diff options
| -rw-r--r-- | doc/guix.texi | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 665bdb028d..2082fd765c 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -2942,12 +2942,12 @@ and these dependencies are automatically added as inputs to the build processes that use them. @end itemize -Actually this mechanism is not limited to package and derivation -objects; @dfn{compilers} able to ``lower'' other high-level objects to +This mechanism is not limited to package and derivation +objects: @dfn{compilers} able to ``lower'' other high-level objects to derivations can be defined, such that these objects can also be inserted -into gexps. Another useful type of high-level object that can be -inserted in a gexp is @dfn{local files}, which allows files from the -local file system to be added to the store and referred to by +into gexps. For example, a useful type of high-level object that can be +inserted in a gexp is ``file-like objects'', which make it easy to +add files to the store and refer to them in derivations and such (see @code{local-file} and @code{plain-file} below.) @@ -3113,6 +3113,24 @@ refer to. Any reference to another store item will lead to a build error. The other arguments are as for @code{derivation} (@pxref{Derivations}). @end deffn +@cindex file-like objects +The @code{local-file} and @code{plain-file} procedures below return +@dfn{file-like objects}. That is, when unquoted in a G-expression, +these objects lead to a file in the store. Consider this G-expression: + +@example +#~(system* (string-append #$glibc "/sbin/nscd") "-f" + #$(local-file "/tmp/my-nscd.conf")) +@end example + +The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it +to the store. Once expanded, for instance @i{via} +@code{gexp->derivation}, the G-expression refers to that copy under +@file{/gnu/store}; thus, modifying or removing the file in @file{/tmp} +does not have any effect on what the G-expression does. +@code{plain-file} can be used similarly; it differs in that the file +content is directly passed as a string. + @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @ [#:recursive? #t] Return an object representing local file @var{file} to add to the store; this |