Render to stdout by default (#5)

docs/stack_diff.html

@@ -208,23 +208,23 @@ <h1>Python usage<a class="headerlink" href="#python-usage" title="Permalink to t
 </dd></dl>
 <dl class="py method">
 <dt class="sig sig-object py" id="stackdiff.StackDiff.render_changes">
-<span class="sig-name descname"><span class="pre">render_changes</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">writer</span></span><span class="p"><span class="pre">:</span></span> <span class="n"><span class="pre">IO</span><span class="p"><span class="pre">[</span></span><span class="pre">str</span><span class="p"><span class="pre">]</span></span></span></em><span class="sig-paren">)</span> <span class="sig-return"><span class="sig-return-icon">→</span> <span class="sig-return-typehint"><span class="pre">None</span></span></span><a class="headerlink" href="#stackdiff.StackDiff.render_changes" title="Permalink to this definition">¶</a></dt>
+<span class="sig-name descname"><span class="pre">render_changes</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">writer</span></span><span class="p"><span class="pre">:</span></span> <span class="n"><span class="pre">Optional</span><span class="p"><span class="pre">[</span></span><span class="pre">IO</span><span class="p"><span class="pre">[</span></span><span class="pre">str</span><span class="p"><span class="pre">]</span></span><span class="p"><span class="pre">]</span></span></span> <span class="o"><span class="pre">=</span></span> <span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span> <span class="sig-return"><span class="sig-return-icon">→</span> <span class="sig-return-typehint"><span class="pre">None</span></span></span><a class="headerlink" href="#stackdiff.StackDiff.render_changes" title="Permalink to this definition">¶</a></dt>
 <dd><p>Renders a visualisation of the changes that CloudFormation would apply
 if the change set was executed.</p>
 <dl class="field-list simple">
 <dt class="field-odd">Parameters</dt>
-<dd class="field-odd"><p><strong>writer</strong> – Writer</p>
+<dd class="field-odd"><p><strong>writer</strong> – Writer (defaults to <code class="docutils literal notranslate"><span class="pre">stdout</span></code>)</p>
 </dd>
 </dl>
 </dd></dl>
 <dl class="py method">
 <dt class="sig sig-object py" id="stackdiff.StackDiff.render_differences">
-<span class="sig-name descname"><span class="pre">render_differences</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">writer</span></span><span class="p"><span class="pre">:</span></span> <span class="n"><span class="pre">IO</span><span class="p"><span class="pre">[</span></span><span class="pre">str</span><span class="p"><span class="pre">]</span></span></span></em><span class="sig-paren">)</span> <span class="sig-return"><span class="sig-return-icon">→</span> <span class="sig-return-typehint"><span class="pre">None</span></span></span><a class="headerlink" href="#stackdiff.StackDiff.render_differences" title="Permalink to this definition">¶</a></dt>
+<span class="sig-name descname"><span class="pre">render_differences</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">writer</span></span><span class="p"><span class="pre">:</span></span> <span class="n"><span class="pre">Optional</span><span class="p"><span class="pre">[</span></span><span class="pre">IO</span><span class="p"><span class="pre">[</span></span><span class="pre">str</span><span class="p"><span class="pre">]</span></span><span class="p"><span class="pre">]</span></span></span> <span class="o"><span class="pre">=</span></span> <span class="default_value"><span class="pre">None</span></span></em><span class="sig-paren">)</span> <span class="sig-return"><span class="sig-return-icon">→</span> <span class="sig-return-typehint"><span class="pre">None</span></span></span><a class="headerlink" href="#stackdiff.StackDiff.render_differences" title="Permalink to this definition">¶</a></dt>
 <dd><p>Renders a visualisation of the differences between the stack’s current
 template and the change set’s proposed template.</p>
 <dl class="field-list simple">
 <dt class="field-odd">Parameters</dt>
-<dd class="field-odd"><p><strong>writer</strong> – Writer</p>
+<dd class="field-odd"><p><strong>writer</strong> – Writer (defaults to <code class="docutils literal notranslate"><span class="pre">stdout</span></code>)</p>
 </dd>
 </dl>
 </dd></dl>

stackdiff/stack_diff.py

@@ -1,4 +1,5 @@
 from functools import cached_property
+from sys import stdout
 from typing import IO, Optional
 
 from ansiscape import green, heavy, yellow
@@ -57,13 +58,13 @@ def change_template(self) -> str:
         )
         return response.get("TemplateBody", "")
 
-    def render_changes(self, writer: IO[str]) -> None:
+    def render_changes(self, writer: Optional[IO[str]] = None) -> None:
         """
         Renders a visualisation of the changes that CloudFormation would apply
         if the change set was executed.
 
         Arguments:
-            writer: Writer
+            writer: Writer (defaults to ``stdout``)
         """
 
         response = self.client.describe_change_set(
@@ -109,18 +110,18 @@ def render_changes(self, writer: IO[str]) -> None:
             )
 
         t = tabulate(rows, headers="firstrow", tablefmt="plain")
-        writer.write(t + "\n")
+        (writer or stdout).write(t + "\n")
 
-    def render_differences(self, writer: IO[str]) -> None:
+    def render_differences(self, writer: Optional[IO[str]] = None) -> None:
         """
         Renders a visualisation of the differences between the stack's current
         template and the change set's proposed template.
 
         Arguments:
-            writer: Writer
+            writer: Writer (defaults to ``stdout``)
         """
 
-        render(self.stack_template, self.change_template, writer)
+        render(self.stack_template, self.change_template, writer or stdout)
 
     @cached_property
     def stack_template(self) -> str: