Smalltalk - Re: UUIDs

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Re: UUIDs

Posted by Peter Uhnak on Aug 11, 2015; 6:56pm
URL: https://forum.world.st/UUIDs-tp4842189p4842196.html

The UUIDGenerator has unnecessarily heavy-handed implementation, however it does adhere to the RFC specs as far as I could tell.

Which also means that it's definitely usable across images and platforms.

If anything, the weak point would be the random number generator, not UUID. And at least on unix/linux it uses /dev/urandom so it should be pretty reliable.

So ask yourself what's the probability of your PRNGs generating same 122 bits.

This thread might also interest you http://forum.world.st/Contributing-to-VoyageMongo-improving-insertion-updating-speed-td4838806.html

Peter

On Tue, Aug 11, 2015 at 8:09 PM, Sean P. DeNigris <[hidden email]> wrote:

Searching the archives, I found an interesting comment [1]:
"I think the UUIDGenerator in the image produces UUIDs which are good
enough for MC. " - Levente Uzonyi

I am pretty well confused by UUIDs in general (they seem magical) and
Pharo's implementation. The use case I have in mind is a file library which
imports files into a single folder, but changes their names to something
guaranteed to be unique so that they don't overwrite each other. Would UUIDs
work in that case? Would the image ones be "good enough"? Are
primitive-generated UUIDs guaranteed to always be unique if, say, I move the
image to another OS and continue generating them with another VM? Thanks!

[1] http://forum.world.st/UUID-and-Cog-tp2955687p2957172.html

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Cheers,
Sean
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