Re: file io within starpack's vfs

On 5 February 2010 11:26, jemptymethod <[email protected]> wrote:
> I'm surprised that I can do file io within the vfs when I wrap up a
> starpack as an .exe.  Surprised but pleased: I thought that for this
> scenario I was going to have to deploy tclkit and a .kit file.
>
> What if the data I want to write within the vfs becomes "too large".
> Can the .exe expand in size?
>
> Any clarification on the inner workings of starkits/starpacks would be
> appreciated.

Not on windows. The image file (ie: tclkit.exe) is locked by the OS
when it loads the file to execute it. If you start tclkit you can do a
few tests in the console:
% cd [info nameofexecutable]
% glob *
boot.tcl config.tcl lib tclkit.ico
% set f [open junk w]
rechan89
% puts $f [string repeat a 10240]
% close $f
% glob *
boot.tcl config.tcl junk lib tclkit.ico

At the point it looks like you saved your new file - but if you exit
and restart it will have gone. The 'rechan89' channel shown above is
an in-memory stream. If we try to commit it to the database that
provides the virtual filesystem we will get an access denied error.

On unix you can modify the running image file. However on both systems
the image may be located somewhere the user does not have write
access. For this reason it is usualy best to store data in the users
home directory or a subdirectory of that. Or on windows under
$env(APPDATA).

If you dig around on the wiki.tcl.tk site you can find out more about
metakit virtual filesystems. If you are using metakit. If it was
tclkit-gui or tclkit-cli then that is a readonly version that can
access the database but not change it. Its also possible to base
starkits on zip files and use the zip vfs to load them. But the usual
'tclkit' uses a metakit database as the vfs with zlib compressed blobs
for the files. The database is appended to the end of the executable
image for a starpack.

Pat Thoyts

-- 
You received this message because you are subscribed to the "starkit" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [email protected]
For more options, visit this group at http://groups.google.com/group/starkit?hl=en