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\function{autoload}
\synopsis{Load a function from a file}
\usage{autoload (String_Type funct, String_Type file)}
\description
The \var{autoload} function is used to declare \var{funct} to the
interpreter and indicate that it should be loaded from \var{file} when
it is actually used.
\example
Suppose \var{bessel_j0} is a function defined in the file
\var{bessel.sl}. Then the statement
#v+
autoload ("bessel_j0", "bessel.sl");
#v-
will cause \var{bessel.sl} to be loaded prior to the execution of
\var{bessel_j0}
\seealso{evalfile}
\done
\function{byte_compile_file}
\synopsis{Compile a file to byte-code for faster loading.}
\usage{byte_compile_file (String_Type file, Integer_Type method)}
\description
The \var{byte_compile_file} function byte-compiles \var{file}
producing a new file with the same name except a \var{'c'} is added
to the output file name. For example, \var{file} is
\exmp{"site.sl"}, then the function produces a new file named
\exmp{site.slc}.
\notes
The \var{method} parameter is not used in the current
implementation. Its use is reserved for the future. For now, set
it to \exmp{0}.
\seealso{evalfile}
\done
\function{eval}
\synopsis{Interpret a string as \slang code}
\usage{eval (String_Type expression, [,String_Type namespace])}
\description
The \var{eval} function parses a string as S-Lang code and executes the
result. If called with the optional namespace argument, then the
string will be evaluated in the specified namespace.
This is a useful function in many contexts such as dynamically
generating function definitions where there is no way to generate
them otherwise.
\example
#v+
if (0 == is_defined ("my_function"))
eval ("define my_function () { message (\"my_function\"); }");
#v-
\seealso{is_defined, autoload, evalfile}
\done
\function{evalfile}
\synopsis{Interpret a file containing \slang code.}
\usage{Integer_Type evalfile (String_Type file, [,String_Type namespace])}
\description
The \var{evalfile} function loads \var{file} into the interpreter
and executes it. If called with the optional namespace argument,
the file will be loaded into the specified namespace, which will be
created if necessary. If no errors were encountered, \exmp{1} will
be returned; otherwise, a \slang error will be generated and the
function will return zero.
\example
#v+
define load_file (file)
{
ERROR_BLOCK { _clear_error (); }
() = evalfile (file);
}
#v-
\notes
For historical reasons, the return value of this function is not
really useful.
The file is searched along an application-defined load-path. The
\ifun{get_slang_load_path} and \ifun{set_slang_load_path} functions
may be used to set and query the path.
\seealso{eval, autoload, set_slang_load_path, get_slang_load_path}
\done
\function{get_slang_load_path}
\synopsis{Get the value of the interpreter's load-path}
\usage{String_Type get_slang_load_path ()}
\description
This function retrieves the value of the delimiter-separated search
path used for loading files.
\notes
Some applications may not support the built-in load-path searching
facility provided by the underlying library.
\seealso{}
\done
\function{set_slang_load_path}
\synopsis{Set the value of the interpreter's load-path}
\usage{set_slang_load_path (String_Type path)}
\description
This function may be used to set the value of the
delimiter-separated search path used by the \ifun{evalfile} and
\ifun{autoload} functions for locating files.
\example
#v+
public define prepend_to_slang_load_path (p)
{
variable s = stat_file (p);
if (s == NULL) return;
if (0 == stat_is ("dir", s.st_mode))
return;
variable d = path_get_delimiter ();
set_slang_load_path (strcat (p, d, get_slang_load_path ()));
}
#v-
\notes
Some applications may not support the built-in load-path searching
facility provided by the underlying library.
\seealso{get_slang_load_path, path_get_delimiter, evalfile, autoload}
\done
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