Require -x to use tags not in a builtin hardcoded list.

examples/format.gamebook.options

@@ -0,0 +1 @@
+-x

formatgamebook.py

@@ -70,8 +70,9 @@ def format_gamebook(inputfilenames,
                     shuffle,
                     includetags,
                     excludetags,
-                    mapfilenames):
-    output_format = make_output(outputfilename, templatedirs)
+                    mapfilenames,
+                    allow_unknown_tags):
+    output_format = make_output(outputfilename, allow_unknown_tags, templatedirs)
     book = sections.Book(make_bookid(outputfilename), includetags, excludetags)
     for inputfilename in inputfilenames:
         parse_file_to_book(open(inputfilename, 'r'), output_format.name, book)
@@ -153,11 +154,12 @@ def add_section_to_book(book, name, text, intro_section=False,
         if number:
             book.force_section_nr(name, number)
 
-def make_output(outputfilename, templatedirs):
+def make_output(outputfilename, allow_unknown_tags, templatedirs):
     for of in OUTPUT_FORMATS:
         extension = of['extension']
         if outputfilename.endswith('.' + extension):
             return OutputFormat(templates.Templates(templatedirs, extension),
+                                allow_unknown_tags,
                                 of['quote'], extension.upper())
     raise Exception("Unsupported or unknown output format for %s."
                     % outputfilename)
@@ -220,6 +222,8 @@ if __name__ == '__main__':
                     help='do not shuffle sections')
     ap.add_argument('-m', '--map-file', metavar='F', dest='mapfiles',
                     action='append', help='number map file')
+    ap.add_argument('-x', '--allow-unknown', action='store_true',
+                    dest='allow_unknown_tags')
     args = ap.parse_args()
     templatedirs = ['templates',
                     os.path.join(os.path.dirname(sys.argv[0]), 'templates')]
@@ -237,4 +241,5 @@ if __name__ == '__main__':
                     args.shuffle,
                     args.includetags or [],
                     args.excludetags or [],
-                    args.mapfiles or [])
+                    args.mapfiles or [],
+                    args.allow_unknown_tags)

output.py

@@ -2,14 +2,41 @@ import os
 import os.path
 import sys
 
+# Hardcoded list of tags allowed without -x flag.
+BUILTIN_TAGS = ['add',
+                'atleast',
+                'b',
+                'collect',
+                'cost',
+                'count',
+                'dec',
+                'drop',
+                'found',
+                'has',
+                'hasnot',
+                'img',
+                'inc',
+                'init',
+                'lessthan',
+                'min',
+                'morethan',
+                'random',
+                'set',
+                'take',
+                'trade',
+                'xor']
+
+NOT_BUILTIN_TAG_MESSAGE = "Unknown tag %s not allowed without -x flag."
+
 COUNTER_CREATE_TAG = 'count'
 COUNTER_USE_TAGS = set(['set', 'inc', 'dec', 'min',
                         'lessthan', 'morethan', 'atleast'])
 
 class OutputFormat (object):
     "Handles book output. Big FIXME required to make sense."
-    def __init__(self, templates, quote, name):
+    def __init__(self, templates, allow_unknown_tags, quote, name):
         self.templates = templates
+        self.allow_unknown_tags = allow_unknown_tags
         self.format_quote = quote
         self.name = name
         self.counter_names = {}
@@ -112,6 +139,8 @@ class OutputFormat (object):
                 tag = section.text[tag_start+1:tag_end].strip()
                 tagparts = tag.split()
                 tagname = tagparts[0]
+                if not self.allow_unknown_tags and tagname not in BUILTIN_TAGS:
+                    raise Exception(NOT_BUILTIN_TAG_MESSAGE % tagname)
                 end_tag_start = section.text.find('[', tag_end)
                 if (not end_tag_start > tag_end
                     and section.text[end_tag_start].startswith('[/' + tagname

readme.org

@@ -19,6 +19,7 @@ gamebook on paper or a screen (or for debugging it).
 :   -o D, --option D      add template override options dir
 :   -S, --no-shuffle      do not shuffle sections
 :   -m F, --map-file F    number map file
+:   -x, --allow_unknown   allow unknown tags
 ** Supported Output Formats
 
 | Name             | Extension | Description                                                                                   |
@@ -56,6 +57,26 @@ todo (or substitute whatever other tag(s) you are interested in).
 | static   | html    | Remove script link from HTML output.            |
 | twine2   | html    | Generate story that can be imported to [[http://twinery.org/2/#stories][Twine 2]]  |
 
+** Adding Custom Templates
+Any of the built-in templates can be overridden easily. New
+tags can be added that can generate any output you need for
+different file formats. However to add a tag that is not
+included in the default distribution the command-line
+flat *-x* is required to tell gamebookformat that you
+know what you are doing. Otherwise when an unknown
+tag is encountered you get an ugly error message.
+The reason for making it moderately difficult to add
+a new tag is that all the builtin tags have been
+choosen to work reasonably well in anything from
+static printed gamebooks to dynamic digital app
+gamebooks. Anyone thinking of adding a new tag
+should think twice about how having that tag might
+mean that some output formats are not longer useful.
+Sticking to the default tags and not overriding them
+to do bad things ensures that your gamebooks are
+still readable and playable in all supported
+output formats. (The process of adding new templates and new output
+formats really should be better documented.)
 ** Styles and Scripts
 Generated *html* files use the included *gamebookformat.css* for
 styling and *gamebookformat.js* for scripting (except with the

test_output.py

@@ -20,10 +20,10 @@ class TestOutputFormat(TestCase):
         pass
 
     def test_create(self):
-        of = output.OutputFormat(FakeTemplates({}), "TEST", str)
+        of = output.OutputFormat(FakeTemplates({}), "TEST", False, str)
 
     def test_format_begin(self):
-        of = output.OutputFormat(FakeTemplates({'begin' : 'b %(max)d'}), "TEST", str)
+        of = output.OutputFormat(FakeTemplates({'begin' : 'b %(max)d'}), "TEST", False, str)
         self.assertEqual(of.format_begin({'max' : 2}), 'b 2')
 
 class TestReferenceFormatter(TestCase):