Limit generated components to 250 explicit args by default

configurable to any other number
Keep this to 253 or below for Py3.6 support

Author: alexcjohnson

.gitignore

@@ -73,6 +73,7 @@ npm-debug*
 dash_generator_test_component_standard/
 dash_generator_test_component_nested/
 dash_test_components/
+dash_generator_test_component_typescript/
 inst/
 man/
 R/

@plotly/dash-generator-test-component-standard/package.json

@@ -10,7 +10,7 @@
   "scripts": {
     "build:js": "webpack --mode production",
     "setup": "python setup.py sdist",
-    "build:py_and_r": "dash-generate-components ./src/components dash_generator_test_component_standard && cp base/** dash_generator_test_component_standard/ && dash-generate-components ./src/components dash_generator_test_component_standard --r-prefix 'dgtc_standard'",
+    "build:py_and_r": "dash-generate-components ./src/components dash_generator_test_component_standard && cp base/** dash_generator_test_component_standard/ && dash-generate-components ./src/components dash_generator_test_component_standard --r-prefix 'dgtc_standard' --max-props 2",
     "build": "run-s build:js build:py_and_r setup"
   },
   "author": "Chris Parmer <[email protected]>",

dash/development/_py_components_generation.py

@@ -9,9 +9,14 @@
 from .base_component import Component
 
 
-# pylint: disable=unused-argument
+# pylint: disable=unused-argument,too-many-locals
 def generate_class_string(
-    typename, props, description, namespace, prop_reorder_exceptions=None
+    typename,
+    props,
+    description,
+    namespace,
+    prop_reorder_exceptions=None,
+    max_props=None,
 ):
     """Dynamically generate class strings to have nicely formatted docstrings,
     keyword arguments, and repr.
@@ -56,7 +61,7 @@ def __init__(self, {default_argtext}):
             {list_of_valid_wildcard_attr_prefixes}
         _explicit_args = kwargs.pop('_explicit_args')
         _locals = locals()
-        _locals.update(kwargs)  # For wildcard attrs
+        _locals.update(kwargs)  # For wildcard attrs and excess named props
         args = {{k: _locals[k] for k in _explicit_args if k != 'children'}}
         for k in {required_props}:
             if k not in args:
@@ -91,18 +96,27 @@ def __init__(self, {default_argtext}):
     else:
         default_argtext = ""
         argtext = "**args"
-    default_argtext += ", ".join(
-        [
-            (
-                f"{p:s}=Component.REQUIRED"
-                if props[p]["required"]
-                else f"{p:s}=Component.UNDEFINED"
+    default_arglist = [
+        (
+            f"{p:s}=Component.REQUIRED"
+            if props[p]["required"]
+            else f"{p:s}=Component.UNDEFINED"
+        )
+        for p in prop_keys
+        if not p.endswith("-*") and p not in python_keywords and p != "setProps"
+    ]
+
+    if max_props:
+        final_max_props = max_props - (1 if "children" in props else 0)
+        if len(default_arglist) > final_max_props:
+            default_arglist = default_arglist[:final_max_props]
+            docstring += (
+                "\n\nNote: due to the large number of props for this component,"
+                "\nnot all of them appear in the constructor signature, but"
+                "\nthey may still be used as keyword arguments."
             )
-            for p in prop_keys
-            if not p.endswith("-*") and p not in python_keywords and p != "setProps"
-        ]
-        + ["**kwargs"]
-    )
+
+    default_argtext += ", ".join(default_arglist + ["**kwargs"])
     required_args = required_props(filtered_props)
     return c.format(
         typename=typename,
@@ -118,7 +132,12 @@ def __init__(self, {default_argtext}):
 
 
 def generate_class_file(
-    typename, props, description, namespace, prop_reorder_exceptions=None
+    typename,
+    props,
+    description,
+    namespace,
+    prop_reorder_exceptions=None,
+    max_props=None,
 ):
     """Generate a Python class file (.py) given a class string.
     Parameters
@@ -138,7 +157,7 @@ def generate_class_file(
     )
 
     class_string = generate_class_string(
-        typename, props, description, namespace, prop_reorder_exceptions
+        typename, props, description, namespace, prop_reorder_exceptions, max_props
     )
     file_name = f"{typename:s}.py"
 

