minor fixes to documentation and clang-format integration

docs/usage/generator_scripts.md

@@ -18,19 +18,18 @@ The code generation process in a generator script is controlled by the
 It configures the code generator by combining configuration options from the 
 environment (e.g. a CMake build system) with options specified in the script,
 and infers the names of the output files from the script's name.
-It then prepares a code generation [context][pystencilssfg.SfgContext] and a
-[composer][pystencilssfg.SfgComposer].
-The latter is returned when entering the context manager, and provides a convenient
-interface to constructing the source files.
+It then prepares and returns a code generation [context][pystencilssfg.SfgContext].
+This context may then be passed to a [composer][pystencilssfg.SfgComposer],
+which provides a convenient interface for constructing the source files.
 
 To start, place the following code in a Python script, e.g. `kernels.py`:
 
 ```Python
-from pystencilssfg import SourceFileGenerator, SfgConfiguration
+from pystencilssfg import SourceFileGenerator, SfgConfiguration, SfgComposer
 
 sfg_config = SfgConfiguration()
-with SourceFileGenerator(sfg_config) as sfg:
-    pass
+with SourceFileGenerator(sfg_config) as ctx:
+    sfg = SfgComposer(ctx)
 
 ```
 
@@ -56,9 +55,11 @@ A few notes on configuration:
 
 ## Using the Composer
 
-The object `sfg` returned by the context manager is an [SfgComposer](pystencilssfg.SfgComposer).
-It is a stateless builder object which provides a convenient interface to construct the source
-file's contents. Here's an overview:
+The object `sfg` constructed in above snippet is an instance of [SfgComposer][pystencilssfg.SfgComposer].
+The composer is the central part of the user front-end of *pystencils-sfg*.
+It provides an interface for constructing source files that attempts to closely mimic
+C++ syntactic structures within Python.
+Here is an overview of its various functions:
 
 ### Includes and Definitions
 

src/pystencilssfg/configuration.py

@@ -85,15 +85,6 @@ class SfgCodeStyle:
         prefix = " " * self.indent_width
         return indent(s, prefix)
 
-    def __post__init__(self):
-        if self.force_clang_format:
-            import shutil
-
-            if not shutil.which(self.clang_format_binary):
-                raise SfgException(
-                    "`force_clang_format` set to true in code style, but clang-format binary not found."
-                )
-
 
 @dataclass
 class SfgOutputSpec:

src/pystencilssfg/emission/clang_format.py

@@ -9,7 +9,13 @@ def invoke_clang_format(code: str, codestyle: SfgCodeStyle) -> str:
     args = [codestyle.clang_format_binary, f"--style={codestyle.code_style}"]
 
     if not shutil.which(codestyle.clang_format_binary):
-        return code
+        if codestyle.force_clang_format:
+            raise SfgException(
+                "`force_clang_format` was set to true in code style, "
+                "but clang-format binary could not be found."
+            )
+        else:
+            return code
 
     result = subprocess.run(args, input=code, capture_output=True, text=True)
 

src/pystencilssfg/emission/header_source_pair.py

@@ -4,7 +4,6 @@ from ..configuration import SfgOutputSpec
 from ..context import SfgContext
 from .prepare import prepare_context
 from .printers import SfgHeaderPrinter, SfgImplPrinter
-
 from .clang_format import invoke_clang_format