Reduce use of "if defined(argument)"

setup.py

@@ -21,7 +21,9 @@
     author_email="[email protected]",
     license="GNU",
     packages=["wdlgen"],
-    install_requires=[],
+    install_requires=[
+        'miniwdl'
+    ],
     zip_safe=False,
     long_description=long_description,
     long_description_content_type="text/markdown",

tests/test_task_generation.py

@@ -13,6 +13,20 @@
     ParameterMeta,
 )
 
+import WDL
+from WDL._parser import _ExprTransformer, parse, _grammar
+
+
+def parse_miniwdl_token(token: str, text: str, version: bool = None):
+    """
+    Uses miniWDL to parse some fragment of WDL
+
+    :param token: The name of the WDL token to parse. Refer to
+        https://github.com/chanzuckerberg/miniwdl/blob/master/WDL/_grammar.py for a complete list
+    :param text: The text to parse as WDL
+    :param version: "1.0" (default) or "draft-2"
+    """
+    return _ExprTransformer().transform(parse(_grammar.get(version)[0], text, token))
 
 class TestTaskGeneration(unittest.TestCase):
     def test_simple_task(self):
@@ -60,27 +74,6 @@ def test_readme_task(self):
         # command in next section
         t.outputs.append(Output(WdlType.parse_type("File"), "standardOut", "stdout()"))
 
-        command = Task.Command("echo")
-        command.inputs.append(
-            Task.Command.CommandInput(
-                "taskGreeting",
-                optional=False,
-                position=None,
-                prefix="-a",
-                separate_value_from_prefix=True,
-                default=None,
-            )
-        )
-        command.inputs.append(
-            Task.Command.CommandInput(
-                "otherInput",
-                optional=True,
-                position=2,
-                prefix="optional-param=",
-                separate_value_from_prefix=False,
-                default=None,
-            )
-        )
         command = Task.Command("echo")
         command.inputs.append(
             Task.Command.CommandInput(
@@ -164,12 +157,16 @@ def test_readme_example(self):
                 default=None,
             )
         )
-        expected = """\
+        output = command.get_string()
+        expected = '''\
 echo \\
   -a ~{taskGreeting} \\
-  ~{if defined(otherInput) then ('"' + "optional-param=" + otherInput + '"') else ""}"""
+  ~{'"optional-param=' + otherInput + '"'}'''
         # t is the task
-        self.assertEqual(expected, command.get_string())
+        self.assertEqual(expected, output)
+
+        # Check that it's also valid WDL
+        parse_miniwdl_token('command2', 'command <<<\n' + output + '\n>>>')
 
     def test_commandinput_space(self):
         t = Task.Command.CommandInput(

wdlgen/task.py

@@ -117,8 +117,8 @@ def get_string(self):
                     self.false,
                 )
 
-                pr = self.prefix if self.prefix else ""
-                bc = pr + (" " if self.separate and self.prefix else "")
+                prefix = self.prefix if self.prefix else ""
+                bc = prefix + (" " if self.separate and self.prefix else "")
 
                 if self.separate_arrays:
                     if array_sep or default or true or false:
@@ -154,16 +154,12 @@ def get_string(self):
                     options.append(f'false="{false if false else ""}"')
 
                 stroptions = "".join(o + " " for o in options)
-
-                prewithquotes = f'"{bc}" + ' if bc.strip() else ""
-                if self.optional and not default and not is_flag and prewithquotes:
+                if self.optional and not default and not is_flag and bc.strip():
                     # Option 1: We apply quotes are value, Option 2: We quote whole "prefix + name" combo
-                    full_token = (
-                        f"{prewithquotes} '\"' + {name} + '\"'"
-                        if (self.separate and self.prefix and prewithquotes)
-                        else f"'\"' + {prewithquotes}{name} + '\"'"
-                    )
-                    return f'~{{{stroptions}if defined({name}) then ({full_token}) else ""}}'
+                    if self.separate and self.prefix:
+                        return f'~{{\'"{prefix}" "\' + {name} + \'"\'}}'
+                    else:
+                        return f'~{{\'"{prefix}\' + {name} + \'"\'}}'
                 else:
                     return bc + f"~{{{stroptions}{name}}}"