Changes between Version 1 and Version 2 of VincentTrial2

Timestamp:

May 11, 2005, 3:53:38 PM (19 years ago)

Author:

garonne

Comment:

--

VincentTrial2

@@ +1 @@
+= A simple example with package dependency =
+
+
 We illustrate here a simple example of package dependency.
 We show how CMT deals with a package dependency between 
 the package A and B.
+
+First we create a directory:
+{{{
+> mkdir tmp
+> cd tmp
+}}}
 
 Let's consider a package A:
@@ -43 +52 @@
 macro A_linkopts " -L$(AROOT)/$(A_tag) -lA "
 }}}
-
+We construct here only the library of the class A.
 The macro A_linkopts will be automaticaly inserted for the link operation. 
 The library location is specified with $(AROOT)/$(A_tag).
 
+Then we create the B package:
+{{{
+> cd ../../..
+> cmt create B v1
+...
+}}}
+
+With the following content:
+{{{
+> cd B/v1/src
+> more B.h
+#include <iostream>
+
+using namespace std;
+
+class B
+{
+    public:
+        B() {}
+        ~B()  {}
+        void print ();
+};
+> more B.cxx
+include "B.h"
+
+void B::print ()
+{
+        cout<<"B"<<endl;
+}
+}}}
+and the main program which needs A and B:
+{{{
+> more main.cxx
+#include "A.h"
+#include "B.h"
+int main()
+{
+    A a;
+    B b;
+    
+    a.print ();
+    b.print ();
+
+    return 0;
+}
+}}}
+
+We express this dependency in the requirements file:
+{{{
+> cd ../cmt
+> more requirements
+package B
+
+author Vincent Garonne <garonne@lal.in2p3.fr>
+
+use A v1
+
+application main main.cxx B.cxx
+}}}
+The line "use A v1" says explicitely that package B need pacckage A version 1.
+The line "application  main main.cxx B.cxx" annouces to CMT that a program must be created and for this creation,
+we need the file main.cxx and B.cxx.
+
+Then to construct the main program with CMT, we first need to give a way to localize the package A.
+This could be done by the environment variable CMTPATH. This variable contains a list of file paths where CMT
+package can be found, very similar to the PATH unix environment variable. In our case, we have:
+{{{
+> cd ../../../../tmp
+> setenv CMTPATH  `pwd`
+> echo $CMTPATH ~garonne/tmp
+}}}
+We can see also all the package depencies by the command:
+{{{
+> cd B/v1/cmt
+> cmt show uses
+# use A v1 
+#
+# Selection :
+use CMT v1r18p20050501 (/users/dsksi/garonne)
+use A v1  (/users/dsksi/garonne/tmp)
+package A
+}}}
+
+Now we can generate our executable by CMT:
+{{{
+> cmt broadcast make
+...
+}}}
+Our executable is now create for you in the Linux-i686 directory:
+{{{
+ > ls ../Linux-i686/*.exe
+../Linux-i686/main.exe
+}}}
+To execute we need first to set the LD_LIBRARY_PATH as illustrated:
+{{{
+> ../Linux-i686/main.exe
+../Linux-i686/main.exe: error while loading shared libraries: libA.so: cannot open shared object file: No such file or directory
+> setenv LD_LIBRARY_PATH ../../../A/v1/Linux-i686/
+> ../Linux-i686/main.exe
+A
+B
+}}}
+
+If we want to compile in a static way, we should add to the B requirements the macro "B_linkopts" :
+{{{
+> more ../cmt/requirements
+package B
+
+author Vincent Garonne <garonne@lal.in2p3.fr>
+
+use A v1
+
+application main main.cxx B.cxx
+
+macro B_linkopts " -static "
+> unsetenv LD_LIBRARY_PATH
+> ../Linux-i686/main.exe
+A
+B 
+}}}
+
+By this way, the LD_LIBRARY is not mandatory anymore.
+
+Another solution could be also to use only libraries for compiling, by example:
+{{{
+> more ../cmt/requirements
+package B
+
+author Vincent Garonne <garonne@lal.in2p3.fr>
+
+use A v1
+
+application main main.cxx 
+
+library  B B.cxx
+
+macro B_linkopts " -L$(BROOT)/$(B_tag) -lB "
+}}}
+The B library should be also create.
+
+
+
+
+}}}
+
+