World: r3wp

or if you want to avoid loading the image twice:

i: read/binary %image.png
checksum i
i: load i

Since I might be grabbing the image as jpg and then saving it to 
png, I guess I should save it to memory as binary and do the calculation 
that way.

I use these quite often:

ifs: func [c b][either c [do b][""]] ;like if but return empty string

ifb: func [c b][either c [do b][[]]] ;like if but return empty block

my bad, thanks Dock, I can refactor to
ifs: func [c b][either c b [""]] ;like if but return empty string
ifb: func [c b][either c b [[]]] ;like if but return empty block
so ifs is like your if* 8)

Which version of rebol allows for evaluation in paths?  (i.e. block/(1+i): 
"hello" )  Or am I not remembering this correctly?

Nevermind, I think I just had a typo in my code. :)

What is the limitation on file size that REBOL 7.6 can handle?

I'm assuming there must be a iimit that open/direct can't just mount 
any file size.  I'm assuming that the limitation is roughly 2 Gigs.

I'm also assuming since a port/size is integer! that the file size 
can be no greater than 2099999999 bytes.

Since integers greater than that number cause errors.

Ok, I checked for a file size limitation in REBOL but haven't found 
one.  I noticed the documentation for open/direct for example says 
that /direct can be used for files of any size.  I don't see how 
that can be if it is calculating the size as an integer and integer 
has a limitations.

Largest 32-bit signed int is 2 ** 31 - 1 = 2'147'483'647

If REBOL internally use 32-bit unsigned, it's 2 ** 32 - 1 = 4'294'967'295

If REBOL internally use 64-bit unsigned, it's 2 ** 64 - 1 ca. = 
1.845E+19

I'm actually running an experiment now.  I'm going to write a file 
that will attempt to exceed those sizes.

:-) Be sure, you have enough HD space!

The file system might have max-size for files. I remember something 
about 2 or 4GB for some file systems.

FAT32 is the one with that limit.

Yep, hit it today on FAT32 - 4GB file was produced.

I'm on NTFS.  I'll post what I find out.

currently still writing a file which is only at 668 Megs at the moment.

Anton, you created a 4GB file using REBOL or was reading one when 
you got the error?

Sorry, not using Rebol, but in Linux, creating a file in a FAT32 
partition.

ahhh ok.

I was curious because I'm interested in what happens when I hit 2099999999 
size.

Actually a bit larger than that.

I don't know where you got that number from; If I remember correctly 
the first time you can get a problem with rebol file size is at 2 
^ 31 - 1

Oh it was a generic range number based on a algorithm I was running. 
 I expect the number to be the 32 bit signed number that John posted.

Maybe it was 2 ^ 31 - your buffer size ?

That number I posted is the highest in my algorithm I could hit.

Ok, that makes sense.

p: open/direct/write/new %/k/test.bin

b: make binary! 1000000 insert/dup b #{00} 1000000 i: 0 while [not 
error? try [insert tail p b]][i: i + 1]

created file ower 5GB here... than I stoped it.

what OS?

WIN/ ntfs

ok cool.

I want to be able to do some probes on the file once I get it to 
size.

on the port rather.

The problem is with reading anyway

You having problem reading that file now?

But not impossible I guess. Using such a big files is not practical 
imho.

I think it's when you want to seek to a position greater than 2 ^ 
31 - 1

you run into a problem then.

I'm not going to read such a file if I have only 1GB memory:)

Well I'm testing a new indexing system for TRETBASE and need to know 
some significant data to fine tune it.

That is where my interest lies Anton.

Interesting the limit for file size in REBOL is 2 ** 31

when the port/state/tail value reaches 2 ** 31 it converts it to 
a negative number and gives an error which is an "access error writing 
to port".

Now the port can still be read via open/direct but no longer accessible 
via open/seek at that point.

Not sure how OLDES was able to get his file over 5GB on NTFS as my 
test was also on NTFS.

I wonder if WRITE/APPEND allows files over 4 GB?

I would have thought that write would be using open also.