[Omake] How to pass an empty string to concat()?

[Dmitry Bely]

On Dec 1, 2007 11:03 PM, Jason Hickey <jyh at cs.caltech.edu> wrote:

Jason,

Thanks for the explanation. It seems to be quite clear except

> When you wrote d=$''... the string literal was never terminated.

Why? What is the difference between $'' and $' ' (two single quotes in
both cases)? And how to leave osh if I happen to write an unterminated
string?

> For what you are trying to do, we have contemplated a sed-like string-
> substitution function, but have yet to implement it.
>
> foreach doesn't iterate over strings.  Here is one way it could be
> written using a while-loop.
>
> # "Forward-slash" name
> fsname(s) =
>      s = $"$s"    # Make sure the argument is a string
>      len = $(s.length)
>      i = 0
>      text[] =
>      while $(lt $i, $(len))
>         c = $(s.nth $i)
>         if $(equal $c, \\)
>             c = /
>             export
>         text[] += $c
>         i = $(add $i, 1)
>      concat($(EMPTY), $(text))
>
> println($(fsname c:\a\b\c))
> # Prints c:/a/b/c

I found the similar way even without concat():

fslash(s) =
  s = $(string $(s))
  len = $(s.length)
  i = $(int 0)
  res =
  while $(lt $(i), $(len))
    c = $(s.nth $i)
    if $(equal $(c), \\)
      c = /
      export
    res = $(res)$(c)
    i = $(add $(i), 1)
  return $(res)

- Dmitry Bely