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When you still need use the singleton pattern?

The singleton pattern has come a long way since early 1990x. The programmer interview question "Write a singleton" in 1995 has evolved to "Write a lazy initialized singleton" in 2000x, and finished by "Why we do not use a singleton?" in 2010x.

Indeed, the unproved using of multiple singletons should be considered as antipattern. However, we still need singletons in some cases.

static_cast vs dynamic_cast: undefined behavior

Do not use static_cast when you cast from a basic class to a derived one. This may lead to undefined behavior. To handle the polymorphism, a virtual inheritance or a multiple inheritance case always use dynamic_cast instead.

The following short example shows the undefined behavior cases. This works with GCC, VC and online C++ shells:

Qt Test limitations and workarounds

Pros and cons

Why use Qt Test for unit testing and TDD (test-driven development)?

  • small testing framework (about 6K lines of source code);
  • seamless integration with QtCreator development environment;
  • full support of Qt framework including classes/types and signal/slots;
  • simple to start and use.

However, there are some drawbacks, too.

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