Make $outputpath relative (fix #24)

Author: rrthomas

Cookbook.nancy.md

@@ -124,7 +124,7 @@ zip -r archive.zip .
 Assuming it is called `make-zip.in.sh`, it can be used thus, from a file called `make-zip.in.nancy`:
 
 ```
-\$run(make-zip.in.sh,\$outputpath)
+\$run(make-zip.in.sh,\$outputpath/\$path)
 ```
 
 ## Processing files in the input directory

README.nancy.md

@@ -144,8 +144,8 @@ Nancy recognises these commands:
   input tree. This is always a template file, unless the current input path
   is a single file.
 + *`\$realpath`* Returns the real path of the file currently being expanded.
-+ *`\$outputpath`* Returns the path of the output for the file currently
-  being expanded.
++ *`\$outputpath`* Returns the path of the output tree for the file currently
+  being expanded, relative to `NANCY_OUTPUT`.
 
 The last two commands are mostly useful in arguments to `\$run`.
 
@@ -205,8 +205,7 @@ When Nancy `\$run`s a program, it sets the following environment variables:
 - NANCY_INPUT - the root of whichever of the input trees contains the file that
   is being expanded: a prefix of `\$realpath`. The file's name, relative to
   `NANCY_INPUT`, is `\$path`.
-
-- NANCY_OUTPUT - the root of the output tree: a prefix of `\$outputpath`.
+- NANCY_OUTPUT - the root of the output tree.
 
 ### Escaping
 

nancy/__init__.py

@@ -269,16 +269,23 @@ def input_file(self):
             raise ValueError("$realpath is not available for directories")
         return self.root / self.path
 
-    def output_file(self):
-        """Returns the (computed) filesystem output `Path`.
+    def output_path(self):
+        """Returns the relative output `Path` for the current file.
 
         Raises an error if called while the filename is being expanded.
         """
         if self._output_path is None:
             raise ValueError(
                 "$outputfile is not available while expanding the filename"
             )
-        return self.trees.output / self._output_path
+        return self._output_path
+
+    def output_file(self):
+        """Returns the (computed) filesystem output `Path`.
+
+        Raises an error if called while the filename is being expanded.
+        """
+        return self.trees.output / self.output_path()
 
     def find_on_path(self, start_path: Path, file: Path) -> Optional[Path]:
         """Search for file starting at the given path.
@@ -458,7 +465,7 @@ def outputpath(self, args: Optional[list[bytes]], input: Optional[bytes]) -> byt
             raise ValueError("$outputpath does not take arguments")
         if input is not None:
             raise ValueError("$outputpath does not take an input")
-        return bytes(self._expand.output_file())
+        return bytes(self._expand.output_path())
 
     def expand(self, args: Optional[list[bytes]], input: Optional[bytes]) -> bytes:
         if args is not None:

tests/test-files/writing-file-to-outputpath-src/write-binary.in.nancy.txt

@@ -1 +1 @@
-$run(sh,-c,printf '\a' > $expand{$run(dirname,$outputpath)}/bell.bin)
+$run(sh,-c,printf '\a' > $expand{$run(dirname,\\$NANCY_OUTPUT/$outputpath)}/bell.bin)