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From "Daniel F. Savarese" <>
Subject Re: next possible commons project - [regexp]
Date Thu, 26 Sep 2002 18:35:45 GMT

Steve Downey wrote:
>The odds of having two projects that require regexp packages that can also 
>tolerate having the definition of regular expression changed underneath them 
>approaches zero.

I agree with this as far as most applications are concerned.  I don't 
know the original motivation for this thread, but I can offer the reasons
why it's thought to be useful in jakarta-oro.  Having a generic API for
regular expressions allows you to write text processing classes,
for example tokenizers, whose use depends on user-defined regular
expressions.  The developer using the library can then choose a
regular expression grammar that meets his particular needs or fancy.
I view it more as a library-building convenience.  But there are some
instances where an application would make direct use of the facility.
For example, a text search tool that lets you choose a regular expression
grammar that you are familiar with.  You write one search algorithm using
a single set of interfaces, but the instances of those interfaces are
user-determined and decided at run time.  For the most part, however,
applications that depend on statically predefined regular expression
have no use for such a facility.  In addition, the facility as conceived
in jakarta-oro is not quite analogous to commons-logging because multiple
regular expression engines can coexist in the same application and are
not automatically chosen for you, while it's my understanding that
commons-logging dynamically chooses one underlying logging library (which
makes sense for logging).  In any case, if anyone who has an immediate
need for dynamically pluggable regular expression engines is welcome
to make the addition to jakarta-oro instead of waiting for us to get
around to it.


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