On Mon, 2011-04-04 at 17:37 +0200, Jan Keirse wrote:
> su heng <ste.suheng_at_gmail.com> schreef op 04/04/2011 16:31:17:
>
> > Hi Jan,
> >
> > Please kindly refer to my below comments.
> >
> > Regards,
> > Su Heng
> >
> > On Mon, 2011-04-04 at 16:03 +0200, Jan Keirse wrote:
> > > su heng <ste.suheng_at_gmail.com> schreef op 04/04/2011 15:41:38:
> > >
> > > > Hi,
> > > >
> > > > I read the SVN book, as there are three type conflicts: text, tree
> and
> > > > properties conflict. However, I wanna know why it is a conflict. For
> > > > example, if there is a text conflict when I do merging code, I just
> know
> > > > there is an conflict but don't know why it is a conflict.
> > > >
> > > > So could u provide me some resource or hints what are the judge
> rules
> > > > for SVN to address it is a conflict, in this case, I can avoid more
> > > > conflict when I'm coding or merging. I concert the text and tree
> > > > conflict more.
> > > >
> > >
> > > Start version is A. B and C are changes to A.
> > > Change B says line 3 is 'cool!'
> > > Change C says line 3 is 'boring!'
> > > If you want to merge change B and C there's a conflict, because one
> change
> > > says the opposite of the other.
> > [suheng] : thanks, However, your example just covers one condition. Can
> > you give me a basic conflict rule policy of SVN so I can conclude all
> > conditions?
> > As your example, can I thought whenever a low revision(C) merge to a
> > high revision(when B merge to A, A will be A+1), a text conflict will be
> > pop up whatever the line is changed?
> > In your example, the precondition is file a is revision A, then the
> > same file under change B is revision B = A + n(n>0), and same file under
> > change C is revision C = B + n(n>0), when change B is merged to A, we
> > must commit it firstly(at this time revision A will be rise to A+n > B
> > && A+n > C, then do another merge I mean change C will be merged in A+n,
> > then conflict out.
> > I think if C is a branch of from revision B+n(n>1) but not A, when we
> > merge C+n(n>1) won't involve conflict, right?
> >
> > Hmm...I think it has little confusing. you can ignore my explain, just
> > suggest me the basic conflict policy is appreciated.^_^
>
> Ok, you misunderstood, C has nothing to do with B, it does not come after
> B. As a general rule: if you changed the same line there is a conflict.
>
> I'll put it another way.
> Imagine at some point velkswagen makes a car, and stores the information
> about that car in a file, named possat.txt.
> The file could have the following contents:
>
> ---------------
> brand=vw
> model=possat
> tires=4
> engine=1900
> horsepower=110
> ---------------
>
> Now at some point VW decides there possat can be sold with another logo as
> skida octevia. So they branch the file:
> octevia
> /
> possat
>
> And the file becomes:
> ---------------
> brand=skida
> model=octevia
> tires=4
> engine=1900
> horsepower=110
> ---------------
>
>
> After a few more years they decide to sell the same car under the siat
> Brand:
>
> octevia
> /
> possat
> \
> somesiat
>
>
> ---------------
> brand=siat
> model=somesiat
> tires=4
> engine=1900
> horsepower=110
> ---------------
>
> Now a clever engineer at siat notices that a car does not have 4 tires but
> 5, in case you hit a nail along the road you get an extra one in the trunk
> to get you home. So he changes tires to 5.
> Now we have 3 files, possat, somesiat and octevia. They all share the same
> origin, the possat is long out of production so we don't care about that
> anymore, but we want the octevia fixed.
> If you merge from somesiat to octevia, with the possat as mutual ancestor,
> you're going to get a problem, not with the tires but with the brand and
> model, because somesiat changed brand and model but octevia did as well,
> who holds the truth, what brand and model should be in the octevia file?
>
>
> Kind Regards,
>
> JAN KEIRSE
> ICT-AFDELING • software quality & systems • software engineer
>
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Hi Jan,
I just try the example which you provided to me. Please refer to my
flow:
###############
step 1
submit one file possat:
--------------
brand=vw
model=possat
tires=4
engine=1900
horsepower=110
---------------
file name:possat(possat_at_r159)
################
step 2
create branch octevia(possat_at_r160) and somesiat(possat_at_r161) base on
file possat
################
step 3
change file possat under somesiat branch (possat_at_r161)
--------------------
brand=siat
model=somesiat
tires=4
engine=1900
horsepower=110
---------------------
and submit can get (possat_at_r162)
change file possat under octevia branch:
----------------
brand=skida
model=octevia
tires=4
engine=1900
horsepower=110
----------------
and submit can get (possat_at_r163)
######################
step 4
change possat under trunk(possat_at_r161)
--------------
brand=vw
model=possat
tires=5
engine=1900
horsepower=110
---------------
and submit can get (possat_at_r164)
Now, I switch to branch possat or octevia, do merge from trunk.
the line 'tires=5' will be merge automatically to my branch possat or
octevia.
Strange thing, if I switch to trunk do merge from possat or octevia,
brand line and model line will be automatically overwrite trunk's lines.
I'm using ecilpse + subeclipse. I will go to shell to verify the
correctness.
Regards,
Su Heng
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Received on 2011-04-04 19:32:47 CEST