Literate Programming Using OmniMark

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7. Generating Output Filenames

Since handling filenames is typically system-dependent, it is best to centralise it in one place. This code is straightforward. If generate-filename is called from a program element, we use the output attribute to generate a filename. When called from the section element, we can generate an arbitrary filename; here, we use the index of the corresponding item of the weaved-file shelf. Finally, if the call is made from the code element, we use its output attribute as the filename.

define string source function 
 generate-filename
as
 do when element is "program"
 output (attribute "output" drop ([any \ "/"]+ "/")* 
 take any ++ lookahead ("." [any \ "."]+ value-end)) 
 || weaved-filename-suffix
 else when element is "section"
 output "4fzd" % number of weaved-file || weaved-filename-suffix
 else when element is "code"
 output attribute "output"
 else
 not-reached message "ERROR: We shouldn't be generating a filename"
 || " in element %"" || name of element || "%"."
 done
 

As mentioned earlier, it seems easier to split up the weaved files during the weaving process, rather than putting it off to the formatting phase. We end up generating weaved filenames often, but we keep track of it using the weaved-filename shelf.

 set new weaved-filename to generate-filename
 

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