First understand the difference between
[embedding vs. extending].  If you decide
that embedding is the approach you want,
this page is meant to record advice about
best practices.

In this example we will create a
shell program that embeds Tcl and
an extension by the name ''foo''.
This type of program is sometimes
known as a [big wish].

A Tcl interpreter (literally, a ''Tcl_Interp*'')
gets extended by a Tcl extension by being
passed to one of two initialization routines provided
by the extension library.  For the ''foo'' extension,
the names of these initialization routines are
''Foo_Init'' and ''Foo_SafeInit''.  Normal, or ''trusted''
interpreters are passed to the ''Foo_Init'' routine,
while safe interpreters are passed to the ''Foo_SafeInit''
routine.

Since we have chosen embedding in this example, we
will directly call the ''Foo_Init'' routine on the
master interpreter of our [big wish] (foosh?) that
contains foo.

Here is a sketch of what the C code for
out [big wish] program should look like:

  #include <tcl.h>