Re: [jdt-ui-dev] Pre-reqs are not exported

[Randy Hudson <hudsonr@xxxxxxxxxx>]

I said "tag", singular.  So
if I do require *one* of the same pre-reqs, I need to require the same
version, so I need to copy that one tag exactly (otherwise I might pick
up a different version).

I agree class loading is very important.
 But, If everyone follows this convention, the people at the bottom
might end up with 100+ requires statements.  I guess the PDE should
help out at managing this list. Are there any benchmarks that show startup
time comparisons each way?

In my graph, I'm going to continue "promoting"
plugins even though they aren't exported.  This makes for much easier
reading, without any real loss of meaning.  Hopefully I can post a
"Map of Eclipse" pretty soon.

-randy

"Erich Gamma" <Erich_Gamma@xxxxxxx> Sent by: jdt-ui-dev-admin@xxxxxxxxxxx 12/16/2002 06:07 PM Please respond to jdt-ui-dev

To:        jdt-ui-dev@xxxxxxxxxxx         cc:        jdt-ui-dev@xxxxxxxxxxx         Subject:        Re: [jdt-ui-dev] Pre-reqs are not exported

nice words & nice try <g>

>Do you agree that by not re-exporting plugins, you are requiring
downstream
>plugins to copy *exactly* your <requires> tag?
Not really, a downstream plugin can more precisely state its dependencies.
For example a plugin that requires org.eclipse.jdt.ui
doesn't have to require org.eclipse.jdt.debug.ui plugin.
See org.eclipse.jdt.junit as example, it doesn't
require access to the org.eclipse.compare classes and
hence org.eclipse.compare isn't listed as a pre-req plugin.
By precisely stating your dependencies the class look-up
for your plugin will be more efficient since
less plugin class loaders will have to be consulted when looking-up a
class.

--erich



                    
                     
                     
                     
                     
                     
     
                    
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I still don't see the harm in exporting.  I know all of Eclipse is
consistent, I just decided to ask JDT for the reason because you guys are
so smart :-)

Do you agree that by not re-exporting plugins, you are requiring downstream
plugins to copy *exactly* your <requires> tag?  If they don't
copy it
exactly, there is a risk of the downstream plugin picking up a different
version of the pre-req than the one JDT-UI picks up, which would cause
a
link error (2 different versions of the same class) at runtime.  So,
if I
have to copy your tag exactly .... ?

Randy


                    
                     
                     
          
   "Erich Gamma"            
                     
                     
  
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       Re: [jdt-ui-dev] 
   12/16/2002 04:03 AM            Pre-reqs
are not exported                
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The convention is that dependent plug-in classes are not reexported to
clients. This makes the plugin dependencies explicit. Jdt-ui should not
be
different from other plugins in the platform.

Notice that most uses of exports are the consequence of a plugin split
(see
org.eclipse.ui as an example). In these cases exporting was used to not
break existing clients of the splitted plug-in.

--erich




                    
Randy Hudson

                    
<hudsonr@xxxxxx.c         To:
jdt-ui-dev@xxxxxxxxxxx

                    
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Pre-reqs are not exported
                    
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12/16/2002 01:56

                    
AM

                    
Please respond to

                    
jdt-ui-dev






jdt.ui requires several plugins, but the plugins are not exported. What
is
the reasoning behind not exporting these plugins to other plugins that
pre-req jdt.ui?

Much of the public API in jdt-ui requires that these other plugins be
present *AND* that they be exactly the same version.  For example,
IClassPathEntry returns an IPath, which is from org.eclipse.core.runtime.
Why make other plugins prereq both jdt.ui and core.runtime? The only reason
I can think of is to optimize for the plugin class loader.

The reason I am asking is that I am writing a graphical view of the plugin
registry.  Each plugin is represented as a box, and lines are used
to show
the plugins required by each plugin.  Plugins are positioned vertically
(in
ranks) such that all required plugins appear above a given plugin.  Long
lines make the diagram hard to read, so I added code to reduce redundant
imports. Then I found out that there weren't any redundant imports, so
I
cheated.  Without changes, a diagram of all Eclipse plugins requires
about
300 lines.  If I cheat and "export" all requires statements,
the same
diagram only needs about 85 lines.

Randy Hudson


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