diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 101 |
1 files changed, 78 insertions, 23 deletions
@@ -55314,11 +55314,17 @@ can immediately use to expand the given form that is being traversed. .desc The .code load -function causes a file of \*(TL code to be read and evaluated. +function causes a file containing \*(TL or \*(TX code to be read and processed. The .meta target argument is a string. +Firstly, the value in +.meta target +is converted to an +.I "effective pathname" +as follows. + If .meta target specifies a pure relative pathname, as defined by the @@ -55339,42 +55345,91 @@ then a pure relative pathname is used as-is, and thus resolved relative to the current working directory. -If -.meta target -has no suffix, then +Once the effective path name is determined, .code load -first tries to load the un-suffixed name. If that cannot be opened, the -.str .tl -suffix is added to the path and another attempt is made. If that fails, -an exception is thrown. - -If +first tries to open that exact path name. +If this succeeds, then the file will be treated as containing \*(TL, +unless .meta target -has a -.str .txr -suffix, it is assumed to be a \*(TX pattern language file, and -an exception of type -.code eval-error -is thrown, since this is not supported. +ends ends with the +.code .txr +suffix, in which case the file will be treated as containing +\*(TX pattern language syntax. -If -.meta target -is successfully resolved and opened, \*(TL forms are read from the file -in succession. Each form is evaluated as if by the +If loading the original effective path name fails, and that name is unsuffixed, +then the +.code .tl +suffix is added and another attempt is made. If that succeeds, +the file will be treated as \*(TL. + +If a file is successfully resolved and opened for \*(TL processing, +then \*(TL forms are read from it in succession. Each form is evaluated as if +by the .code eval function, before the next form is read. If a syntax error is encountered, an exception of type .code eval-error is thrown. -Over the evaluation of the forms, the special variable -.code *load-path* -to the path name of that file. +If a file is successfully resolved and opened for \*(TX processing, +then its contents are parsed in their entirety as a \*(TX +query. If the parse is successful, the query is executed. +Previous \*(TX pattern variable and function bindings are in +effect. If the query binds new variables and functions, +these emerge from the +.code load +and take effect. If the parse is unsuccessful, an exception of type +.code query-error +is thrown. Parser error messages are directed to the .code *stderr* stream. +Over the evaluation of either a \*(TL or \*(TX file, +.code load +establishes a new dynamic binding for several special +variables. The variable +.code *load-path* +is given a new binding containing the effective path name. This excludes any +.code .tl +suffix that was added by +.codn load . +The +.code *package* +variable is also given a new dynamic binding, whose value is the +same as the existing binding. Thus if the processing of the +loaded file has the effect of altering the value of +.codn *package* , +that effect will be undone when the binding is removed +after the load completes. + +When the +.code load +function terminates normally after processing a file, +it returns +.codn nil . +If the file contains a \*(TX pattern query which is +processed to completion, the matching success or failure +of that query has no bearing on the return value of +.codn load . +Note that this behavior is different from the +.code @(load) +directive which itself fails if the loaded query +fails, causing subsequent directives not to be processed. + +A \*(TX pattern language file loaded with the Lisp +.code load +function does not have the usual implicit access to the +command line arguments, unlike a top-level \*(TX query. +If the directives in the file try to match input, they +work against the +.code *stdin* +stream. The +.code @(next) +directive behaves as it does when no more arguments +are available. + .coNP Special variable @ *load-path* .desc The |