gnuplot-beta

tilde expansion failure

[<bma...@we...>]

Currently tilde expansion of paths like "~/gnuplot.history" via gp_expand_tilde() 
on Windows 9x will fail unless the user sets the HOME environment variable.
The string containing the path is left unchanged and does therefore not contain
a valid path. 

This problem came up while I was working on the GNUPLOT_HISTORY patch (see SF).
It applies to locating wgnuplot.ini as well as tilde expansion in "load/save" commands.
I could think of different solutions:

1) Issue a warning that a certain functionality (e.g. saving of history) of gnuplot 
requires HOME to be set and do nothing if it is not. (I.e. don't load/save history.)

2) Use a default directory instead, where 'default' could be the current
directory or the directory where gnuplot.exe resides. The first being more
reasonable for "load/save" commands and the later for locating the history
file and wgnuplot.ini.

3) Use a completely different approach to locate files on Windows and disable
tilde expansion there as most users of that platform don't know that 
concept anyway. (No, this would not introduce a lot of #ifdefs. Only
gp_expand_tilde would have to be modfied.

What would be a good solution?


Bastian

Re: tilde expansion failure

[Hans-Bernhard B. <br...@ph...>]

Bastian M=E4rkisch wrote:
> Currently tilde expansion of paths like "~/gnuplot.history" via gp_expa=
nd_tilde()=20
> on Windows 9x will fail unless the user sets the HOME environment varia=
ble.

And because that's bad,  wgnuplot prints this message in such case,=20
right on the startup screen:

          warning: no HOME found


> The string containing the path is left unchanged and does therefore not=
 contain
> a valid path.=20

There's not much that could usefully be done about that --- there's no=20
single replacement that would be equally applicable for all Windows=20
platforms.

Now that we have the code to locate a suitable fall-back location (for=20
wgnuplot.ini), arguably all other state save files should go there, too
(i.e. gnuplot.ini, the cross-session history file, and whatever else).

> 2) Use a default directory instead, where 'default' could be the curren=
t
> directory or the directory where gnuplot.exe resides.=20

That's pretty much guaranteed to be wrong (not to mention isn't even=20
accessible to normal users on a properly installed, modern Windows).

Re: tilde expansion failure

[Bastian M. <bma...@we...>]

Hans-Bernhard Broeker wrote:
> Bastian M=E4rkisch wrote:
>=20
>> Currently tilde expansion of paths like "~/gnuplot.history" via=20
>> gp_expand_tilde() on Windows 9x will fail unless the user sets the=20
>> HOME environment variable.
>=20
>=20
> And because that's bad,  wgnuplot prints this message in such case,=20
> right on the startup screen:
>=20
>          warning: no HOME found
>=20
>=20
>> The string containing the path is left unchanged and does therefore=20
>> not contain
>> a valid path.=20
>=20
>=20
> There's not much that could usefully be done about that --- there's no =

> single replacement that would be equally applicable for all Windows=20
> platforms.
>=20
> Now that we have the code to locate a suitable fall-back location (for =

> wgnuplot.ini), arguably all other state save files should go there, too=

> (i.e. gnuplot.ini, the cross-session history file, and whatever else).

Agreed. Possibly it would be even better to have a %APPDATA%\gnuplot
directory in that case.

>=20
>> 2) Use a default directory instead, where 'default' could be the curre=
nt
>> directory or the directory where gnuplot.exe resides.=20
>=20
>=20
> That's pretty much guaranteed to be wrong (not to mention isn't even=20
> accessible to normal users on a properly installed, modern Windows).

That's why I propsed it as as a fall-back for older versions of Windows
(like Win9x) only ...

I would propose the following behaviour:

	1) Try %HOME% directory from environment. That way
	   gnuplot can adjust to user preferences and it won't
	   break unix-like builds on Windows (cygwin)

	2) Try SHGetSpecialFolderPath() or %APPDATA%, if available.
	   Optionally use %APPDATA%\gnuplot directory instead.

	3) Issue a warning message (no HOME found) and give up. This
	   means gnuplot now requires HOME to be set for certain
	   functionality.

Is that reasonable now?


--=20
Bastian M=E4rkisch
Physikalisches Institut, Universit=E4t Heidelberg
Philosophenweg 12
69120 Heidelberg
Tel.: +49-6221-549239
Fax: +49-6221-549343

Re: tilde expansion failure

[Hans-Bernhard B. <br...@ph...>]

Bastian Maerkisch wrote:
> I would propose the following behaviour:
> 
>     1) Try %HOME% directory from environment. That way
>        gnuplot can adjust to user preferences and it won't
>        break unix-like builds on Windows (cygwin)

You're forgetting defined behaviour.  See "help environment", and what 
it says abyout %GNUPLOT%.

>     3) Issue a warning message (no HOME found) and give up. This
>        means gnuplot now requires HOME to be set for certain
>        functionality.

No.  That would be too harsh.  The wording of that warning may have to 
change, but bailing out is IMHO unacceptable, when the only problem is 
that a feature the majority of Windows users don't know about would fail 
to work.  They'll notice as they get there.