dash/development/base_component.py

@@ -138,7 +138,7 @@ def __init__(self, **kwargs):
                     + " detected a Component for a prop other than `children`\n"
                     + f"Prop {k} has value {v!r}\n\n"
                     + "Did you forget to wrap multiple `children` in an array?\n"
-                    + "For example, it must be html.Div([\"a\", \"b\", \"c\"]) not html.Div(\"a\", \"b\", \"c\")\n"
+                    + 'For example, it must be html.Div(["a", "b", "c"]) not html.Div("a", "b", "c")\n'
                 )
 
             if k == "id":

dash/development/component_generator.py

@@ -48,6 +48,7 @@ def generate_components(
     jlprefix=None,
     metadata=None,
     keep_prop_order=None,
+    max_props=None,
 ):
 
     project_shortname = project_shortname.replace("-", "_").rstrip("/\\")
@@ -97,7 +98,17 @@ def generate_components(
 
         metadata = safe_json_loads(out.decode("utf-8"))
 
-    generator_methods = [generate_class_file]
+    py_generator_kwargs = {}
+    if keep_prop_order is not None:
+        keep_prop_order = [
+            component.strip(" ") for component in keep_prop_order.split(",")
+        ]
+        py_generator_kwargs["prop_reorder_exceptions"] = keep_prop_order
+
+    if max_props:
+        py_generator_kwargs["max_props"] = max_props
+
+    generator_methods = [functools.partial(generate_class_file, **py_generator_kwargs)]
 
     if rprefix is not None or jlprefix is not None:
         with open("package.json", "r") as f:
@@ -122,14 +133,6 @@ def generate_components(
             functools.partial(generate_struct_file, prefix=jlprefix)
         )
 
-    if keep_prop_order is not None:
-        keep_prop_order = [
-            component.strip(" ") for component in keep_prop_order.split(",")
-        ]
-        generator_methods[0] = functools.partial(
-            generate_class_file, prop_reorder_exceptions=keep_prop_order
-        )
-
     components = generate_classes_files(project_shortname, metadata, *generator_methods)
 
     with open(os.path.join(project_shortname, "metadata.json"), "w") as f:
@@ -221,6 +224,16 @@ def component_build_arg_parser():
         "props. Pass the 'ALL' keyword to have every component retain "
         "its original prop order.",
     )
+    parser.add_argument(
+        "--max-props",
+        type=int,
+        default=250,
+        help="Specify the max number of props to list in the component signature. "
+        "More props will still be shown in the docstring, and will still work when "
+        "provided as kwargs to the component. Python <3.7 only supports 255 args, "
+        "but you may also want to reduce further for improved readability at the "
+        "expense of auto-completion for the later props. Use 0 to include all props.",
+    )
     return parser
 
 
@@ -237,6 +250,7 @@ def cli():
         rsuggests=args.r_suggests,
         jlprefix=args.jl_prefix,
         keep_prop_order=args.keep_prop_order,
+        max_props=args.max_props,
     )
 
 

tests/integration/test_generation.py

@@ -1,3 +1,5 @@
+import pytest
+
 from dash import Dash, Input, Output
 from dash.exceptions import PreventUpdate
 
@@ -19,6 +21,9 @@ def test_gene001_simple_callback(dash_duo):
 
     app.layout = Div(
         [
+            # Note: `value` is not part of the explicit function signature
+            # for MyStandardComponent, due to --max-props 2 in its build command
+            # but this verifies that it still works.
             MyStandardComponent(id="standard", value="Standard"),
             MyNestedComponent(id="nested", value="Nested"),
             TypeScriptComponent(id="typescript", required_string="TypeScript"),
@@ -72,3 +77,20 @@ def update_container(n_clicks):
     )
 
     dash_duo.percy_snapshot(name="gene002-arbitrary-resource")
+
+
+def test_gene003_max_props():
+    limited_props_doc = "large number of props for this component"
+    # dash_generator_test_component_standard has max_props set to 2, so
+    # MyStandardComponent gets the restricted signature and note about it
+    # in its docstring.
+    # dash_generator_test_component_nested and MyNestedComponent do not.
+    assert limited_props_doc in MyStandardComponent.__doc__
+    assert limited_props_doc not in MyNestedComponent.__doc__
+
+    # Verify that it still works to check for invalid props in both cases
+    with pytest.raises(TypeError):
+        MyStandardComponent(valuex="nope")
+
+    with pytest.raises(TypeError):
+        MyNestedComponent(valuey="nor this")