fsm | A simple finite state machine for Golang

It seems that your actual project has an old version of Netty somewhere on its classpath.

ByteBuf::writeMediumLE (and all the other LE-suffixed ByteBuf methods) were introduced in Netty 4.1.

If I understood question correctly, then it is necessary to apply some action by its state. If it is true, then we can use Factory pattern to get desired object which can execute some action. Mapping between state and action can be putted into HashTable.

So let's see an example of code. I will write via C#, but this code can be easily translated to Java because languages have many syntax similarities.

So we will have enum of statuses:

The DFT imposes a periodicity to the image in both the frequency and the spatial domain (some people disagree with this, but still agree that this view is a good way to explain just about everything that happens in the DFT...). So imagine that your input is not the Shepp-Logan phantom, but an infinite repetition of it. When manipulating the data in the frequency domain, you affect not just the one copy of the image you see, but all of them, and not always in intuitive ways.

One of the consequences is that neighboring copies of your image in the spatial domain rotate, but also expand and come into you image.

The simplest way to avoid this is to pad the image with zeros to double its size.

Correct Answer

The problem is that this is a bit extract. Chisel lets you do foo(bar) to extract the bit at index bar out of foo. The above code, as written, is a bit extract even though the user wants it to be a mistake.

Unfortunately, this is a known gotcha and it's not reasonable to error on this without false positives while still allowing users to use the () syntax for bit extracts.

Incorrect Original Answer

It's valid syntax per Scala rules. What's going on here is that the code is really two statements, but the indentation is confusing. It's equivalent to:

As per @Lundin's suggestion, I have put a watchpoint on lpuart_dma_rx_tc_isr_clback function pointer variable. It exposed the out of index bug in my code. The bug is inside while loop in main.c.

Here is one way to get rid of the compile errors:

The documentation on trait parameters only mentions trait parameters, not trait constructors:

Scala 3 allows traits to have parameters, just like classes have parameters.

It also links to the original SIP document for reference:

For more information, see Scala SIP 25.

In the SIP-25 – trait parameters, it says [bold emphasis mine]:

In the ClassDef of traits, we still do not allow secondary constructors.

However, this restriction, is not reflected in the Syntax Summary, which does not actually distinguish between classes and traits syntactically. So, the restriction is purely one of documentation, not syntax specification.

So, to answer your question:

Why?

Because your code is syntactically valid but semantically invalid, and ScalaMeta seems to not expect this specific kind of semantic invalidity.

And why is it after line 1, which seems perfectly fine and gets accepted when I remove the rest? Does "invariant failed" mean that it's a bug in the compiler? (Many other compilers in such cases add to the message an encouragement to report it.)

It's clearly not a bug in the compiler since the exception is not thrown in the compiler, it is thrown in ScalaMeta.

Main questions:

• Are secondary (or auxiliary – IIUC the two terms I've seen used apparently interchangeably mean the same) constructors allowed in traits?

No. SIP-25 clearly disallows them.

There is a problem with your reset logic. You should separate the reset clause from the rest of your logic; it should only be included in the if clause, and it should not be in the case statement.

Also, the case statement should be in an else clause:

The fsm model works in C by assigning function pointers to certain functions that have to process certain data. One good use for fsms is for parsing commandline arguments, for parsing captured output.... The function pointer is assigned to a preset starting function. The start function assigns the function pointer, which must be passed along, to the appropriate next function. And that decides the next function and so on. Here is a very simple implementation of a fsm: