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Diffstat (limited to 'libslang/doc/tm/rtl/eval.tm')
| -rw-r--r-- | libslang/doc/tm/rtl/eval.tm | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/libslang/doc/tm/rtl/eval.tm b/libslang/doc/tm/rtl/eval.tm new file mode 100644 index 0000000..3c1e66c --- /dev/null +++ b/libslang/doc/tm/rtl/eval.tm @@ -0,0 +1,119 @@ +\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 + |