golang: how to define sequence of steps

php Xiaobian Banana will introduce you how to define a step sequence in Golang. In software development, it is often necessary to perform a series of operations or tasks in a certain order. Golang provides a concise and efficient way to define and execute sequences of steps. By using goroutines and channels, we can execute multiple steps concurrently and ensure that they are executed in the specified order. In this article, we'll explore how to define a sequence of steps and demonstrate its usage using example code. Whether you are a Golang beginner or an experienced developer, this article will provide you with valuable information and practical tips. Let’s take a look!

Question content

I want to write a protocol test. My current idea is to define a sequence of steps. Each step contains a trigger and an expectation - for example triggering msga and expecting msgb.

type series struct {
  steps []step
}

What I don't like about this is that series is unclear: I have to create the slices in order and then hope it never gets messed up and rely on that, or sort which then has the implementation sort function, which is completely unnecessary.

What would be a good design to formally define series and make it explicit in this way?

My best idea right now is to create a map with an int index:

type Series struct {
   Steps map[int]Step
}

series := Series{
   Steps: map[int]Step{
     0: Step{},
     1: Step{},
     2: Step{},
     ...
   }
}

Another option might be to build yourself a linked list. go is not implemented (as far as I know). It felt weird having to build one myself for this. But such a solution also slightly loses explicit functionality: basically, you always have to browse the linked list to get the entire sequence (e.g. "what is step 4").

Workaround

In addition to using a map, you can still use slices and use keying Compound text:

var steps = []step{
    0: step{},
    1: step{},
    ...
}

Specification: Compound text has detailed instructions:

compositelit  = literaltype literalvalue .
literaltype   = structtype | arraytype | "[" "..." "]" elementtype |
                slicetype | maptype | typename [ typeargs ] .
literalvalue  = "{" [ elementlist [ "," ] ] "}" .
elementlist   = keyedelement { "," keyedelement } .
keyedelement  = [ key ":" ] element .
key           = fieldname | expression | literalvalue .
fieldname     = identifier .
element       = expression | literalvalue .

As you can see, keyedelement may contain an optional key ":" part.

...The key is interpreted as the field name of structure literals, the index of array and slice literals , and the key of map literals.

Note that you can mix keyed and "non-keyed" elements, and they don't have to be consecutive. Also, if a key is missing from the slice literal, the index will be the previous index 1.

type step struct{}

var steps = []*step{
    0:       &step{},
    1:       &step{},
    &step{}, // implicit index: 2
    5:       &step{},
}
fmt.println(steps)

Output of the above (try it on go playground):

[0x559008 0x559008 0x559008 <nil> <nil> 0x559008]

Their keys may also be "out of order", meaning this is also valid:

var steps = []*Step{
    5:       &Step{},
    0:       &Step{},
    1:       &Step{},
    &Step{}, // implicit index: 2
}

This output is the same. Try it on go playground.

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