Style patches

A highlighting style can be patched by modifiying the highlighting associated to one or more element categories or subcategories, thus allowing a certain form of "highlighting inside the highlighting", which can be very useful in a number of contexts, like teaching, or when preparing technical demos.

::Method methodName
  -- In this code fragment, the standard dark mode highlighting style is used.
  -- Additionally, local variables are specially highlighted with a bold black
  -- font over a yellow background, and the highlighting for method names is
  -- modified to have a black foreground over a magenta background.
  len = Length("String")
  n   = Pos("x", value)

Patches can be specified as an optional argument of the parse method of the Highlighter class, or as attributes of a fenced code block.

Patches and code blocks

Inine patches

Style patches can be specified inline using the patch= attribute of the rexx fenced code block marker. As an example, here is the source for the above code block:

```rexx {patch="n method #000/#c0c; element Simple_Variable #000/#cc0 bold"}
::Method methodName
  -- In this code fragment, the standard dark mode highlighting style is used.
  -- Additionally, local variables are specially highlighted with a bold black
  -- font over a yellow background, and the highlighting for method names is
  -- modified to have a black foreground over a magenta background.
  len = Length("String")
  n   = Pos("x", value)
```

External patch files

You can also use the patchfile= attribute to specify a filename where the style patch resides:

```rexx {patchfile=filename}
(code block to patch)
```