Automatic Loading of Packages
Other tutorials have discussed explicit loading of
Mathematica packages using
<<package and
Needs[package]. Sometimes, however, you may want to set
Mathematica up so that it automatically loads a particular package when the package is needed.
You can use
DeclarePackage to give the names of symbols which are defined in a particular package. Then, when one of these symbols is actually used,
Mathematica will automatically load the package where the symbol is defined.
| DeclarePackage["context`",{"name1","name2",...}] |
| declare that a package should automatically be loaded if a symbol with any of the names  is used |
Arranging for automatic loading of packages.
| Out[1]= |  |
When you first use
Grad,
Mathematica automatically loads the package that defines it.
| Out[2]= |  |
When you set up a large collection of
Mathematica packages, it is often a good idea to create an additional "names file" which contains a sequence of
DeclarePackage commands, specifying packages to load when particular names are used. Within a particular
Mathematica session, you then need to load explicitly only the names file. When you have done this, all the other packages will automatically be loaded if and when they are needed.
DeclarePackage works by immediately creating symbols with the names you specify, but giving each of these symbols the special attribute
Stub. Whenever
Mathematica finds a symbol with the
Stub attribute, it automatically loads the package corresponding to the context of the symbol, in an attempt to find the definition of the symbol.
