while print flag , the placeholder if need but not set.

[jokemanfire]

What type of PR is this?

• feature

What this PR does / why we need it:

Change like this:

OPTIONS:
--bar value
--help, -h show help

OPTIONS:
--bar string
--help, -h show help

Special notes for your reviewer:

This is a feature that I like because having a placeholder as a value is not very helpful for users. And it's a bit troublesome to specifically set up a placeholder.

Testing

I have run the help_test.go , but it can't pass . Because I consider if we should add a switch, otherwise it will affect the compatibility of the previous version

Release Notes

Change flag show placeholder to show flag initial type.

[jokemanfire]

@Skeeve Thank you, could you please take a look

[Skeeve]

@Skeeve Thank you, could you please take a look

I can, but I cannot approve.

[avorima]

It's currently possible to get the following help output with the Usage field:

Usage: "string"
Output:
   --bar value  string

Usage: "`string`"
Output:
   --bar string  string

I think either one of those cases could be changed to overwrite the placeholder without setting a usage.

[abitrolly]

This whole section is questionable.

cli/flag.go

Lines 300 to 310 in 7fc43e7

	// enforce DocGeneration interface on flags to avoid reflection
	df, ok := f.(DocGenerationFlag)
	if !ok {
	return ""
	}
	placeholder, usage := unquoteUsage(df.GetUsage())
	needsPlaceholder := df.TakesValue()
	if needsPlaceholder && placeholder == "" {
	placeholder = defaultPlaceholder
	}

The unquoteUsage() function parses flag value type from the usage (!) string (#333). I am +1 on dropping this workaround if this PR works.

[avorima]

I didn't know this was a workaround to get stdlib flag functionality. Might I add two points to consider:

• If the interface method were Type() string it would allow inter-op with pflag's Value interface.
• reflect.Type.Name() works for strings, numbers and bools but returns the empty string for slices and maps. I think for those the default value should still apply.

[jokemanfire]

Thanks all @avorima @abitrolly @Skeeve . I will make a summary based on your suggestions and explain my ideas ,

1. I would like to keep that method https://github.com/urfave/cli/issues/333 , because somebody may want to custom flag type by themself .
2. If reflect.Type.Name() is not enough for get all base type , I will try to use other method.

my next step will be:

1. Improve this code to ensure that all basic types can be displayed, and ensure that custom priority is > the default flag type (like string., bool , etc )priority.
2. Fix CI
3. Fix doc

[jokemanfire]

• If the interface method were Type() string it would allow inter-op with pflag's Value interface.

Sorry , but I didn't understand this tips , because my English is not very good.

[Skeeve]

0cb6639#diff-f09230a06a76ff761bbdcc9b788aa057cc5caa463f1bd68e67b14422938622d4R110

I think the "[]" is of no additional value and should be omitted.

1. Brackets have a well known meaning in usage texts. They are confusing here
2. Slice flags are no different from non-slice flags. There is no special parameter syntax for them

I think you should avoid the "[]" marker.