diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 59 |
1 files changed, 51 insertions, 8 deletions
@@ -2858,8 +2858,9 @@ as a filter. See Function Filters below. The filter directive passes one or more variables through a given filter or chain or filters, updating them with the filtered values. -.coIP @(load) -The load directive loads another \*(TX file and interprets its contents. +.coSS @ @(load) and @ @(include) +These directives allow \*(TX programs to be modularized. They bring in +code from a file, in two different ways. .coIP @(do) The do directive is used to evaluate \*(TL expressions, discarding their @@ -6662,14 +6663,17 @@ call goes to the toplevel definition. .SH* MODULARIZATION -.dir load +.dirs load include The syntax of the .code load -directive is: +and +.code include +directives is: .cblk .mets @(load << expr ) +.mets @(include << expr ) .cble Where @@ -6689,13 +6693,38 @@ attempt is made. Thus load expressions need not refer to the suffix. In the future, additional suffixes may be searched (compiled versions of a file). -Loading is performed at evaluation time; it is not a source file inclusion -mechanism. A \*(TX script is read from beginning to end and parsed prior to -being evaluated. +The two directives differ as follows. The action of +.code load +is not performed immediately but at evaluation time. Evaluation time +occurs after a \*(TX program is read from beginning to end and parsed. +The action of +.code include +is performed immediately, as the code is being scanned and parsed. +That is to say, as the \*(TX parser encounters +.code @(include) +it processes it immediately. The included material is read and parsed, and its +syntax tree is substituted in place of the +.code include +directive. The parser then +continues processing the original file after the +.code include +directive. + +Note: the +.code include +directive is useful for loading \*(TX files which contain Lisp macros +which are needed by the parent program. The parent program cannot use +.code load +to bring in macros because macros are required during expansion, which +takes place prior to evaluation time, whereas +.code load +doesn't execute until evaluation time. See also: the .code *self-path* -variable in \*(TL. +and +.code stdlib +variables in \*(TL. .SH* OUTPUT @@ -25213,6 +25242,20 @@ special builds of \*(TX for small systems. .desc This variable holds the invocation path name of the \*(TX program. +.coNP Special variable @ stdlib +The +.code stdlib +variable expands to the directory where the \*(TX standard library +is installed. It can be referenced in +.code @(load) +and +.code @(include) +directives via quasiliteral substitution, as in, for example: + +.cblk + @(include `@stdlib/extract`) +.cble + .SS* Debugger \*(TX has a simple, crude, built-in debugger. The debugger is invoked by adding the |