2009/12/22 Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com>:
> Can someone justify why the first sentence would be needed at all:
>    file position: (0 max: position-150).
>    preamble := method getPreambleFrom: file at: (0 max: position - 3).
>
> in ChangeSet>>#scanVersionsOf:class:meta:category:selector:
> and in VersionsBrowser>>#scanVersionsOf:class:meta:category:selector:
>
> My guess is no-one given that the first thing #getPreamble:at: will do
> with the file is
>    file position: (0 max: position - 3).
>
> Just the kind of code I spend too many time on, trying to figure what
> I did not understand when there is nothing to understand but code is
> dead...
> While at it, also explain me why so much code is duplicated in Squeak ;)
>

Hehe, you forgot
MCMethodDefinition>>scanForPreviousVersion
which is almost identical to the above ones, except some minor changes.
I just stared at same method(s) couple hours ago. :)

The way how VersionBrowser detects an older versions of method is
total mystery to me.
I doubt that it scans the whole .changes and .sources files, otherwise
it wouldn't be so fast,
or i underestimated the squeak's file handling speed :)

Oh wait, i think i understood a bit.
it looks for a #methodsFor: prior:  pattern
and by reading a value of prior: argument it knows where to look
further in chain.

What i would do, if i would be cleaning up this mess, is to change ALL
sourcePointers to point at the beginning
of the method's stamp, instead of pointer to the beginning of method source.
Then, reader could easily read a method stamp/preamble
#nextChunk
and its source
#nextChunk

and no more black voodoo rewinding the stream back by a 150 ... to
figure out the preamble.

And of course, i'm itching to make source pointer to be an arbitrary
integer value - because new method trailers
support that ;)


> End of rant :)
>
> Nicolas
>


-- 
Best regards,
Igor Stasenko AKA sig.