OpenEuphoria

1. random filenames

• Posted by Hayden McKay <hmck1 at dodo.com.au> Mar 19, 2007
• 537 views

Doe's anyone know how to implement a small runtime cross-platform random
filename generator?

I'm currently just adding the '~' char to the filename
ie: filename = '~' & filename

I've written a small template but it will return unprintable chars;

function TempFile(sequence mode)
    sequence s

    s = repeat(-1, 8)
    for j = 1 to 8 do            -- DOS filename compatablity
        s[j] = rand(125 + 1)
    end for

    s &= ".TMP"

    return OpenFile(s, mode)

end function

Maybee a 'set_rand()' might fix?

3. Re: random filenames

• Posted by Jason Gade <jaygade at yahoo.com> Mar 19, 2007
• 511 views

CChris wrote:
> You probably can add a random touch to my unique.e in the archive.
> 
> CChris

Where is that? I couldn't find it by searching for "unique" in the archive, nor
by trying "unique.e" or "unique.zip" directly.

--
"Any programming problem can be solved by adding a level of indirection."
--anonymous
"Any performance problem can be solved by removing a level of indirection."
--M. Haertel
"Premature optimization is the root of all evil in programming."
--C.A.R. Hoare
j.

5. Re: random filenames

• Posted by Jason Gade <jaygade at yahoo.com> Mar 19, 2007
• 505 views
• Last edited Mar 20, 2007

Thanks, Christian. I'll check it out.

I've seen the solution to this in *nix shell scripts -- basically the script
grabs the PID (process ID) of it's own process and uses that (maybe with a random
or iterative number added on).

I don't know how easy it is to get the PID under Windows though. I found some
tools online to do so but I didn't see if there was anything already "built-in"
to Windows to do it (like with system()), without calling into the OS itself.

--
"Any programming problem can be solved by adding a level of indirection."
--anonymous
"Any performance problem can be solved by removing a level of indirection."
--M. Haertel
"Premature optimization is the root of all evil in programming."
--C.A.R. Hoare
j.

7. Re: random filenames

• Posted by Jason Gade <jaygade at yahoo.com> Mar 19, 2007
• 521 views
• Last edited Mar 20, 2007

jacques deschênes wrote:
> 
> Hi Hayden,
> the reason for unprintable character is that rand(125)+1 generate values
> between
> 1 and 126 and codes below 32 are unprintable
> replace rand(125)+1 by   rand(93) + 32
> but beware that some characters like '\' are forbidden in windows filenames
> so a better choice could be rand(26)+'a' (limit to lower case letters)
> But all this is not 100% collision proof.
> 
> regards,
> Jacques D.
> 
> Hayden McKay wrote:
> > 
> > Doe's anyone know how to implement a small runtime cross-platform random
> > filename
> > generator?
> > 
> > I'm currently just adding the '~' char to the filename
> > ie: filename = '~' & filename
> > 
> > I've written a small template but it will return unprintable chars;
> > 
> > }}}
<eucode>
> > function TempFile(sequence mode)
> >     sequence s
> > 
> >     s = repeat(-1, 8)
> >     for j = 1 to 8 do            -- DOS filename compatablity
> >         s[j] = rand(125 + 1)
> >     end for
> > 
> >     s &= ".TMP"
> > 
> >     return OpenFile(s, mode)
> > 
> > end function
> > </eucode>
{{{

> > 
> > Maybee a 'set_rand()' might fix?

Here's an (untested) idea:

constant CHARLIST = "abcdefghijklmnopqrstuvwxyz1234567890"
function TempFile(sequence mode)
    sequence s
    s = repeat(-1, 8)

    integer charcount
    charcount = length(CHARLIST)

    for j = 1 to 8 do -- DOS filename compatibility
        s[j] = CHARLIST[rand(charcount)]
    end for

    s &= ".TMP"

    return OpenFile(s, mode)

end function

I just noticed that Christian Cuvier's upload is showing up, I haven't looked at
it yet.

