IT Sky Consulting GmbH
Usually we think of rounding as a way of approximately expressing numbers with many decimal places by numbers with fewer decimal places. Regular readers of this blog have already encountered, that this concept can be extended and generalized, as is mentioned in the article about Geometric and Harmonic Rounding and Residue Class Rounding or Rounding …
„Rounding to Rational Numbers“ weiterlesen
Some commonly used languages have been quite well designed or at least would have been considered so at the time when they appeared. Even if they have their weaknesses, they should be good for some purposes. Now beauty of programming languages is highly subjective. So I do not claim any universal truth to this. But …
„Accident Languages“ weiterlesen
UUIDs have proven useful in many circumstances. We have basically two main variants: The UUID is calculated as a combination of the Ethernet-MAC-address, the timestamp and a counter. The UUID is calculated using a good random number generator While variant 1 provides for a good uniqueness, there are some issues with it. Today we use …
The functions sqrt and sometimes even cbrt are commonly available, but it is nice to see how they can be calculated. There are several approaches, but the most popular ones are Newton’s method and an algorithmic formulation of how roots are taken manually, for those old enough to still have learned it in school. Earlier …
„How to calculate Square Roots and Cubic Roots“ weiterlesen
When we write APIs, that have parameters or as return values, it is a good idea to consider relying on immutable objects only. This applies also when collections are involved directly or indirectly as content of the classes that occur as return values or parameters. Changing what is given through the API in either direction …
„Guava-Collections in Java-APIs“ weiterlesen
Scala Days had a tenth anniversary in 2019. It is an annual conference about Scala, which I like to visit, when possible. There is some confusion as to what is meant: Where this the 9th, 10th or 11th Scala Days? Where the first Scala Days 9, 10 or 11 years ago? The truth is, that …
In many programming languages we are urged to define methods hashCode, equals and toString. They are named like this in Java and in many JVM languages or they use similar names. Some languages like Perl and Scala provide decent mechanisms for the language to figure these out itself, which we do most of the time …
„hashCode, equals and toString“ weiterlesen
This may come as a surprise, but attackers can assume that software is running in one of the common languages with their standard library. This calculates the hashcode of a string in a predictable way. For that reason it is possible, to create a large number of entries that result in strings having the same …
„Can hashCodes impose a security risk?“ weiterlesen
Quite often I hear the idea, that one team should specify a software system and get the development done by another team. Only good documentation is needed and good API contracts and beyond that, no further cooperation and communication is needed. Often a complete set of unit tests is recommended as a way or as …
„Unit Tests as Specifications“ weiterlesen
Microservices are a Hype, but they have their pros and cons. Sometimes people say, that this is the magic tool to solve all problems. They hear it on conference talks, read it in the internet or even in books. It is not the first time and it won’t be the last time that we hear …