Re: Replacing characters in a pattern rule

[John Graham-Cumming]

natch wrote:
> I have a list of directories (discovered automatically, but explicitly 
> defined for this example):
>
> DIRECTORIES := a b c
>
> Some of these directories have index.html files in them.  I wish to copy 
> these into the local directory as
>
> DIRECTORY_index.html
>
> The straight forward solution is
>
> INDEX_HTML_FILES := $(DIRECTORIES:%=%_index.html)
>
> $(INDEX_HTML_FILES): %_index.html : %/index.html
>    cp $< $@
>
> Now, this words great for immediate subdirectories.  However, I want 
> this to work recursively, for example:
>
> DIRECTORIES := a b c group/d group/e
>
> I need both directory names in the file name, such as:
>
> group_d_index.html    group_e_index.html
>
> I can easily alter the copy command to be
>
>    cp $< $(subst /,_,$@)
>
> but I can't figure out how to generate the list of [ group_d_index.html 
> group_e_index.html] files as a prerequisite.  If I try and use the 
> pattern expansion with a substitute command:
>
> INDEX_HTML_FILES := $(subst /,_,$(DIRECTORIES:%=%_index.html))

Sounds like a great place to use $(eval).  You could do the following:

    DIRECTORIES := a b c group/d group/e

    define copier
    $(subst /,_,$1): $1 ; cp $$< $$@
    endef

    $(foreach d,$(DIRECTORIES),$(eval $(call copier,$d/index.html)))

John.
--
John Graham-Cumming
address@hidden

Home: http://www.jgc.org/
POPFile: http://getpopfile.org/

Sign up for my Spam and Anti-spam Newsletter
at http://www.jgc.org/

PGP key: http://www.jgc.org/pgp/