Interactive help
Interactive help is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
Demonstrate any interactive (or command line) help offered by the language implementation.
This can be for exploring features or syntax, or perhaps a simple message on where to find more information.
Go
The 'go doc' command line tool shows documentation for either a package or a symbol within a package.
For example, here we list the exported functions and types in the 'strings' package in the standard library:
$ go doc strings
package strings // import "strings"
Package strings implements simple functions to manipulate UTF-8 encoded
strings.
For information about UTF-8 strings in Go, see
https://blog.golang.org/strings.
func Compare(a, b string) int
func Contains(s, substr string) bool
func ContainsAny(s, chars string) bool
func ContainsRune(s string, r rune) bool
func Count(s, substr string) int
func EqualFold(s, t string) bool
func Fields(s string) []string
func FieldsFunc(s string, f func(rune) bool) []string
func HasPrefix(s, prefix string) bool
func HasSuffix(s, suffix string) bool
func Index(s, substr string) int
func IndexAny(s, chars string) int
func IndexByte(s string, c byte) int
func IndexFunc(s string, f func(rune) bool) int
func IndexRune(s string, r rune) int
func Join(a []string, sep string) string
func LastIndex(s, substr string) int
func LastIndexAny(s, chars string) int
func LastIndexByte(s string, c byte) int
func LastIndexFunc(s string, f func(rune) bool) int
func Map(mapping func(rune) rune, s string) string
func Repeat(s string, count int) string
func Replace(s, old, new string, n int) string
func Split(s, sep string) []string
func SplitAfter(s, sep string) []string
func SplitAfterN(s, sep string, n int) []string
func SplitN(s, sep string, n int) []string
func Title(s string) string
func ToLower(s string) string
func ToLowerSpecial(c unicode.SpecialCase, s string) string
func ToTitle(s string) string
func ToTitleSpecial(c unicode.SpecialCase, s string) string
func ToUpper(s string) string
func ToUpperSpecial(c unicode.SpecialCase, s string) string
func Trim(s string, cutset string) string
func TrimFunc(s string, f func(rune) bool) string
func TrimLeft(s string, cutset string) string
func TrimLeftFunc(s string, f func(rune) bool) string
func TrimPrefix(s, prefix string) string
func TrimRight(s string, cutset string) string
func TrimRightFunc(s string, f func(rune) bool) string
func TrimSpace(s string) string
func TrimSuffix(s, suffix string) string
type Builder struct{ ... }
type Reader struct{ ... }
func NewReader(s string) *Reader
type Replacer struct{ ... }
func NewReplacer(oldnew ...string) *Replacer
BUG: The rule Title uses for word boundaries does not handle Unicode punctuation properly.
We can now 'dig down' to obtain the documentation for the TrimSpace function wthin the strings package:
$ go doc strings.TrimSpace
func TrimSpace(s string) string
TrimSpace returns a slice of the string s, with all leading and trailing
white space removed, as defined by Unicode.
and to list the methods of the strings.Replacer struct:
$ go doc strings.Replacer
type Replacer struct {
// Has unexported fields.
}
Replacer replaces a list of strings with replacements. It is safe for
concurrent use by multiple goroutines.
func NewReplacer(oldnew ...string) *Replacer
func (r *Replacer) Replace(s string) string
func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error)
Finally, we obtain the documentation for the strings.Replacer.WriteString method:
$ go doc strings.Replacer.WriteString
func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error)
WriteString writes s to w with all replacements performed.
The 'go doc' tool also has some flags including a flag to list both exported and unexported symbols (-u) and to respect case when matching symbols (-c); normally lower- case letters match either case.
