Merge pull request #94 from cs50/customimporter

reorganized imports

Author: Kareem Zidane

src/cs50/flask.py

@@ -1,7 +1,6 @@
 import logging
 
 from distutils.version import StrictVersion
-from os import getenv
 from pkg_resources import get_distribution
 
 from .cs50 import _formatException
@@ -44,6 +43,7 @@ def _execute_after(*args, **kwargs):
 
     # When behind CS50 IDE's proxy, ensure that flask.redirect doesn't redirect from HTTPS to HTTP
     # https://werkzeug.palletsprojects.com/en/0.15.x/middleware/proxy_fix/#module-werkzeug.middleware.proxy_fix
+    from os import getenv
     if getenv("CS50_IDE_TYPE") == "online":
         try:
             import flask

src/cs50/sql.py

@@ -1,17 +1,3 @@
-import datetime
-import decimal
-import importlib
-import logging
-import os
-import re
-import sqlalchemy
-import sqlite3
-import sqlparse
-import sys
-import termcolor
-import warnings
-
-
 class SQL(object):
     """Wrap SQLAlchemy to provide a simple SQL API."""
 
@@ -25,6 +11,13 @@ def __init__(self, url, **kwargs):
         http://docs.sqlalchemy.org/en/latest/dialects/index.html
         """
 
+        # Lazily import
+        import logging
+        import os
+        import re
+        import sqlalchemy
+        import sqlite3
+
         # Get logger
         self._logger = logging.getLogger("cs50")
 
@@ -74,6 +67,13 @@ def connect(dbapi_connection, connection_record):
     def execute(self, sql, *args, **kwargs):
         """Execute a SQL statement."""
 
+        # Lazily import
+        import decimal
+        import sqlalchemy
+        import sqlparse
+        import termcolor
+        import warnings
+
         # Allow only one statement at a time, since SQLite doesn't support multiple
         # https://docs.python.org/3/library/sqlite3.html#sqlite3.Cursor.execute
         statements = sqlparse.parse(sql)
@@ -296,8 +296,15 @@ def _escape(self, value):
         https://docs.sqlalchemy.org/en/latest/core/type_api.html#sqlalchemy.types.TypeEngine.literal_processor
         """
 
+        # Lazily import
+        import sqlparse
+
         def __escape(value):
 
+            # Lazily import
+            import datetime
+            import sqlalchemy
+
             # bool
             if type(value) is bool:
                 return sqlparse.sql.Token(
@@ -366,6 +373,9 @@ def __escape(value):
 def _parse_exception(e):
     """Parses an exception, returns its message."""
 
+    # Lazily import
+    import re
+
     # MySQL
     matches = re.search(r"^\(_mysql_exceptions\.OperationalError\) \(\d+, \"(.+)\"\)$", str(e))
     if matches:
@@ -388,6 +398,10 @@ def _parse_exception(e):
 def _parse_placeholder(token):
     """Infers paramstyle, name from sqlparse.tokens.Name.Placeholder."""
 
+    # Lazily load
+    import re
+    import sqlparse
+
     # Validate token
     if not isinstance(token, sqlparse.sql.Token) or token.ttype != sqlparse.tokens.Name.Placeholder:
         raise TypeError()

tests/python.py

@@ -4,5 +4,5 @@
 
 import cs50
 
-i = cs50.get_int()
-print(i)
+i = cs50.get_int("Input:  ")
+print(f"Output: {i}")