Re: executable jars and libraries
Lew wrote:
You say that as if the "java" command doesn't honor the CLASSPATH
envar, or for that matter the "-cp" option. It does, and yes, for
JARs, too.
Jan Helgesen wrote:
Could you explain, because from this post and in your answer to Mark
Space, you seem to contradict your self.
In your answer to Mark Space (Tue, 28 Apr 2009 00:02:58 -0400) you say
that -jar overrides -cp and CLASSPATH, in this post you say that it
still honours -cp and CLASSPATH when using the -jar argument.
That is not what I said, not at all, not even close. I said that the "java"
command honors "-cp" and CLASSPATH. I did not say that it does so with the
"-jar" option; quite the opposite.
A couple of points:
1. how does the Class-Path declaration resolve to paths on different
platforms?
It translates the slashes into the local path separator character, I suppose.
The only safe way to use "Class-Path" is with relative paths.
2. how does jaca deal with different platforms using different location
for library files when using Class-Path
What do you mean here by "library files"?
Regardless, it uses the "Class-Path" manifest entry to locate the library
files, just as described in the docs for "jar", such as the tutorial, the link
for which I repeat here from my earlier post just upthread a few messages:
<http://java.sun.com/docs/books/tutorial/deployment/jar/downman.html>
The whole point of "Class-Path" is to eliminate problems that different
platforms' locations for dependencies would cause. By using it as the sole
source for path information, the different locations for library files are
utterly irrelevant.
It seems to me that Sun has at least broken the library semantics of
unix [sic] systems.
It has done no such thing. Apples and oranges.
http://tldp.org/HOWTO/Program-Library-HOWTO/shared-libraries.html
see section 3.2 and 3.3.1
That has nothing to do with Java.
....
In java [sic], with ther entirely own semantics, it seems to be
Precisely. Java is not UNIX, nor Windows, but in its own VM world.
The programmer dont care, or even know, where the local system has its
libraries. That would primarily have to be left to the user or the
sysadm. Sun should have followed the platform semantics,
Says who?
thats what administrators and users expect.
Not if they read the docs they don't.
So on unix [sic] that it would followed unix [sic] semantics for library searching
and added an option that enables or disables honouring of the manifest
Class-Path declaration. In the case of entirely independent jar,
java [sic] should also have the option to package everything inside a jar,
but still with the override argument to enable/disable, as mentioned above.
Java follows the semantics of searching via "-cp" and CLASSPATH, but with the
option to override those by using the "-jar" option. It already does just
what you suggest here.
--
Lew