Jsish
prompt$ jsish
Jsish interactive: see 'help [cmd]'
# help
Jsish interactive executes commands, uses tab for completions, and has help for the following builtin commands:
Array Boolean CData CEnum CStruct CType Channel Debugger Event File
Function Info Interp JSON Math Number Object RegExp Signal Socket
Sqlite String System Util Vfs WebSocket Zvfs assert clearInterval
console decodeURI encodeURI exec exit format isFinite isMain isNaN
load log noOp parseFloat parseInt parseOpts printf provide puts quote
require runModule setInterval setTimeout sleep source strftime strptime
unload update
Help can also take options. For example to display in a web browser try:
help -web true WebSocket
Module help can also be displayed (non-web), as in 'help Jsi_Websrv`.
Builtin modules include:
Jsi_Archive Jsi_CData Jsi_Csspp Jsi_Debug Jsi_DebugUI Jsi_GenDeep
Jsi_Help Jsi_Htmlpp Jsi_Jspp Jsi_Markdeep Jsi_Module Jsi_Safe Jsi_SqliteUI
Jsi_UnitTest Jsi_Vfs Jsi_Websrv Jsi_Wget
# help File
File.method(...)
Commands for accessing the filesystem
Methods: atime chdir chmod copy dirname executable exists extension glob isdir isfile isrelative join link lstat mkdir mknod mtime owned pwd read readable readlink realpath remove rename rootname size stat tail tempfile truncate type writable write
[File.glob options]
Option Type Description [Flags]
----------------------------------------------------------------------------
dir STRING The start directory: this path will not be prepended to results.
maxDepth INT Maximum directory depth to recurse into.
maxDiscard INT Maximum number of items to discard before giving up.
dirFilter FUNC Filter function for directories, returning false to discard. @function(dir:string)
filter FUNC Filter function to call with each file, returning false to discard. @function(file:string)
limit INT The maximum number of results to return/count.
noTypes STRKEY Filter files to exclude these "types".
prefix STRKEY String prefix to add to each file in list.
recurse BOOL Recurse into sub-directories.
retCount BOOL Return only the count of matches.
tails BOOL Returned only tail of path.
types STRKEY Filter files to include type: one or more of chars 'fdlpsbc' for file, directory, link, etc.
Perl
- When invoked as
perl -hat the command line:
Usage: perl [switches] [--] [programfile] [arguments]
-0[octal] specify record separator (\0, if no argument)
-a autosplit mode with -n or -p (splits $_ into @F)
-C[number/list] enables the listed Unicode features
-c check syntax only (runs BEGIN and CHECK blocks)
-d[:debugger] run program under debugger
-D[number/list] set debugging flags (argument is a bit mask or alphabets)
-e program one line of program (several -e's allowed, omit programfile)
-E program like -e, but enables all optional features
-f don't do $sitelib/sitecustomize.pl at startup
-F/pattern/ split() pattern for -a switch (//'s are optional)
-i[extension] edit <> files in place (makes backup if extension supplied)
-Idirectory specify @INC/#include directory (several -I's allowed)
-l[octal] enable line ending processing, specifies line terminator
-[mM][-]module execute "use/no module..." before executing program
-n assume "while (<>) { ... }" loop around program
-p assume loop like -n but print line also, like sed
-s enable rudimentary parsing for switches after programfile
-S look for programfile using PATH environment variable
-t enable tainting warnings
-T enable tainting checks
-u dump core after parsing program
-U allow unsafe operations
-v print version, patchlevel and license
-V[:variable] print configuration summary (or a single Config.pm variable)
-w enable many useful warnings
-W enable all warnings
-x[directory] ignore text before #!perl line (optionally cd to directory)
-X disable all warnings
Run 'perldoc perl' for more help with Perl.
- Running
perldoc perl, output includes (but is not limited to):
GETTING HELP
The perldoc program gives you access to all the documentation that comes
with Perl. You can get more documentation, tutorials and community
support online at <http://www.perl.org/>.
If you're new to Perl, you should start by running "perldoc perlintro",
which is a general intro for beginners and provides some background to
help you navigate the rest of Perl's extensive documentation. Run
"perldoc perldoc" to learn more things you can do with perldoc.
