Re: Kind of a lookfor function

[David Bateman]

Keith Goodman wrote:

> On 5/30/05, avraham <address@hidden> wrote:
>  
>
> > The ultimate in confort would be to make it an octave command,
> > using the mark_as_command option, but I don't know how to do it.
> > In fact, I don't know if this is possible at all. I would be glad
> > if someone would explain how it could be done, or why it can't.
> >    
>
> I like your hack.
>
> function lookfor(target)
> disp(system(["Olookfor " target]));
>
> I added the following to my ~/.octaverc:
>
> mark_as_command lookfor
>
> Going outside of Octave means we'll never get this function back into
> Octave (as in part of an Octave release). If we can isolate the
> functionality that Octave doesn't provide (getting the output of help)
> and write the rest in Octave code, then maybe someone would replace
> the missing part with an Octave equivalent. Then we would increase of
> chances of adding lookfor to Octave
>
> A bonus feature would be a search of the help text. Now that you've
> given us a list of the function names, that shouldn't be hard. But it
> might be slow.
>  
This not a complete implementation of lookfor. Try this with "lookfor 
inverse" and it won't give you the pinv function for example. It should 
be easy enough to implement the function as is within octave itself 
without calling outside. However, a compatiable lookfor function that 
searchs in the text of the help (or at least the first line of the help) 
within octave would be more problematic. The reason is that internal to 
octave reading the help will force the function to be loaded, so this 
will be slow, and it will fill the memory with functions that are loaded 
but not used. So to do this properly the octave help code would need to 
be modified such that a call for the help of an unloaded function would 
load, read the help and then unload the function. This then breaks a 
nice little debugging trick for oct-files, where you can run octave in 
gdb, call the help of an oct-file and then type ctrl-c to return to gdb 
and since the oct-file is now loaded set a breakpoint within it.. I'd 
not like to that functionality as it is to useful, though there is 
probably a way around this in that help might not unload the function 
but lookfor would... Ok all of this is not impossible, or even that 
difficult, but its a bit of a pain.

The fact is the example above can easiliy be found with google with a 
search "site:octave.sourceforge.net/index inverse" as the category index 
in octave-forge has the help of all of the octave and octave-forge 
functions included. So given the above problems I'm not sure its worth 
implementing lookfor.

Regards
David

--
David Bateman                                address@hidden
Motorola Labs - Paris                        +33 1 69 35 48 04 (Ph) 
Parc Les Algorithmes, Commune de St Aubin    +33 1 69 35 77 01 (Fax) 
91193 Gif-Sur-Yvette FRANCE

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