remove empy support

* Closes #6458
* EmPy support is currently broken.
* As there are no users of this integration and concerns over
  the future of the package, we have decided to drop support
  rather than fixing it.

changes.d/6476.break.md

@@ -0,0 +1 @@
+Remove support for the EmPy template engine.

conda-environment.yml

@@ -21,7 +21,6 @@ dependencies:
   - tomli >=2 # [py<3.11]
 
 # optional dependencies
-  #- empy >=3.3,<3.4
   #- pandas >=1.0,<2
   #- pympler
   #- matplotlib-base

cylc/flow/parsec/exceptions.py

@@ -141,10 +141,6 @@ class TemplateVarLanguageClash(FileParseError):
     """Multiple workflow configuration templating engines configured."""
 
 
-class EmPyError(FileParseError):
-    """Wrapper class for EmPy exceptions."""
-
-
 class Jinja2Error(FileParseError):
     """Wrapper class for Jinja2 exceptions.
 

cylc/flow/parsec/fileparse.py

@@ -258,8 +258,7 @@ def process_plugins(fpath: 'Union[str, Path]', opts: 'Values'):
         'env': A dictionary of environment variables.
         'template_variables': A dictionary of template variables.
         'templating_detected': Where the plugin identifies a templating
-            language this is specified here. Expected values are ``jinja2``
-            or ``empy``.
+            language this is specified here.
 
     args:
         fpath: Path to a config file. Plugin will look at the parent
@@ -446,7 +445,6 @@ def read_and_proc(
         flines = [line.rstrip('\n') for line in f]
 
     do_inline = True
-    do_empy = True
     do_jinja2 = True
     do_contin = True
 
@@ -456,8 +454,6 @@ def read_and_proc(
         template_vars = {}
 
     if viewcfg:
-        if not viewcfg['empy']:
-            do_empy = False
         if not viewcfg['jinja2']:
             do_jinja2 = False
         if not viewcfg['contin']:
@@ -479,27 +475,6 @@ def read_and_proc(
     process_with = hashbang_and_plugin_templating_clash(
         extra_vars[TEMPLATING_DETECTED], flines
     )
-    # process with EmPy
-    if do_empy:
-        if (
-            extra_vars[TEMPLATING_DETECTED] == 'empy' and
-            not process_with and
-            process_with != 'empy'
-        ):
-            flines.insert(0, '#!empy')
-
-        if flines and re.match(r'^#![Ee]m[Pp]y\s*', flines[0]):
-            LOG.debug('Processing with EmPy')
-            try:
-                from cylc.flow.parsec.empysupport import empyprocess
-            except ImportError:
-                raise ParsecError(
-                    'EmPy Python package must be installed '
-                    'to process file: ' + fpath
-                ) from None
-            flines = empyprocess(
-                fpath, flines, fdir, template_vars
-            )
 
     # process with Jinja2
     if do_jinja2:
@@ -546,8 +521,7 @@ def hashbang_and_plugin_templating_clash(
         flines: The lines of text from file.
 
     Returns:
-        The hashbang, in lower case, to allow for users using any of
-        ['empy', 'EmPy', 'EMPY'], or similar in other templating languages.
+        The hashbang, in lower case.
 
     Examples:
         - Hashbang and templating_detected match:
@@ -559,7 +533,7 @@ def hashbang_and_plugin_templating_clash(
             >>> thisfunc('', [''])
 
         - Function raises if templating engines clash:
-            >>> thisfunc('empy', ['#!jinja2'])
+            >>> thisfunc('other', ['#!jinja2'])
             Traceback (most recent call last):
                 ...
             cylc.flow.parsec.exceptions.TemplateVarLanguageClash: ...

cylc/flow/scripts/lint.py

@@ -421,8 +421,6 @@ def check_indentation(line: str) -> bool:
         | <[^>]+>
         # or Jinja2
         | {{.*?}} | {%.*?%} | {\#.*?\#}
-        # or EmPy
-        | (@[\[{\(]).*([\]\}\)])
     ''',
     re.X
 )

cylc/flow/scripts/view.py

@@ -21,7 +21,7 @@
 Print a processed workflow configuration.
 
 Print workflow configurations as processed before full parsing by Cylc. This
-includes Jinja2 or Empy template processing, and inlining of include-files.
+includes Jinja2 template processing, and inlining of include-files.
 Some explanatory markup may also be requested.
 
 Warning:
@@ -63,12 +63,6 @@ def get_option_parser():
         "--inline", "-i", help="Inline include-files.", action="store_true",
         default=False, dest="inline")
 
-    parser.add_option(
-        "--empy", "-e",
-        help="View after EmPy template processing "
-             "(implies '-i/--inline' as well).",
-        action="store_true", default=False, dest="empy")
-
     parser.add_option(
         "--jinja2", "-j",
         help="View after Jinja2 template processing "
@@ -77,7 +71,7 @@ def get_option_parser():
 
     parser.add_option(
         "-p", "--process",
-        help="View after all processing (EmPy, Jinja2, inlining, "
+        help="View after all processing (Jinja2, inlining, "
              "line-continuation joining).",
         action="store_true", default=False, dest="process")
 
@@ -138,13 +132,9 @@ async def _main(options: 'Values', workflow_id: str) -> None:
             'mark': options.mark,
             'single': options.single,
             'label': options.label,
-            'empy': options.empy or options.process,
             'jinja2': options.jinja2 or options.process,
             'contin': options.cat or options.process,
-            'inline': (
-                options.jinja2 or options.empy or
-                options.inline or options.process
-            ),
+            'inline': options.inline or options.process,
         },
         opts=options,
     ):

pytest.ini

@@ -23,7 +23,6 @@ addopts = --verbose
     --dist=loadscope
     # ignore files which cause issues with test collection
     --ignore=cylc/flow/data_messages_pb2.py
-    --ignore=cylc/flow/parsec/empysupport.py
     --ignore=cylc/flow/parsec/example
     # disable pytest-tornasync because it conflicts with pytest-asyncio's auto mode
     -p no:tornado

setup.cfg

@@ -86,8 +86,6 @@ install_requires =
 include = cylc*
 
 [options.extras_require]
-empy =
-    EmPy==3.3.*
 graph =
     pillow
 main_loop-log_data_store =
@@ -137,7 +135,6 @@ tutorials =
     pillow
     requests
 all =
-    %(empy)s
     %(graph)s
     %(main_loop-log_data_store)s
     %(main_loop-log_db)s