add filter for passing lists of strings (#30)

hissw/environment.py

@@ -9,6 +9,7 @@
 
 import jinja2
 from scipy.io import readsav
+from .filters import string_list_filter
 
 from .read_config import defaults
 from .util import SSWIDLError, IDLLicenseError
@@ -34,7 +35,7 @@ class Environment(object):
     idl_home : `str`, optional
         Path to IDL executable
     filters : `dict`, optional
-        Filters to use scripts. This should be a dictionary where the key
+        Filters to use in scripts. This should be a dictionary where the key
         is the name of the filter and the value is the corresponding
         function.
     idl_only : `bool`, optional
@@ -57,6 +58,7 @@ def __init__(self, ssw_packages=None, ssw_paths=None, extra_paths=None,
         self.env = jinja2.Environment(loader=jinja2.PackageLoader('hissw', 'templates'))
         self.env.filters['to_unit'] = units_filter
         self.env.filters['log10'] = log10_filter
+        self.env.filters['string_list'] = string_list_filter
         if filters is not None:
             for k, v in filters.items():
                 self.env.filters[k] = v

hissw/filters.py

@@ -21,3 +21,13 @@ def log10_filter(value):
     Take the base 10 log of a given value.
     """
     return np.log10(value)
+
+
+def string_list_filter(string_list):
+    """
+    Double quote a list of strings.
+    
+    This is needed when passing in a list of strings to IDL as each string
+    in the list will not be quoted when passed into the template.
+    """
+    return [f"'{s}'" for s in string_list]

hissw/tests/test_hissw.py

@@ -115,6 +115,15 @@ def test_log10_filter(idl_env):
     assert res['foo'] == np.log10(foo)
 
 
+def test_string_list_filter(idl_env):
+    script = """
+    foo = {{ foo | string_list }}
+    """
+    foo = ['my', 'list', 'of', 'strings']
+    res = idl_env.run(script, args={'foo': foo})
+    assert [v.decode('utf-8') for v in res['foo']] == [f"'{f}'" for f in foo]
+
+
 def test_default_ssw_var(ssw_env):
     script = """
     foo = '{{ ssw_home }}'