Only import what's needed.

diff --git a/bookmaker.py b/bookmaker.py
index b60576de6bd8794b4e60f066dcf38acdd5c48fcf..66cc6b3f3bbdfa67556e0892dd817463c61df07c 100755 (executable)
--- a/bookmaker.py
+++ b/bookmaker.py
@@ -4,10 +4,14 @@ bookmaker.py helps optimizing PDFs for the production of small self-printed,
 self-bound physical books; towards this goal offers various PDF manipulation
 options that may also be used indepéndently and for other purposes.
 """
-import argparse
-import io
-import os
-import sys
+from argparse import (
+        ArgumentParser,
+        Namespace as ArgsNamespace,
+        RawDescriptionHelpFormatter
+        )
+from io import BufferedReader, BytesIO
+from os.path import isfile
+from sys import exit as sys_exit
 from typing import Any, Optional
 
 
@@ -16,7 +20,7 @@ def handled_error_exit(
         ) -> None:
     'Print msg, then exit(1).'
     print(f'ERROR: {msg}')
-    sys.exit(1)
+    sys_exit(1)
 
 
 try:
@@ -138,14 +142,14 @@ class ArgFail(Exception):
 
 
 def parse_args(
-        ) -> argparse.Namespace:
+        ) -> ArgsNamespace:
     'Collect command line arguments.'
     help_epilogue = ('See README.txt for detailed usage instructions, '
                      'command examples, etc.')
-    parser = argparse.ArgumentParser(
+    parser = ArgumentParser(
             description=__doc__,
             epilog=help_epilogue,
-            formatter_class=argparse.RawDescriptionHelpFormatter)
+            formatter_class=RawDescriptionHelpFormatter)
     parser.add_argument('-i',
                         '--input_file',
                         action='append',
@@ -200,7 +204,7 @@ def parse_args(
 
 
 def validate_args_syntax(
-        args: argparse.Namespace
+        args: ArgsNamespace
         ) -> None:
     'Check command args against general syntax expectations.'
 
@@ -315,13 +319,13 @@ def parse_page_range(
 def args_to_pagelist(
         args_input_file: list[str],
         args_page_range: list[str]
-        ) -> tuple[list[pypdf.PageObject], list[io.BufferedReader]]:
+        ) -> tuple[list[pypdf.PageObject], list[BufferedReader]]:
     'Follow args_input_file ranged by args_page_range into pages, open files.'
     pages_to_add = []
     opened_files = []
     new_page_num = 0
     for i, filename in enumerate(args_input_file):
-        if not os.path.isfile(filename):
+        if not isfile(filename):
             raise ArgFail('i', f'{filename} is not a file')
         file = open(filename, 'rb')
         opened_files += [file]
@@ -349,7 +353,7 @@ def args_to_pagelist(
 
 
 def validate_ranges(
-        args: argparse.Namespace,
+        args: ArgsNamespace,
         pages_to_add: list[pypdf.PageObject]
         ) -> None:
     'Check command args\' ranges fit into pages_to_add count.'
@@ -600,7 +604,7 @@ def ornate_nup4(
     'Apply nup4 line guides onto new_page.'
     if args_analyze:
         # borders
-        packet = io.BytesIO()
+        packet = BytesIO()
         c = canvas_class(packet, pagesize=A4)
         c.setLineWidth(0.1)
         c.line(0, A4_HEIGHT, A4_WIDTH, A4_HEIGHT)
@@ -621,7 +625,7 @@ def ornate_nup4(
     x_left_spine_limit = A4_HALF_WIDTH * nup4_geometry.shrink_for_spine
     x_right_spine_limit = A4_WIDTH - x_left_spine_limit
     if args_analyze or is_front_page:
-        packet = io.BytesIO()
+        packet = BytesIO()
         c = canvas_class(packet, pagesize=A4)
     if args_analyze:
         # spine lines