README
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sflag
Cmdline arg parser using struct syntax
Documentation
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Overview ¶
Package sflag is a commandline arguments parser using struct syntax
Usage
var opt = struct {
Usage string "sflags demonstrator"
SomeFile string "contains the something | /dev/null"
IQ int "do not inflate | 42"
GDP float64 "in Vietnamese Dong | 42000000000000000000000000.0"
Age int64 "in milliseconds since epoch | 42000000000000"
SomeCommand string "! is command that might contain pipe char ! 'yes | head'"
Verbose bool "Bool flags require use of an equals sign syntax (i.e. \"var=value\") to be unambiguous | false"
OutData string " must be writable | /an/output/file"
Args []string
Foo *int // sflag will ignore both member and tag since it is initialized to non-nil pointer
Bar *int "bar" // sflag will not look for default value in this tag, since it will be a nil pointer
Baz_ int "Set by --baz, not --Baz | 42"
ignoreMe string // sflag will ignore low-case members
}{}
func Example() {
foo := 1;
opt.Foo = &foo // sflag will ignore this variable since it is a non-nil pointer
sflag.Parse(&opt)
fmt.Println("SomeFile=", opt.SomeFile)
fmt.Println("Age=", opt.Age)
fmt.Println("IQ=", opt.IQ)
fmt.Println("GDP=", opt.GDP)
fmt.Println("SomeCommand=", opt.SomeCommand)
fmt.Println("Verbose=", opt.Verbose)
if opt.Bar != nil {
fmt.Println("Bar=", *opt.Bar)
} else {
fmt.Println("Bar was not set")
}
fmt.Println("baz=", opt.Baz_)
for ii, aa := range opt.Args {
fmt.Println("arg num", ii, ":", aa)
}
}
Package sflag is a flag package variant that is 100% DRY, free of fugly pointer syntax and uses clean struct syntax.
Implementation makes use of reflection and struct tags, in manner similar to previously published flag variants.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Parse ¶
func Parse(ss interface{})
Parse iterates through the members of the struct. Notes:
Members are set up for std flag package to do the actual parsing, using type obtained via reflection and info from struct tag for usage and default setting. Normally, the rightmost pipe char in the tag is used to delineate between Description (on left) and Default value (on right). (You can override delineator to the first char of the tag (after eliminating leading whitespace) if such char is not alphabetic). Fields with no tag or whitespace-only tags are ignored. Non-nil pointer fields are ignored. Nil pointer fields will be left nil if that flag is not set on commandline (and the tag is not parsed for a default value). Flags starting with lowercase letter require that the coresponding member ends in single underscore. Provide string member Usage initialized to brief program description. Parse will append member descriptions to that string. Provide []string member Args if you want to want to retrieve unconsumed flags. Initialize []string member Args to the string array you want to parse instead of os.Args[1:].
func Parse2 ¶
func Parse2(ss interface{})
Parse2 is identical to Parse, except panics if there is both (1) a boolean flag and (2) a standalone true/false argument. It reminds you to use "--Foo=true" syntax (instead of "--Foo true" which would terminate the stdlib's flag processing for bool flag Foo, which is considered set by its presence alone). The downside of using this func is that unrelated presence of true/false results in progam panic.
Types ¶
This section is empty.
Source Files
Directories