--
"Any programming problem can be solved by adding a level of indirection."
--anonymous
"Any performance problem can be solved by removing a level of indirection."
--M. Haertel
"Premature optimization is the root of all evil in programming."
--C.A.R. Hoare
j.

9. Re: random filenames

• Posted by Hayden McKay <hmck1 at dodo.com.au> Mar 20, 2007
• 661 views

Thanks to all for your input guys. I've know adapted Jason's technique but
instead of the byte array i'm useing;

if ch >= 'A' and ch <= 'Z'
or ch >= 'a' and ch <= 'z'
-- etc...

then check filename with 'dir()' and recurce if need to.

nb. the code had to remain small and efficiant, it's later going to be
translated to assembly by someone else.

11. Re: random filenames

• Posted by CChris <christian.cuvier at agriculture.gouv.fr> Mar 20, 2007
• 519 views

Jason Gade wrote:
> 
> Hayden McKay wrote:
> > 
> > Thanks to all for your input guys. I've know adapted Jason's technique but
> > instead
> > of the byte array i'm useing;
> > }}}
<eucode>
> > if ch >= 'A' and ch <= 'Z'
> > or ch >= 'a' and ch <= 'z'
> > -- etc...
> > </eucode>
{{{

> > then check filename with 'dir()' and recurce if need to.
> > 
> > nb. the code had to remain small and efficiant, it's later going to be
> > translated
> > to assembly by someone else.
> 
> Can you share the code?
> 
> I think a look-up table (which was my technique) would be more efficient even
> in assembler than a decision table. But I'm not an experienced assembly
> programmer.
> 
> --
> "Any programming problem can be solved by adding a level of indirection."
> --anonymous
> "Any performance problem can be solved by removing a level of indirection."
> --M. Haertel
> "Premature optimization is the root of all evil in programming."
> --C.A.R. Hoare
> j.

It is. Obviously you are using more memory to pay for an increase in speed.
This is even more true on pipelined CPUs, where bad branch prediction has a
 sgnificant cost.

CChris

13. Re: random filenames

• Posted by Jason Gade <jaygade at yahoo.com> Mar 20, 2007
• 521 views

Yeah, I always forget whether to specify "size" or "speed" when using the word
"efficiency". I usually think speed to myself but sometimes the tradeoff becomes
rather obvious.

Is this for an embedded project or something?

--
"Any programming problem can be solved by adding a level of indirection."
--anonymous
"Any performance problem can be solved by removing a level of indirection."
--M. Haertel
"Premature optimization is the root of all evil in programming."
--C.A.R. Hoare
j.

15. Re: random filenames

• Posted by CChris <christian.cuvier at agriculture.gouv.fr> Mar 23, 2007
• 546 views

Jason Gade wrote:
> 
> Thanks, Christian. I'll check it out.
> 
> I've seen the solution to this in *nix shell scripts -- basically the script
> grabs the PID (process ID) of it's own process and uses that (maybe with a
> random
> or iterative number added on).
> 
> I don't know how easy it is to get the PID under Windows though. I found some
> tools online to do so but I didn't see if there was anything already
> "built-in"
> to Windows to do it (like with system()), without calling into the OS itself.
> 
> --
> "Any programming problem can be solved by adding a level of indirection."
> --anonymous
> "Any performance problem can be solved by removing a level of indirection."
> --M. Haertel
> "Premature optimization is the root of all evil in programming."
> --C.A.R. Hoare
> j.

kernel32.dll exports a GetCurrentProcessId() function that just returns that:

include dll.e
constant kernel32=open_dll("kernel32.dll"),
getPID=define_c_func(kernel32,"GetCurrentProcessId",{},C_LONG)
-- if using win32lib, kernel32 is already known, and it may be better to use
-- registerw32Function() and w32Func() iinstead of the bare Eu builtins.

function myPID() 
return c_func(getPID,{})
end function

CChris