Re: file function purpose
Thanks for taking the time to explain. I understand, now. On Wed, Oct 17, 2018, 4:43 PM wrote: > Typo, in my example (car (file)) of course returns "somepath/" (contains > the directory separator '/'). > > You can easily test the behaviour by creating a file foo.l containing > the following single line: > (out NIL (prinl (car (file > > Then start pil repl and load this file once directly without a path and > once with its absolute path: > : (load "foo.l") > / > -> "./" > : (load "/home/user/foo.l") > /home/user/ > -> "/home/user/" > > Notice here the output is first the print and then -> prefixes the > return value of the loaded script, which of course is the same string we > just printed. > > Am 2018-10-17 22:27, schrieb andr...@itship.ch: > > So during execution of (load "somepath/somefile.l") the code (car > > (file)) returns "somepath". > > For this the (car (file)) has to be placed within somefile.l on top > > level (code that gets executed directly during the load, not e.g. as > > part of a function definition unless it is called as `read macro). > > -- > UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe >
Re: file function purpose
Typo, in my example (car (file)) of course returns "somepath/" (contains the directory separator '/'). You can easily test the behaviour by creating a file foo.l containing the following single line: (out NIL (prinl (car (file Then start pil repl and load this file once directly without a path and once with its absolute path: : (load "foo.l") / -> "./" : (load "/home/user/foo.l") /home/user/ -> "/home/user/" Notice here the output is first the print and then -> prefixes the return value of the loaded script, which of course is the same string we just printed. Am 2018-10-17 22:27, schrieb andr...@itship.ch: So during execution of (load "somepath/somefile.l") the code (car (file)) returns "somepath". For this the (car (file)) has to be placed within somefile.l on top level (code that gets executed directly during the load, not e.g. as part of a function definition unless it is called as `read macro). -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: file function purpose
Hi Curtis The purpose of (file) and the given examples makes only really sense in a specific context, which indeed is not further explained there. Additionally, for understanding this it's important to know that: During execution of (load), the loaded file is the current input stream. Meant is the "read" step of the picolisp interpreter (the R in REPL), when the source code is turned into the binary picolisp representation within memory (pointers and cells). So during execution of (load "somepath/somefile.l") the code (car (file)) returns "somepath". For this the (car (file)) has to be placed within somefile.l on top level (code that gets executed directly during the load, not e.g. as part of a function definition unless it is called as `read macro). This way the loaded file can get loaded using a indirect path, and the loaded file can still find out how it got loaded (via which path) and so re-use that path to load another file directly in the same directory as in (load (pack (car (file)) "localFile.l")) or the path information can be stored in a global variable as in (setq *Nanomsg (pack (car (file)) "lib/libnanomsg.so")). When only (load)ing files from the same directory (no subdirectories), it has indeed no effect. But when this is used in a file meant to be further included in other projects which do not necessarily (load) it using always the same path, this construct allows that the included file still can do further loading with paths relative to the files own location and the including project has not to care about path/directory structure for additional indirectly loaded files. The alternative would be to use (chdir "somepath/" (load "somefile.l")) in the including project so that during execution of (load "somefile.l") the current directory is guaranteed to be the local directory of "somefile.l". Best regards, beneroth Am 2018-10-17 20:59, schrieb Curtis: What I mean to say is, it looks as though, from where "file" is being called, it would always return NIL. On Wed, Oct 17, 2018 at 1:19 PM Curtis wrote: I'm a little confused by the purpose of the (file) function's use in the example given here: https://software-lab.de/doc/refF.html#file The example is: (load (pack (car (file)) "localFile.l")) # Load a file in same directory But, doesn't (load "localFile.l") do the same thing? I noticed the same combination of pack, car, file here: https://github.com/aw/picolisp-nanomsg/blob/master/EXPLAIN.md (setq *Nanomsg (pack (car (file)) "lib/libnanomsg.so")) Isn't it the same thing as just (setq *Nanomsg "lib/libnanomsg.so"))? -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
Re: file function purpose
What I mean to say is, it looks as though, from where "file" is being called, it would always return NIL. On Wed, Oct 17, 2018 at 1:19 PM Curtis wrote: > > I'm a little confused by the purpose of the (file) function's use in > the example given here: https://software-lab.de/doc/refF.html#file > The example is: (load (pack (car (file)) "localFile.l")) # Load a > file in same directory > > But, doesn't (load "localFile.l") do the same thing? > > I noticed the same combination of pack, car, file here: > https://github.com/aw/picolisp-nanomsg/blob/master/EXPLAIN.md > (setq *Nanomsg (pack (car (file)) "lib/libnanomsg.so")) > > Isn't it the same thing as just (setq *Nanomsg "lib/libnanomsg.so"))? -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
file function purpose
I'm a little confused by the purpose of the (file) function's use in the example given here: https://software-lab.de/doc/refF.html#file The example is: (load (pack (car (file)) "localFile.l")) # Load a file in same directory But, doesn't (load "localFile.l") do the same thing? I noticed the same combination of pack, car, file here: https://github.com/aw/picolisp-nanomsg/blob/master/EXPLAIN.md (setq *Nanomsg (pack (car (file)) "lib/libnanomsg.so")) Isn't it the same thing as just (setq *Nanomsg "lib/libnanomsg.so"))? -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
