Re: string function: definition of a function

[James R. V. Z. <jr...@co...>]

Petr Mikulik <mi...@ph...> writes:

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> > I propose the patch below, which adds a function that returns the
> > string that defines a specified user defined function.

I have committed the code that Ethan Merritt posted.  I may commit my
original implementation of definition() as well, if only because I can
touch type that faster (no upper case :-).

> I see it gives the following:
>	   GPFUN_f = "f(x,y)=x+y+20"
>	   GPFUN_g = "g(x,y)=x*y"
>
> I wonder how I can get the definition part only, i.e. "x+y+20" or "x*y".
>
> Maybe you could add another variable
>	   GPFUN__f = "x+y+20"

Not very mnemonic.

> I thought there are some "string" functions that could allow this,
> but it seems we don't have "string index" or "string split"
> functions.  Maybe it would be also useful to have
>	   strindex("hello world", "llo")  => 3
>	   strsplit("hello=world", "=", 0) => "hello"
>	   strsplit("hello=world", "=", 1) => "="
>	   strsplit("hello=world", "=", 2) => "world"

I agree.  Yours are inspired by awk, I think.  We could argue whether
indexes should start with 0 instead of 1.  I suggest the second
argument of strsplit should be like the second argument of strspn in
C: tokens are separated by one or more characters from that string,
and the separators found are returned.  E.g.
         strsplit("hello, world", " ;," , 1) => ", "
         strsplit("hello, world", " ;," , 2) => "world"
         strsplit("hello, world",   "," , 1) => ","
         strsplit("hello, world",   "," , 2) => " world"

To go along with strindex, I would also like to see:
         substr(string, index, length)

      - Jim Van Zandt