Posts in Castle
As described in FSMs are needed Finit State Machines are great and needed – even tough no (main) programming
language has syntax support for it. But there are other (computer) language that (more-or-less) support the
corresponding State pattern.
By example plantUML –very populair by mature developers– has a syntax to draw them.
What can we learn from them? That is the topic of this post, before we define the Castle syntax.
Finit State Machines (FSMs) are great to model behaviour and control flow. Probably it is one of the most used design patterns; some developers are not even aware they are using it (when using the State pattern). And non of the well-known system-programming-languages does support it directly – it’s a shame;-)
This leads to sub-optimal, often hard to maintain code. In Castle, you can use define a FSM directly. Let’s see why that is essential.
In Grammar is code we have mentioned that many compiler-compilers reuse the Yacc invention “actions”. And we hinted already that Castle prefers an alternative.
Let’s see why the old concept is outdated … And what is easier to use.
In Compiler Compiler we have seen that we can define a grammar within a Castle-program. And we have argued that each grammars-rule can be considered as a function.
In this post, we look into de details of how this works. And will confirm grammars is code …
In Castle you can define a grammar directly in your code. The compiler will translate them into functions, using the build-in (PEG) compiler-compiler – at least that was it called back in the days of YACC.
How does one use that? And why should you?