For ease of access, the Perl manual has been split up into several
sections.
Overview
perl Perl overview (this section)
perlintro Perl introduction for beginners
perlrun Perl execution and options
perltoc Perl documentation table of contents
Tutorials
perlreftut Perl references short introduction
perldsc Perl data structures intro
perllol Perl data structures: arrays of arrays
perlrequick Perl regular expressions quick start
perlretut Perl regular expressions tutorial
perlootut Perl OO tutorial for beginners
perlperf Perl Performance and Optimization Techniques
perlstyle Perl style guide
perlcheat Perl cheat sheet
perltrap Perl traps for the unwary
perldebtut Perl debugging tutorial
perlfaq Perl frequently asked questions
perlfaq1 General Questions About Perl
perlfaq2 Obtaining and Learning about Perl
perlfaq3 Programming Tools
perlfaq4 Data Manipulation
perlfaq5 Files and Formats
perlfaq6 Regexes
perlfaq7 Perl Language Issues
perlfaq8 System Interaction
perlfaq9 Networking
Reference Manual
perlsyn Perl syntax
perldata Perl data structures
perlop Perl operators and precedence
perlsub Perl subroutines
perlfunc Perl built-in functions
perlpod Perl plain old documentation
perldiag Perl diagnostic messages
perldeprecation Perl deprecations
perllexwarn Perl warnings and their control
perldebug Perl debugging
perlvar Perl predefined variables
perlre Perl regular expressions, the rest of the story
perlref Perl references, the rest of the story
perlobj Perl objects
perltie Perl objects hidden behind simple variables
perlipc Perl interprocess communication
perlfork Perl fork() information
perlnumber Perl number semantics
perlthrtut Perl threads tutorial
perlport Perl portability guide
perllocale Perl locale support
perlunicode Perl Unicode support
perlunifaq Perl Unicode FAQ
perlunitut Perl Unicode tutorial
perlsec Perl security
perlmod Perl modules: how they work
perlmodlib Perl modules: how to write and use
perlmodinstall Perl modules: how to install from CPAN
perlutil utilities packaged with the Perl distribution
perlglossary Perl Glossary
perlbook Perl book information
perlcommunity Perl community information
perldoc Look up Perl documentation in Pod format
perldelta Perl changes since previous version
Perl 6
Perl 6 help is generally in a specialized text format known as POD (Plain Old Documentation). It is sometimes referred to as POD6 to distinguish it from Perl 5 POD which is slightly different and not completely compatible. Perl 6 has a local command line help app: p6doc. It also has online browsable HTML documentation at docs.perl6.org. If you want to download the HTML docs for a local copy, or just prefer to browse the documentation as a single page docs.perl6.org/perl6.html may be more to your preference. If you prefer a different format, there are utilities available to convert the POD docs to several different formats; Markdown, PDF, Latex, plain text, etc.
Individual Perl 6 scripts are to some extent self-documenting. If the script has a MAIN sub, and it is called with improper parameters, it will display an automatically generated help message showing the various possible parameters, which are required, which are optional, and what type each takes:
<lang perl6>sub MAIN(
Str $run, #= Task or file name Str :$lang = 'perl6', #= Language, default perl6 Int :$skip = 0, #= Skip # to jump partially into a list Bool :f(:$force), #= Override any skip parameter
) {
# do whatever
}</lang>
- When saved locally as main.p6 and invoked with no (or wrong) passed parameters:
Usage:
main.p6 [--lang=<Str>] [--skip=<Int>] [-f|--force] <run>
<run> Task or file name
--lang=<Str> Language, default perl6
--skip=<Int> Skip # to jump partially into a list
-f|--force Override any skip parameter
REXX
Some REXXes offer interactive help (via HELP or some other command).
Other REXXes have an HTML document or a PDF for showing command syntax and other general information on use of the language.
Each REXX has it's own documentation, and viewing it would depend on the host environment.