## punkshell - an alternative Tcl Shell
BSD license
2023-08 Note: this is **alpha** level software and still highly experimental.
### Features
- default ansi color output - toggle with 'colour on' and 'colour off' (or set NO_COLOR environment variable)
- rendering of old-school Ansi art (cp437) in the terminal
- Relatively easy compositing of text blocks containing Ansi colour codes - (or rendered versions of ansi containing movement and other controls)
```
proc welcome_test {} {
package require textblock
package require punk::ansi
package require overtype
set ansi [textblock::join -- " " [punk::ansi::ansicat src/testansi/publicdomain/roysac/roy-welc.ans 80x8]]
# Ansi art courtesy of Carsten Cumbrowski aka Roy/SAC - roysac.com
set table [[textblock::spantest] print]
set punks [a+ web-lawngreen][>punk . lhs][a]\n\n[a+ rgb#FFFF00][>punk . rhs][a]
set ipunks [overtype::renderspace -width [textblock::width $punks] [punk::ansi::enable_inverse]$punks]
set testblock [textblock::testblock 15 rainbow]
set contents $ansi\n[textblock::join -- " " $table " " $punks " " $testblock " " $ipunks " " $punks]
set framed [textblock::frame -type arc -title [a+ cyan]Compositing[a] -subtitle [a+ red]ANSI[a] -ansiborder [a+ web-orange] $contents]
}
```
- experimental functional/pattern-matching language features. (will not be performant until more work is done on script compilation)
e.g.1 basic pipeline with 2 segments
`var_pipe_output.= var_list.= list a b c |> string toupper`
e.g.2 basic pattern-match multi-assignment to variables x y & z
`x@0,y@1,z@2.= list a b c` equivalently: `x@,y@,z@.= list a b c` or even `x@,y@,z@= {a b c}`
`x/0,y/1,z/2,zz/3.= list a b c` is similar - but the use of forward-slash instead of @ will not produce a mismatch if an index is out of range.
where .= indicates following arguments form a command, and a plain = accepts only a single argument as a value
The diminutive case of this is `x= "something"` as equivalent to `set x "something"`
Assignment operations and pattern-matches are slightly optimised to bytecompile, but are unlikely to compete with raw Tcl commands performance-wise.
e.g.3 destructuring pattern-match. Get value of key 'k1' from last item in a list of dicts.
`x@end/@@k1.= list {k1 aaa} {k1 bb}` returns bbb
There are many more pattern-matching features yet to be documented.
- easy execution of externals commands with return of stdout, stderr and the exitcode of the process
The run... commands use a very basic repl-telemetry system to output more information to the console than just the return value,
but in a way which makes the return value clear. The telemetry only outputs if the command is the first word on the commandline.
- `run <comand> ...`
(return exitcode of process - and allows process writes to stderr/stdout to appear in console as they occur)
- `runout [-n] <command> ...`
(return stdout of process - no output until completion)
- `runerr [-n] <command> ...`
(return stderr of process - no output until completion)
- `runx [-n] <command> ...`
(return a dict of stdout stderr exitcode - no output until completion)
The run... commands attempt to make it clear if a called process outputs a trailing newline by displaying a trailing blank line.
The optional `-n` argument can be used to suppress a trailing newline.
`runout -n pwd` is thus **similar** to Tcl's `exec pwd`
For simple cases `exec <command>` is fine - but the equivalent `runout -n <command>` when used in the shell will display exitcode and stderr separately (whilst returning only stdout)
exec will return stdout and stderr together.
If you are on a unix-like platform, or a windows platform which has something like msys2 to provide commands like 'which' and 'grep' in the path:
Try `runx -n which grep nonexistant` vs `exec which grep nonexistant` to see the difference in terms of easy access to what was written to stderr vs stdout.
The run... commands are intended as a supplement for rather than a replacement for Tcl's exec/open.
- namespace browser (contextual - allowing running of commands within the active namespace - analogous to 'cd' for directories)
- `n/` - display child namespaces of current namespace (alias `:/`)
also `n/ <globpattern>` to restrict output
- `n/ <childns>` - if the argument doesn't contain glob chars '*' or '?' - attempt to switch to a child namespace of that name. Analogous to `cd <dir>`
list any sub namespaces of the namespace we just switched to.
- `n//` - display child namespaces and commands (alias `://`)
with colourised indication of type such as proc,alias,ensemble,oo object,oo class,imported,exported where possible.
(renamed aliases and builtins and commands loaded from binaries will appear unmarked)
- `nn/` - move up one namespace towards root namespace '::' analogous to `cd ..` (alias `::/`)
- `n/new <somename>` - create a child namespace called 'somename' and switch to it in one operation. (alias `:/new`)
- cross-platform alternative to cd & ls/dir without invoking child processes. Display colourised listing of dirs and folders - with vfs indication.
- `d/` - list current directory (alias `./`)
also `d/ <globpattern>` to restrict output
- `d/ <subdir>` - switch to subdir and list contents in one operation
- `dd/` - move up one directory and output listing. Roughly equivalent to `cd ..` followed by dir or ls (alias `../`)
- `d/new <folder>` - create a child directory and switch to it in one operation. (alias `./new <folder>`)
#### missing
- raw mode REPL (read-eval-print-loop) to allow commandline completion etc. Initial version is linemode. (intention is to allow different REPLs to be plugged)
- documentation!
- tests
- signal handling on unix-like platforms (ctrl-c implemented on windows only)
#### very unripe parts:
- commandline options - in need of urgent work to document and lock down specifics - in particular: punkshell somescript.tcl needs a fix to emit errors.
- shellfilter - api is clumsy
- scriptlib - will likely be reorganised/pruned significantly