proposal: Go 2: watch variable changes

[xingzhao0401]

Go Programming Experience

Intermediate

Other Languages Experience

c/c++

Related Idea

• Has this idea, or one like it, been proposed before?
• Does this affect error handling?
• Is this about generics?
• Is this change backward compatible? Breaking the Go 1 compatibility guarantee is a large cost and requires a large benefit

Has this idea, or one like it, been proposed before?

No

Does this affect error handling?

No

Is this about generics?

No

Proposal

Recently debugging a logic more complex data processing related code,the large amount of data and complex structure make it difficult to debug breakpoints
If possible,propose to add a new feature:
Add a new keyword 'watch'(or '@','#','$'...), when the variable value specified by 'watch' changes, a code segment is automatically executed,work with the breakpoints or 'runtime.Stack' to locate specific code locations where particular data appears.
This can facilitate debugging of some logically complex code, or list outliers in advance when writing code, and find problems in time during writing.
for example:

type Data struct{
	Age int
}
func F1(d *Data){
	d.Age = -1
}
func F2(d *Data){
	d.Age = 201
}
func aaa () error {
	data := Data{}
	watch data.Age {
		if data.Age < 0 {
		    fmt.Println(stack())
		    return errors.New(fmt.Sprint("unexpected value",data.Age))
		}
		if data.Age == 201 {
		    fmt.Println(stack())
		}
		....
	}
	data.Age = 2
	......
	data.F1(&data)
	......
	data.F2(&data)
	......
	return nil
}

for frequent data changes, this new feature may only be suitable for code development、BUG debugging and other scenarios;
but it seems to handle errors pretty well, although I like 'if err != nil' very much
for example：

func bbb() (interface{}, error){
	var err error
	watch err {
		if err != nil {
			fmt.Println(err)
			return nil,err
		}
	}

	err = func1()
        ...
	err = func2()
	...

	return 111,err
}

Language Spec Changes

No response

Informal Change

No response

Is this change backward compatible?

Yes

Orthogonality: How does this change interact or overlap with existing features?

No response

Would this change make Go easier or harder to learn, and why?

No response

Cost Description

No response

Changes to Go ToolChain

No response

Performance Costs

No response

Prototype

No response

[gabyhelp]

Similar Issues

• Proposal: Go 2: the "watch" statement for easier error handling & more #40821

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[dominikh]

This seems like functionality that belongs in a debugger, not the language. In fact, Delve already supports watchpoints.

[xingzhao0401]

This seems like functionality that belongs in a debugger, not the language. In fact, Delve already supports watchpoints.

Thinks