Odd Analogy

Jamie Jackson myspamb8 at gmail.com
Fri Jan 20 12:08:57 CST 2006


Thanks for the book. I have one small criticism, though:

A paragraph from the section on locking:

Many version control systems use a *lock-modify-unlock* model to address
> this problem. In such a system, the repository allows only one person to
> change a file at a time. First Harry must "lock" the file before he can
> begin making changes to it. Locking a file is a lot like borrowing a book
> from the library; if Harry has locked a file, then Sally cannot make any
> changes to it. If she tries to lock the file, the repository will deny the
> request. All she can do is read the file, and wait for Harry to finish his
> changes and release his lock. After Harry unlocks the file, his turn is
> over, and now Sally can take her turn by locking and editing. Figure 2.3,
> "The lock-modify-unlock solution"<http://svnbook.red-bean.com/nightly/en/svn.basic.vsn-models.html#svn.basic.vsn-models.lock-unlock.dia-1>demonstrates this simple solution.
>

I think the analogy of locking to a borrowing from a brick-and-mortar
library is either ill-conceived or poorly explained.

Locking a file is a lot like borrowing a book from the library; if Harry has
> locked a file, then Sally cannot make any changes to it.


Making edits to borrowed books is highly discouraged. ;-) But besides that,
I am having trouble making any useful connection between libraries and a
repository that would help explain locking.

IMO, if the "library" part were dropped, I think it would be a better
paragraph.

Thanks,
Jamie
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