with nor, which both can be transformed according to the De Morgan’s laws – Wikipedia:

In set theory and Boolean algebra, these are written formally as

{\displaystyle {\begin{aligned}{\overline {A\cup B}}&={\overline {A}}\cap {\overline {B}},\\{\overline {A\cap B}}&={\overline {A}}\cup {\overline {B}},\end{aligned}}}

Using truth tables

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Posted in Algorithms, Conference Topics, Conferences, Development, Event, Software Development | 2 Comments »

What’s the point of having abstract classes in Delphi? 

Posted by jpluimers on 2018/10/04

There was an interesting thread a while ago: [WayBack] What’s the point of having abstract classes in Delphi? – Agustin Ortu – Google+

The answer is none (the documentation warns you against it – see Constructing instance of abstract class –  the compiler doesn’t), so Stefan Glienke submitted this bug: RSP-10235: No warning for .Create on class declared as TClass = class abstract

This post is a reminder to myself to see if any progress has been made by the compiler engineers.

–jeroen

Posted in Delphi, Development, Software Development | 9 Comments »

Raspberry Pi Power Limitations – Raspberry Pi Stack Exchange

Posted by jpluimers on 2018/10/04

There are very many, often contradictory, claims about the power requirements and limitations of the Pi. What are the exact requirements?

has a very elaborate answer at [WayBackRaspberry Pi Power Limitations – Raspberry Pi Stack Exchange covering all non-zero models.

I’ve archived some of the links it points to:

And some links on how to power a Raspberry Pi when you only have a 12V power source:

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Posted in Development, Hardware Development, Raspberry Pi | Leave a Comment »

 
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