That's... actually a really neat idea. I'm now imagining something like
function --lua strip_prefix(str,pref) --description "Strips the second arg as a
prefix from the first"
if string.sub(str, 1, #pref) == pref then
str = string.sub(str, #pref+1)
end
print(str)
return 0
end
Ideally global variables would be visible/assignable as well, although it would
not be terrible if that had to go through a map like _globals["status"] or a
function call like fish.global("status").
Math could then be implemented as a function that evaluates its arguments with
the 'math' package brought into the local namespace, e.g.
function --lua math(...) --description "Evaluates the arguments as a
mathematical expression"
local f = loadstring("return " .. table.concat({...}, ' ')
if not f then
print_err("wtf mate")
return 1
end
local env = {}
setmetatable(env, {__index=math})
setfenv(f, env)
print(f())
return 0
end
-Kevin
On Jun 22, 2012, at 4:05 AM, Maxim Gonchar <[email protected]> wrote:
>
>> I also like your suggestion of supporting "$(…)", especially because this is
>> currently a syntax error, so there's no compatibility risk. There's some
>> synergy between this and string manipulation. There could be a built-in
>> "str" or "munge" or whatever that manipulates its argument based on other
>> parameters, e.g. "(munge --strip '/*' --repeat $PWD)" to get the last
>> component of pwd.
> I had one common 'crazy' idea. Though I think it will not be supported by
> most of people I want at least to tell about it.
> Some required capabilities (like string manipulation, math and others) can be
> implemented by embedding some scripting language in fish. It may sound a bit
> strange to use one scripting language to support another one, but there are
> advantages of such an approach. While keeping fish syntax for interactive
> usage and basic scripting, the other scripting syntax will be efficient to
> solve tasks where fish syntax is not so useful.
>
> Writing this I keep in mind an example of 'lua' language. Which is created as
> tiny and fast embeddable language.
> Lua is not the only option, but since I know only it as candidate, I will
> write about advantages of using lua.
> 1) Lua (www.lua.org) is embeddable language with small memory footprint,
> clean and consistent syntax.
> It is executed by a virtual machine, which performance is comparable to
> python
> (http://shootout.alioth.debian.org/u32/benchmark.php?test=all&lang=lua&lang2=python3).
> O by a very fast JIT compiler (http://luajit.org/performance_x86.html).
> 2) Out of the box it supports lua regular expressions. It's like a limited
> version of common regular expressions, but made with efficiency in mind.
> String manipulation, string matching.
> 3) The Perl regular expressions can be also included as a module.
> 4) Math functions with ability to add own functions.
> 5) Embedding lua (or some other scripting language) allows to introduce
> extendedable functions for string manipulation, math, condition testing.
> It allows to add new 'builtins' without hardcoding them and recompiling fish.
> The scripting will be also useful for writing completions or functions for
> keybinding without calling external programs.
>
> That's it.
> I'm not sure it's actually should be added to fish, but I see that there are
> a lot of benefits on this way.
>
> regards,
> Maxim
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