Merge pull request #4 from michalpokusa/template-syntax-error-rework

Reworked errors in template syntax and overall more validation, caching by default

Author: FoamyGuy

adafruit_templateengine.py

@@ -6,4 +6,3 @@
 
 .. automodule:: adafruit_templateengine
     :members:
-    :inherited-members:

docs/api.rst

@@ -9,30 +9,28 @@ This example is printing a basic HTML page with with a dynamic paragraph.
     :lines: 5-
     :linenos:
 
-Reusing templates
------------------
+Caching/Reusing templates
+-------------------------
 
-The are two main ways of rendering templates:
+The are two ways of rendering templates:
 
+- manually creating a ``Template`` or ``FileTemplate`` object and calling its method
 - using one of ``render_...`` methods
-- manually creating a ``Template`` object and calling its method
 
-While the first method is simpler, it also compiles the template on every call.
-The second method is more efficient when rendering the same template multiple times, as it allows
-to reuse the compiled template, at the cost of more memory usage.
 
-Both methods can be used interchangeably, as they both return the same result.
-It is up to the user to decide which method is more suitable for a given use case.
+By dafault, the ``render_...`` methods cache the template and reuse it on next calls.
+This speeds up the rendering process, but also uses more memory.
 
-**Generally, the first method will be sufficient for most use cases.**
+If for some reason the caching is not desired, you can disable it by passing ``cache=False`` to
+the ``render_...`` method. This will cause the template to be recreated on every call, which is slower,
+but uses less memory. This might be useful when rendering a large number of different templates that
+might not fit in the memory at the same time or are not used often enough to justify caching them.
 
-It is also worth noting that compiling all used templates using the second method might not be possible,
-depending on the project and board used, due to the limited amount of RAM.
 
 .. literalinclude:: ../examples/templateengine_reusing.py
     :caption: examples/templateengine_reusing.py
     :lines: 5-
-    :emphasize-lines: 1,16,20
+    :emphasize-lines: 22,27,34
     :linenos:
 
 Expressions
@@ -234,29 +232,20 @@ Autoescaping unsafe characters
 ------------------------------
 
 Token ``{% autoescape off %} ... {% endautoescape %}`` is used for marking a block of code that should
-be not be autoescaped. Consequently using ``{% autoescape off %} ...`` does the opposite and turns
+be not be autoescaped. Consequently using ``{% autoescape on %} ...`` does the opposite and turns
 the autoescaping back on.
 
 By default the template engine will escape all HTML-unsafe characters in expressions
 (e.g. ``<`` will be replaced with ``&lt;``).
 
 Content outside expressions is not escaped and is rendered as-is.
 
-For escaping XML and Markdown, you can use the ``language=`` parameter, both in ``render_...`` methods
-and in all ``Template`` constructors.
-
 .. literalinclude:: ../examples/autoescape.html
     :caption: examples/autoescape.html
     :lines: 7-
     :language: html
     :linenos:
 
-.. literalinclude:: ../examples/autoescape.md
-    :caption: examples/autoescape.md
-    :lines: 5-
-    :language: markdown
-    :linenos:
-
 .. literalinclude:: ../examples/templateengine_autoescape.py
     :caption: examples/templateengine_autoescape.py
     :lines: 5-

docs/examples.rst

@@ -22,7 +22,7 @@
         This is a {{ "<b>bold text</b>" }}, because autoescaping is turned off in this block.
 
         {% autoescape on %}
-            And againg, this is not a {{ "<b>bold text</b>" }},
+            And again, this is not a {{ "<b>bold text</b>" }},
             because in this block autoescaping is turned on again.
         {% endautoescape %}
     {% endautoescape %}

examples/autoescape.html

@@ -2,12 +2,7 @@
 #
 # SPDX-License-Identifier: Unlicense
 
-from adafruit_templateengine import render_template, Language
+from adafruit_templateengine import render_template
 
-# By default autoescape is enabled for HTML
-print("HTML autoescape:")
+# By default autoescape is enabled for HTML entities
 print(render_template("./examples/autoescape.html"))
-
-# But XML and Markdown are also supported
-print("Markdown autoescape:")
-print(render_template("./examples/autoescape.md", language=Language.MARKDOWN))

examples/autoescape.md

@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: Unlicense
 
-from adafruit_templateengine import Template
+from adafruit_templateengine import Template, render_string
 
 
 template_string = r"""
@@ -17,8 +17,28 @@
 </html>
 """
 
-template = Template(template_string)
+other_template_string = r"""
+<footer>
+    <p>Goodbye, {{ context.get("name") or "Anonymous User" }}!</p>
+</footer>
+"""
+
+# Manually create a Template object
+template = Template(template_string)  # Creates a template object
+print(template.render({"name": "John"}))  # Reuses the Template object
+print(template.render({"name": "Alex"}))  # Reuses the Template object
+
+# Using the `render_string` function
+print(
+    render_string(template_string, {"name": "John"})
+)  # Creates a new Template object and saves it
+print(render_string(template_string, {"name": "Alex"}))  # Reuses the Template object
 
-context = {"name": ""}  # Put your name here
 
-print(template.render(context))
+# Using the `render_string` function, but without caching
+print(
+    render_string(other_template_string, {"name": "John"}, cache=False)
+)  # Creates a new Template object and does not save it
+print(
+    render_string(other_template_string, {"name": "Alex"}, cache=False)
+)  # Creates a new Template object a second time and does not save it

examples/templateengine_autoescape.py

@@ -29,7 +29,6 @@ keywords = [
     "substitution",
     "web",
     "html",
-    "xml",
     "escaping",
     "syntax",
 ]